core/num/uint_macros.rs
1macro_rules! uint_impl {
2 (
3 Self = $SelfT:ty,
4 ActualT = $ActualT:ident,
5 SignedT = $SignedT:ident,
6
7 // These are all for use *only* in doc comments.
8 // As such, they're all passed as literals -- passing them as a string
9 // literal is fine if they need to be multiple code tokens.
10 // In non-comments, use the associated constants rather than these.
11 BITS = $BITS:literal,
12 BITS_MINUS_ONE = $BITS_MINUS_ONE:literal,
13 MAX = $MaxV:literal,
14 rot = $rot:literal,
15 rot_op = $rot_op:literal,
16 rot_result = $rot_result:literal,
17 fsh_op = $fsh_op:literal,
18 fshl_result = $fshl_result:literal,
19 fshr_result = $fshr_result:literal,
20 clmul_lhs = $clmul_lhs:literal,
21 clmul_rhs = $clmul_rhs:literal,
22 clmul_result = $clmul_result:literal,
23 swap_op = $swap_op:literal,
24 swapped = $swapped:literal,
25 reversed = $reversed:literal,
26 le_bytes = $le_bytes:literal,
27 be_bytes = $be_bytes:literal,
28 to_xe_bytes_doc = $to_xe_bytes_doc:expr,
29 from_xe_bytes_doc = $from_xe_bytes_doc:expr,
30 bound_condition = $bound_condition:literal,
31 ) => {
32 /// The smallest value that can be represented by this integer type.
33 ///
34 /// # Examples
35 ///
36 /// ```
37 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN, 0);")]
38 /// ```
39 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
40 pub const MIN: Self = 0;
41
42 /// The largest value that can be represented by this integer type
43 #[doc = concat!("(2<sup>", $BITS, "</sup> − 1", $bound_condition, ").")]
44 ///
45 /// # Examples
46 ///
47 /// ```
48 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX, ", stringify!($MaxV), ");")]
49 /// ```
50 #[stable(feature = "assoc_int_consts", since = "1.43.0")]
51 pub const MAX: Self = !0;
52
53 /// The size of this integer type in bits.
54 ///
55 /// # Examples
56 ///
57 /// ```
58 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::BITS, ", stringify!($BITS), ");")]
59 /// ```
60 #[stable(feature = "int_bits_const", since = "1.53.0")]
61 pub const BITS: u32 = Self::MAX.count_ones();
62
63 /// Returns the number of ones in the binary representation of `self`.
64 ///
65 /// # Examples
66 ///
67 /// ```
68 #[doc = concat!("let n = 0b01001100", stringify!($SelfT), ";")]
69 /// assert_eq!(n.count_ones(), 3);
70 ///
71 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
72 #[doc = concat!("assert_eq!(max.count_ones(), ", stringify!($BITS), ");")]
73 ///
74 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
75 /// assert_eq!(zero.count_ones(), 0);
76 /// ```
77 #[stable(feature = "rust1", since = "1.0.0")]
78 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
79 #[doc(alias = "popcount")]
80 #[doc(alias = "popcnt")]
81 #[must_use = "this returns the result of the operation, \
82 without modifying the original"]
83 #[inline(always)]
84 pub const fn count_ones(self) -> u32 {
85 return intrinsics::ctpop(self);
86 }
87
88 /// Returns the number of zeros in the binary representation of `self`.
89 ///
90 /// # Examples
91 ///
92 /// ```
93 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
94 #[doc = concat!("assert_eq!(zero.count_zeros(), ", stringify!($BITS), ");")]
95 ///
96 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
97 /// assert_eq!(max.count_zeros(), 0);
98 /// ```
99 ///
100 /// This is heavily dependent on the width of the type, and thus
101 /// might give surprising results depending on type inference:
102 /// ```
103 /// # fn foo(_: u8) {}
104 /// # fn bar(_: u16) {}
105 /// let lucky = 7;
106 /// foo(lucky);
107 /// assert_eq!(lucky.count_zeros(), 5);
108 /// assert_eq!(lucky.count_ones(), 3);
109 ///
110 /// let lucky = 7;
111 /// bar(lucky);
112 /// assert_eq!(lucky.count_zeros(), 13);
113 /// assert_eq!(lucky.count_ones(), 3);
114 /// ```
115 /// You might want to use [`Self::count_ones`] instead, or emphasize
116 /// the type you're using in the call rather than method syntax:
117 /// ```
118 /// let small = 1;
119 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::count_zeros(small), ", stringify!($BITS_MINUS_ONE) ,");")]
120 /// ```
121 #[stable(feature = "rust1", since = "1.0.0")]
122 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
123 #[must_use = "this returns the result of the operation, \
124 without modifying the original"]
125 #[inline(always)]
126 pub const fn count_zeros(self) -> u32 {
127 (!self).count_ones()
128 }
129
130 /// Returns the number of leading zeros in the binary representation of `self`.
131 ///
132 /// Depending on what you're doing with the value, you might also be interested in the
133 /// [`ilog2`] function which returns a consistent number, even if the type widens.
134 ///
135 /// # Examples
136 ///
137 /// ```
138 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX >> 2;")]
139 /// assert_eq!(n.leading_zeros(), 2);
140 ///
141 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
142 #[doc = concat!("assert_eq!(zero.leading_zeros(), ", stringify!($BITS), ");")]
143 ///
144 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
145 /// assert_eq!(max.leading_zeros(), 0);
146 /// ```
147 #[doc = concat!("[`ilog2`]: ", stringify!($SelfT), "::ilog2")]
148 #[stable(feature = "rust1", since = "1.0.0")]
149 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
150 #[must_use = "this returns the result of the operation, \
151 without modifying the original"]
152 #[inline(always)]
153 pub const fn leading_zeros(self) -> u32 {
154 return intrinsics::ctlz(self as $ActualT);
155 }
156
157 /// Returns the number of trailing zeros in the binary representation
158 /// of `self`.
159 ///
160 /// # Examples
161 ///
162 /// ```
163 #[doc = concat!("let n = 0b0101000", stringify!($SelfT), ";")]
164 /// assert_eq!(n.trailing_zeros(), 3);
165 ///
166 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
167 #[doc = concat!("assert_eq!(zero.trailing_zeros(), ", stringify!($BITS), ");")]
168 ///
169 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
170 #[doc = concat!("assert_eq!(max.trailing_zeros(), 0);")]
171 /// ```
172 #[stable(feature = "rust1", since = "1.0.0")]
173 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
174 #[must_use = "this returns the result of the operation, \
175 without modifying the original"]
176 #[inline(always)]
177 pub const fn trailing_zeros(self) -> u32 {
178 return intrinsics::cttz(self);
179 }
180
181 /// Returns the number of leading ones in the binary representation of `self`.
182 ///
183 /// # Examples
184 ///
185 /// ```
186 #[doc = concat!("let n = !(", stringify!($SelfT), "::MAX >> 2);")]
187 /// assert_eq!(n.leading_ones(), 2);
188 ///
189 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
190 /// assert_eq!(zero.leading_ones(), 0);
191 ///
192 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
193 #[doc = concat!("assert_eq!(max.leading_ones(), ", stringify!($BITS), ");")]
194 /// ```
195 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
196 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
197 #[must_use = "this returns the result of the operation, \
198 without modifying the original"]
199 #[inline(always)]
200 pub const fn leading_ones(self) -> u32 {
201 (!self).leading_zeros()
202 }
203
204 /// Returns the number of trailing ones in the binary representation
205 /// of `self`.
206 ///
207 /// # Examples
208 ///
209 /// ```
210 #[doc = concat!("let n = 0b1010111", stringify!($SelfT), ";")]
211 /// assert_eq!(n.trailing_ones(), 3);
212 ///
213 #[doc = concat!("let zero = 0", stringify!($SelfT), ";")]
214 /// assert_eq!(zero.trailing_ones(), 0);
215 ///
216 #[doc = concat!("let max = ", stringify!($SelfT),"::MAX;")]
217 #[doc = concat!("assert_eq!(max.trailing_ones(), ", stringify!($BITS), ");")]
218 /// ```
219 #[stable(feature = "leading_trailing_ones", since = "1.46.0")]
220 #[rustc_const_stable(feature = "leading_trailing_ones", since = "1.46.0")]
221 #[must_use = "this returns the result of the operation, \
222 without modifying the original"]
223 #[inline(always)]
224 pub const fn trailing_ones(self) -> u32 {
225 (!self).trailing_zeros()
226 }
227
228 /// Returns the minimum number of bits required to represent `self`.
229 ///
230 /// This method returns zero if `self` is zero.
231 ///
232 /// # Examples
233 ///
234 /// ```
235 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".bit_width(), 0);")]
236 #[doc = concat!("assert_eq!(0b111_", stringify!($SelfT), ".bit_width(), 3);")]
237 #[doc = concat!("assert_eq!(0b1110_", stringify!($SelfT), ".bit_width(), 4);")]
238 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.bit_width(), ", stringify!($BITS), ");")]
239 /// ```
240 #[stable(feature = "uint_bit_width", since = "1.97.0")]
241 #[rustc_const_stable(feature = "uint_bit_width", since = "1.97.0")]
242 #[must_use = "this returns the result of the operation, \
243 without modifying the original"]
244 #[inline(always)]
245 pub const fn bit_width(self) -> u32 {
246 Self::BITS - self.leading_zeros()
247 }
248
249 /// Returns `self` with only the most significant bit set, or `0` if
250 /// the input is `0`.
251 ///
252 /// # Examples
253 ///
254 /// ```
255 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
256 ///
257 /// assert_eq!(n.isolate_highest_one(), 0b_01000000);
258 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_highest_one(), 0);")]
259 /// ```
260 #[stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
261 #[rustc_const_stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
262 #[must_use = "this returns the result of the operation, \
263 without modifying the original"]
264 #[inline(always)]
265 pub const fn isolate_highest_one(self) -> Self {
266 self & (((1 as $SelfT) << (<$SelfT>::BITS - 1)).wrapping_shr(self.leading_zeros()))
267 }
268
269 /// Returns `self` with only the least significant bit set, or `0` if
270 /// the input is `0`.
271 ///
272 /// # Examples
273 ///
274 /// ```
275 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b_01100100;")]
276 ///
277 /// assert_eq!(n.isolate_lowest_one(), 0b_00000100);
278 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".isolate_lowest_one(), 0);")]
279 /// ```
280 #[stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
281 #[rustc_const_stable(feature = "isolate_most_least_significant_one", since = "1.97.0")]
282 #[must_use = "this returns the result of the operation, \
283 without modifying the original"]
284 #[inline(always)]
285 pub const fn isolate_lowest_one(self) -> Self {
286 self & self.wrapping_neg()
287 }
288
289 /// Returns the index of the highest bit set to one in `self`, or `None`
290 /// if `self` is `0`.
291 ///
292 /// Note that this is equivalent to [`checked_ilog2`](Self::checked_ilog2).
293 ///
294 /// # Examples
295 ///
296 /// ```
297 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".highest_one(), None);")]
298 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".highest_one(), Some(0));")]
299 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".highest_one(), Some(4));")]
300 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".highest_one(), Some(4));")]
301 /// ```
302 #[stable(feature = "int_lowest_highest_one", since = "1.97.0")]
303 #[rustc_const_stable(feature = "int_lowest_highest_one", since = "1.97.0")]
304 #[must_use = "this returns the result of the operation, \
305 without modifying the original"]
306 #[inline(always)]
307 pub const fn highest_one(self) -> Option<u32> {
308 match NonZero::new(self) {
309 Some(v) => Some(v.highest_one()),
310 None => None,
311 }
312 }
313
314 /// Returns the index of the lowest bit set to one in `self`, or `None`
315 /// if `self` is `0`.
316 ///
317 /// # Examples
318 ///
319 /// ```
320 #[doc = concat!("assert_eq!(0b0_", stringify!($SelfT), ".lowest_one(), None);")]
321 #[doc = concat!("assert_eq!(0b1_", stringify!($SelfT), ".lowest_one(), Some(0));")]
322 #[doc = concat!("assert_eq!(0b1_0000_", stringify!($SelfT), ".lowest_one(), Some(4));")]
323 #[doc = concat!("assert_eq!(0b1_1111_", stringify!($SelfT), ".lowest_one(), Some(0));")]
324 /// ```
325 #[stable(feature = "int_lowest_highest_one", since = "1.97.0")]
326 #[rustc_const_stable(feature = "int_lowest_highest_one", since = "1.97.0")]
327 #[must_use = "this returns the result of the operation, \
328 without modifying the original"]
329 #[inline(always)]
330 pub const fn lowest_one(self) -> Option<u32> {
331 match NonZero::new(self) {
332 Some(v) => Some(v.lowest_one()),
333 None => None,
334 }
335 }
336
337 /// Returns the bit pattern of `self` reinterpreted as a signed integer of the same size.
338 ///
339 /// This produces the same result as an `as` cast, but ensures that the bit-width remains
340 /// the same.
341 ///
342 /// # Examples
343 ///
344 /// ```
345 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
346 ///
347 #[doc = concat!("assert_eq!(n.cast_signed(), -1", stringify!($SignedT), ");")]
348 /// ```
349 #[stable(feature = "integer_sign_cast", since = "1.87.0")]
350 #[rustc_const_stable(feature = "integer_sign_cast", since = "1.87.0")]
351 #[must_use = "this returns the result of the operation, \
352 without modifying the original"]
353 #[inline(always)]
354 pub const fn cast_signed(self) -> $SignedT {
355 self as $SignedT
356 }
357
358 /// Saturating conversion of `self` to a signed integer of the same size.
359 ///
360 /// The signed integer's maximum value is returned if `self` is larger
361 /// than the maximum positive value representable by the signed integer.
362 ///
363 /// For other kinds of signed integer casts, see
364 /// [`cast_signed`](Self::cast_signed),
365 /// [`checked_cast_signed`](Self::checked_cast_signed),
366 /// or [`strict_cast_signed`](Self::strict_cast_signed).
367 ///
368 /// # Examples
369 ///
370 /// ```
371 /// #![feature(integer_cast_extras)]
372 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
373 ///
374 #[doc = concat!("assert_eq!(n.saturating_cast_signed(), ", stringify!($SignedT), "::MAX);")]
375 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".saturating_cast_signed(), 64", stringify!($SignedT), ");")]
376 /// ```
377 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
378 #[unstable(feature = "integer_cast_extras", issue = "154650")]
379 #[must_use = "this returns the result of the operation, \
380 without modifying the original"]
381 #[inline(always)]
382 pub const fn saturating_cast_signed(self) -> $SignedT {
383 // Clamp to the signed integer max size, which is ActualT::MAX >> 1.
384 if self <= <$SignedT>::MAX.cast_unsigned() {
385 self.cast_signed()
386 } else {
387 <$SignedT>::MAX
388 }
389 }
390
391 /// Checked conversion of `self` to a signed integer of the same size,
392 /// returning `None` if `self` is larger than the signed integer's
393 /// maximum value.
394 ///
395 /// For other kinds of signed integer casts, see
396 /// [`cast_signed`](Self::cast_signed),
397 /// [`saturating_cast_signed`](Self::saturating_cast_signed),
398 /// or [`strict_cast_signed`](Self::strict_cast_signed).
399 ///
400 /// # Examples
401 ///
402 /// ```
403 /// #![feature(integer_cast_extras)]
404 #[doc = concat!("let n = ", stringify!($SelfT), "::MAX;")]
405 ///
406 #[doc = concat!("assert_eq!(n.checked_cast_signed(), None);")]
407 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_cast_signed(), Some(64", stringify!($SignedT), "));")]
408 /// ```
409 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
410 #[unstable(feature = "integer_cast_extras", issue = "154650")]
411 #[must_use = "this returns the result of the operation, \
412 without modifying the original"]
413 #[inline(always)]
414 pub const fn checked_cast_signed(self) -> Option<$SignedT> {
415 if self <= <$SignedT>::MAX.cast_unsigned() {
416 Some(self.cast_signed())
417 } else {
418 None
419 }
420 }
421
422 /// Strict conversion of `self` to a signed integer of the same size,
423 /// which panics if `self` is larger than the signed integer's maximum
424 /// value.
425 ///
426 /// For other kinds of signed integer casts, see
427 /// [`cast_signed`](Self::cast_signed),
428 /// [`checked_cast_signed`](Self::checked_cast_signed),
429 /// or [`saturating_cast_signed`](Self::saturating_cast_signed).
430 ///
431 /// # Examples
432 ///
433 /// ```should_panic
434 /// #![feature(integer_cast_extras)]
435 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_cast_signed();")]
436 /// ```
437 #[rustc_const_unstable(feature = "integer_cast_extras", issue = "154650")]
438 #[unstable(feature = "integer_cast_extras", issue = "154650")]
439 #[must_use = "this returns the result of the operation, \
440 without modifying the original"]
441 #[inline]
442 #[track_caller]
443 pub const fn strict_cast_signed(self) -> $SignedT {
444 match self.checked_cast_signed() {
445 Some(n) => n,
446 None => imp::overflow_panic::cast_integer(),
447 }
448 }
449
450 /// Shifts the bits to the left by a specified amount, `n`,
451 /// wrapping the truncated bits to the end of the resulting integer.
452 ///
453 /// `rotate_left(n)` is equivalent to applying `rotate_left(1)` a total of `n` times. In
454 /// particular, a rotation by the number of bits in `self` returns the input value
455 /// unchanged.
456 ///
457 /// Please note this isn't the same operation as the `<<` shifting operator!
458 ///
459 /// # Examples
460 ///
461 /// ```
462 #[doc = concat!("let n = ", $rot_op, stringify!($SelfT), ";")]
463 #[doc = concat!("let m = ", $rot_result, ";")]
464 ///
465 #[doc = concat!("assert_eq!(n.rotate_left(", $rot, "), m);")]
466 #[doc = concat!("assert_eq!(n.rotate_left(1024), n);")]
467 /// ```
468 #[stable(feature = "rust1", since = "1.0.0")]
469 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
470 #[must_use = "this returns the result of the operation, \
471 without modifying the original"]
472 #[inline(always)]
473 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
474 pub const fn rotate_left(self, n: u32) -> Self {
475 return intrinsics::rotate_left(self, n);
476 }
477
478 /// Shifts the bits to the right by a specified amount, `n`,
479 /// wrapping the truncated bits to the beginning of the resulting
480 /// integer.
481 ///
482 /// `rotate_right(n)` is equivalent to applying `rotate_right(1)` a total of `n` times. In
483 /// particular, a rotation by the number of bits in `self` returns the input value
484 /// unchanged.
485 ///
486 /// Please note this isn't the same operation as the `>>` shifting operator!
487 ///
488 /// # Examples
489 ///
490 /// ```
491 #[doc = concat!("let n = ", $rot_result, stringify!($SelfT), ";")]
492 #[doc = concat!("let m = ", $rot_op, ";")]
493 ///
494 #[doc = concat!("assert_eq!(n.rotate_right(", $rot, "), m);")]
495 #[doc = concat!("assert_eq!(n.rotate_right(1024), n);")]
496 /// ```
497 #[stable(feature = "rust1", since = "1.0.0")]
498 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
499 #[must_use = "this returns the result of the operation, \
500 without modifying the original"]
501 #[inline(always)]
502 #[rustc_allow_const_fn_unstable(const_trait_impl)] // for the intrinsic fallback
503 pub const fn rotate_right(self, n: u32) -> Self {
504 return intrinsics::rotate_right(self, n);
505 }
506
507 /// Performs a left funnel shift.
508 ///
509 /// This operation can be thought of as concatenating `self` and `right` into an
510 /// integer twice the size of
511 #[doc = concat!("`", stringify!($SelfT) , "`,")]
512 /// performing a left shift by `n`, and returning the **left half** of the result.
513 ///
514 /// The name comes from "funneling" a wider integer to a narrower integer.
515 ///
516 /// # Panics
517 ///
518 /// ## Overflow behavior
519 ///
520 /// If overflow checks are enabled (default in debug mode), this function will panic if `n`
521 /// is greater than or equal to the number of bits in `self`. If overflow checks are
522 /// disabled (default in release mode), there is no panic; instead, the value is shifted
523 /// by `n % Self::BITS`.
524 // FIXME(wrapping_funnel_shifts): link to `wrapping_funnel_shl` when stable.
525 ///
526 /// # Examples
527 ///
528 /// ```
529 #[doc = concat!("let a = ", $rot_op, "_", stringify!($SelfT), ";")]
530 #[doc = concat!("let b = ", $fsh_op, "_", stringify!($SelfT), ";")]
531 ///
532 #[doc = concat!("assert_eq!(a.funnel_shl(b, ", $rot, "), ", $fshl_result, ");")]
533 ///
534 /// // Using zeros as the right operand acts as a normal shift left
535 #[doc = concat!("assert_eq!(a.funnel_shl(0, ", $rot, "), a << ", $rot, ");")]
536 ///
537 /// // Shifting by 0 returns `self` unchanged
538 #[doc = concat!("assert_eq!(a.funnel_shl(b, 0), a);")]
539 ///
540 /// // Using the same value as the right operand acts as a rotate
541 #[doc = concat!("assert_eq!(a.funnel_shl(a, ", $rot, "), a.rotate_left(", $rot, "));")]
542 /// ```
543 ///
544 /// Note that while `funnel_shl` can act as a rotate, it does not allow for
545 /// rotating by an unbounded amount like [`rotate_left`](Self::rotate_left) does:
546 ///
547 /// ```should_panic
548 /// # #![feature(cfg_overflow_checks)]
549 /// # #[cfg(overflow_checks)] {
550 #[doc = concat!("let a = ", stringify!($SelfT), "::MAX;")]
551 /// // Okay
552 #[doc = concat!("let _ = a.rotate_left(", stringify!($SelfT), "::BITS);")]
553 /// // Panics (only when overflow checks are enabled)
554 #[doc = concat!("let _ = a.funnel_shl(a, ", stringify!($SelfT), "::BITS);")]
555 /// # }
556 /// # #[cfg(not(overflow_checks))] panic!("fulfill should_panic");
557 /// ```
558 #[rustc_const_stable(feature = "funnel_shifts", since = "CURRENT_RUSTC_VERSION")]
559 #[stable(feature = "funnel_shifts", since = "CURRENT_RUSTC_VERSION")]
560 #[must_use = "this returns the result of the operation, without modifying the original"]
561 #[inline(always)]
562 #[rustc_inherit_overflow_checks]
563 pub const fn funnel_shl(self, right: Self, n: u32) -> Self {
564 if intrinsics::overflow_checks() {
565 assert!(n < Self::BITS, "attempt to funnel shift left with overflow");
566 }
567 // SAFETY: `n` is wrapped to within range
568 unsafe {
569 let n = n & (Self::BITS - 1);
570 self.unchecked_funnel_shl(right, n)
571 }
572 }
573
574 /// Performs a right funnel shift.
575 ///
576 /// This operation can be thought of as concatenating `self` and `right` into an
577 /// integer twice the size of
578 #[doc = concat!("`", stringify!($SelfT) , "`,")]
579 /// performing a right shift by `n`, and returning the **right half** of the result.
580 ///
581 /// The name comes from "funneling" a wider integer to a narrower integer.
582 ///
583 /// # Panics
584 ///
585 /// ## Overflow behavior
586 ///
587 /// If overflow checks are enabled (default in debug mode), this function will panic if `n`
588 /// is greater than or equal to the number of bits in `self`. If overflow checks are
589 /// disabled (default in release mode), there is no panic; instead, the value is shifted
590 /// by `n % Self::BITS`.
591 // FIXME(wrapping_funnel_shifts): link to `wrapping_funnel_shr` when stable.
592 ///
593 /// # Examples
594 ///
595 /// ```
596 #[doc = concat!("let a = ", $rot_op, "_", stringify!($SelfT), ";")]
597 #[doc = concat!("let b = ", $fsh_op, "_", stringify!($SelfT), ";")]
598 ///
599 #[doc = concat!("assert_eq!(a.funnel_shr(b, ", $rot, "), ", $fshr_result, ");")]
600 ///
601 /// // Using zeros as the left operand acts as a normal shift right
602 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".funnel_shr(a, ", $rot, "), a >> ", $rot, ");")]
603 ///
604 /// // Shifting by 0 returns `right` unchanged
605 #[doc = concat!("assert_eq!(b.funnel_shr(a, 0), a);")]
606 ///
607 /// // Using the same value as the right operand acts as a rotate
608 #[doc = concat!("assert_eq!(a.funnel_shr(a, ", $rot, "), a.rotate_right(", $rot, "));")]
609 /// ```
610 ///
611 /// Note that while `funnel_shr` can act as a rotate, it does not allow for
612 /// rotating by an unbounded amount like [`rotate_right`](Self::rotate_right) does:
613 ///
614 /// ```should_panic
615 /// # #![feature(cfg_overflow_checks)]
616 /// # #[cfg(overflow_checks)] {
617 #[doc = concat!("let a = ", stringify!($SelfT), "::MAX;")]
618 /// // Okay
619 #[doc = concat!("let _ = a.rotate_right(", stringify!($SelfT), "::BITS);")]
620 /// // Panics (only when overflow checks are enabled)
621 #[doc = concat!("let _ = a.funnel_shr(a, ", stringify!($SelfT), "::BITS);")]
622 /// # }
623 /// # #[cfg(not(overflow_checks))] panic!("fulfill should_panic");
624 /// ```
625 #[rustc_const_stable(feature = "funnel_shifts", since = "CURRENT_RUSTC_VERSION")]
626 #[stable(feature = "funnel_shifts", since = "CURRENT_RUSTC_VERSION")]
627 #[must_use = "this returns the result of the operation, without modifying the original"]
628 #[inline(always)]
629 #[rustc_inherit_overflow_checks]
630 pub const fn funnel_shr(self, right: Self, n: u32) -> Self {
631 if intrinsics::overflow_checks() {
632 assert!(n < Self::BITS, "attempt to funnel shift right with overflow");
633 }
634 // SAFETY: `n` is wrapped to within range
635 unsafe {
636 let n = n & (Self::BITS - 1);
637 self.unchecked_funnel_shr(right, n)
638 }
639 }
640
641 /// Unchecked funnel shift left.
642 ///
643 /// # Safety
644 ///
645 /// This results in undefined behavior if `n` is greater than or equal to
646 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
647 /// i.e. when [`funnel_shl`](Self::funnel_shl) would panic.
648 ///
649 #[rustc_const_stable(feature = "funnel_shifts", since = "CURRENT_RUSTC_VERSION")]
650 #[stable(feature = "funnel_shifts", since = "CURRENT_RUSTC_VERSION")]
651 #[rustc_allow_const_fn_unstable(const_trait_impl)]
652 #[must_use = "this returns the result of the operation, without modifying the original"]
653 #[inline(always)]
654 #[track_caller]
655 pub const unsafe fn unchecked_funnel_shl(self, right: Self, n: u32) -> Self {
656 assert_unsafe_precondition!(
657 check_language_ub,
658 concat!(stringify!($SelfT), "::unchecked_funnel_shl cannot overflow"),
659 (n: u32 = n) => n < <$ActualT>::BITS,
660 );
661
662 // SAFETY: this is guaranteed to be safe by the caller.
663 unsafe {
664 intrinsics::unchecked_funnel_shl(self, right, n)
665 }
666 }
667
668 /// Unchecked funnel shift right.
669 ///
670 /// # Safety
671 ///
672 /// This results in undefined behavior if `n` is greater than or equal to
673 #[doc = concat!("`", stringify!($SelfT) , "::BITS`,")]
674 /// i.e. when [`funnel_shr`](Self::funnel_shr) would panic.
675 ///
676 #[rustc_const_stable(feature = "funnel_shifts", since = "CURRENT_RUSTC_VERSION")]
677 #[stable(feature = "funnel_shifts", since = "CURRENT_RUSTC_VERSION")]
678 #[rustc_allow_const_fn_unstable(const_trait_impl)]
679 #[must_use = "this returns the result of the operation, without modifying the original"]
680 #[inline(always)]
681 #[track_caller]
682 pub const unsafe fn unchecked_funnel_shr(self, right: Self, n: u32) -> Self {
683 assert_unsafe_precondition!(
684 check_language_ub,
685 concat!(stringify!($SelfT), "::unchecked_funnel_shr cannot overflow"),
686 (n: u32 = n) => n < <$ActualT>::BITS,
687 );
688
689 // SAFETY: this is guaranteed to be safe by the caller.
690 unsafe {
691 intrinsics::unchecked_funnel_shr(self, right, n)
692 }
693 }
694
695 /// Performs a carry-less multiplication, returning the lower bits.
696 ///
697 /// This operation is similar to long multiplication in base 2, except that exclusive or is
698 /// used instead of addition. The implementation is equivalent to:
699 ///
700 /// ```no_run
701 #[doc = concat!("pub fn carryless_mul(lhs: ", stringify!($SelfT), ", rhs: ", stringify!($SelfT), ") -> ", stringify!($SelfT), "{")]
702 /// let mut retval = 0;
703 #[doc = concat!(" for i in 0..", stringify!($SelfT), "::BITS {")]
704 /// if (rhs >> i) & 1 != 0 {
705 /// // long multiplication would use +=
706 /// retval ^= lhs << i;
707 /// }
708 /// }
709 /// retval
710 /// }
711 /// ```
712 ///
713 /// The actual implementation is more efficient, and on some platforms lowers directly to a
714 /// dedicated instruction.
715 ///
716 /// # Uses
717 ///
718 /// Carryless multiplication can be used to turn a bitmask of quote characters into a
719 /// bit mask of characters surrounded by quotes:
720 ///
721 /// ```no_run
722 /// r#"abc xxx "foobar" zzz "a"!"#; // input string
723 /// 0b0000000010000001000001010; // quote_mask
724 /// 0b0000000001111110000000100; // quote_mask.carryless_mul(!0) & !quote_mask
725 /// ```
726 ///
727 /// Another use is in cryptography, where carryless multiplication allows for efficient
728 /// implementations of polynomial multiplication in `GF(2)[X]`, the polynomial ring
729 /// over `GF(2)`.
730 ///
731 /// # Examples
732 ///
733 /// ```
734 /// #![feature(uint_carryless_mul)]
735 ///
736 #[doc = concat!("let a = ", $clmul_lhs, stringify!($SelfT), ";")]
737 #[doc = concat!("let b = ", $clmul_rhs, stringify!($SelfT), ";")]
738 ///
739 #[doc = concat!("assert_eq!(a.carryless_mul(b), ", $clmul_result, ");")]
740 /// ```
741 #[rustc_const_unstable(feature = "uint_carryless_mul", issue = "152080")]
742 #[doc(alias = "clmul")]
743 #[unstable(feature = "uint_carryless_mul", issue = "152080")]
744 #[must_use = "this returns the result of the operation, \
745 without modifying the original"]
746 #[inline(always)]
747 pub const fn carryless_mul(self, rhs: Self) -> Self {
748 intrinsics::carryless_mul(self, rhs)
749 }
750
751 /// Reverses the byte order of the integer.
752 ///
753 /// # Examples
754 ///
755 /// ```
756 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
757 /// let m = n.swap_bytes();
758 ///
759 #[doc = concat!("assert_eq!(m, ", $swapped, ");")]
760 /// ```
761 #[stable(feature = "rust1", since = "1.0.0")]
762 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
763 #[must_use = "this returns the result of the operation, \
764 without modifying the original"]
765 #[inline(always)]
766 pub const fn swap_bytes(self) -> Self {
767 intrinsics::bswap(self as $ActualT) as Self
768 }
769
770 /// Returns an integer with the bit locations specified by `mask` packed
771 /// contiguously into the least significant bits of the result.
772 /// ```
773 /// #![feature(uint_gather_scatter_bits)]
774 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1011_1100;")]
775 ///
776 /// assert_eq!(n.extract_bits(0b0010_0100), 0b0000_0011);
777 /// assert_eq!(n.extract_bits(0xF0), 0b0000_1011);
778 /// ```
779 #[doc(alias = "pext")]
780 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
781 #[must_use = "this returns the result of the operation, \
782 without modifying the original"]
783 #[inline]
784 pub const fn extract_bits(self, mask: Self) -> Self {
785 imp::int_bits::$ActualT::extract_impl(self as $ActualT, mask as $ActualT) as $SelfT
786 }
787
788 /// Returns an integer with the least significant bits of `self`
789 /// distributed to the bit locations specified by `mask`.
790 /// ```
791 /// #![feature(uint_gather_scatter_bits)]
792 #[doc = concat!("let n: ", stringify!($SelfT), " = 0b1010_1101;")]
793 ///
794 /// assert_eq!(n.deposit_bits(0b0101_0101), 0b0101_0001);
795 /// assert_eq!(n.deposit_bits(0xF0), 0b1101_0000);
796 /// ```
797 #[doc(alias = "pdep")]
798 #[unstable(feature = "uint_gather_scatter_bits", issue = "149069")]
799 #[must_use = "this returns the result of the operation, \
800 without modifying the original"]
801 #[inline]
802 pub const fn deposit_bits(self, mask: Self) -> Self {
803 imp::int_bits::$ActualT::deposit_impl(self as $ActualT, mask as $ActualT) as $SelfT
804 }
805
806 /// Reverses the order of bits in the integer. The least significant bit becomes the most significant bit,
807 /// second least-significant bit becomes second most-significant bit, etc.
808 ///
809 /// # Examples
810 ///
811 /// ```
812 #[doc = concat!("let n = ", $swap_op, stringify!($SelfT), ";")]
813 /// let m = n.reverse_bits();
814 ///
815 #[doc = concat!("assert_eq!(m, ", $reversed, ");")]
816 #[doc = concat!("assert_eq!(0, 0", stringify!($SelfT), ".reverse_bits());")]
817 /// ```
818 #[stable(feature = "reverse_bits", since = "1.37.0")]
819 #[rustc_const_stable(feature = "reverse_bits", since = "1.37.0")]
820 #[must_use = "this returns the result of the operation, \
821 without modifying the original"]
822 #[inline(always)]
823 pub const fn reverse_bits(self) -> Self {
824 intrinsics::bitreverse(self as $ActualT) as Self
825 }
826
827 /// Converts an integer from big endian to the target's endianness.
828 ///
829 /// On big endian this is a no-op. On little endian the bytes are
830 /// swapped.
831 ///
832 /// # Examples
833 ///
834 /// ```
835 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
836 ///
837 /// if cfg!(target_endian = "big") {
838 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n)")]
839 /// } else {
840 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_be(n), n.swap_bytes())")]
841 /// }
842 /// ```
843 #[stable(feature = "rust1", since = "1.0.0")]
844 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
845 #[must_use]
846 #[inline(always)]
847 pub const fn from_be(x: Self) -> Self {
848 cfg_select! {
849 target_endian = "big" => x,
850 _ => x.swap_bytes(),
851 }
852 }
853
854 /// Converts an integer from little endian to the target's endianness.
855 ///
856 /// On little endian this is a no-op. On big endian the bytes are
857 /// swapped.
858 ///
859 /// # Examples
860 ///
861 /// ```
862 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
863 ///
864 /// if cfg!(target_endian = "little") {
865 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n)")]
866 /// } else {
867 #[doc = concat!(" assert_eq!(", stringify!($SelfT), "::from_le(n), n.swap_bytes())")]
868 /// }
869 /// ```
870 #[stable(feature = "rust1", since = "1.0.0")]
871 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
872 #[must_use]
873 #[inline(always)]
874 pub const fn from_le(x: Self) -> Self {
875 cfg_select! {
876 target_endian = "little" => x,
877 _ => x.swap_bytes(),
878 }
879 }
880
881 /// Converts `self` to big endian from the target's endianness.
882 ///
883 /// On big endian this is a no-op. On little endian the bytes are
884 /// swapped.
885 ///
886 /// # Examples
887 ///
888 /// ```
889 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
890 ///
891 /// if cfg!(target_endian = "big") {
892 /// assert_eq!(n.to_be(), n)
893 /// } else {
894 /// assert_eq!(n.to_be(), n.swap_bytes())
895 /// }
896 /// ```
897 #[stable(feature = "rust1", since = "1.0.0")]
898 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
899 #[must_use = "this returns the result of the operation, \
900 without modifying the original"]
901 #[inline(always)]
902 pub const fn to_be(self) -> Self { // or not to be?
903 cfg_select! {
904 target_endian = "big" => self,
905 _ => self.swap_bytes(),
906 }
907 }
908
909 /// Converts `self` to little endian from the target's endianness.
910 ///
911 /// On little endian this is a no-op. On big endian the bytes are
912 /// swapped.
913 ///
914 /// # Examples
915 ///
916 /// ```
917 #[doc = concat!("let n = 0x1A", stringify!($SelfT), ";")]
918 ///
919 /// if cfg!(target_endian = "little") {
920 /// assert_eq!(n.to_le(), n)
921 /// } else {
922 /// assert_eq!(n.to_le(), n.swap_bytes())
923 /// }
924 /// ```
925 #[stable(feature = "rust1", since = "1.0.0")]
926 #[rustc_const_stable(feature = "const_math", since = "1.32.0")]
927 #[must_use = "this returns the result of the operation, \
928 without modifying the original"]
929 #[inline(always)]
930 pub const fn to_le(self) -> Self {
931 cfg_select! {
932 target_endian = "little" => self,
933 _ => self.swap_bytes(),
934 }
935 }
936
937 /// Checked integer addition. Computes `self + rhs`, returning `None`
938 /// if overflow occurred.
939 ///
940 /// # Examples
941 ///
942 /// ```
943 #[doc = concat!(
944 "assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(1), ",
945 "Some(", stringify!($SelfT), "::MAX - 1));"
946 )]
947 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add(3), None);")]
948 /// ```
949 #[stable(feature = "rust1", since = "1.0.0")]
950 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
951 #[must_use = "this returns the result of the operation, \
952 without modifying the original"]
953 #[inline]
954 pub const fn checked_add(self, rhs: Self) -> Option<Self> {
955 // This used to use `overflowing_add`, but that means it ends up being
956 // a `wrapping_add`, losing some optimization opportunities. Notably,
957 // phrasing it this way helps `.checked_add(1)` optimize to a check
958 // against `MAX` and a `add nuw`.
959 // Per <https://github.com/rust-lang/rust/pull/124114#issuecomment-2066173305>,
960 // LLVM is happy to re-form the intrinsic later if useful.
961
962 if intrinsics::unlikely(intrinsics::add_with_overflow(self, rhs).1) {
963 None
964 } else {
965 // SAFETY: Just checked it doesn't overflow
966 Some(unsafe { intrinsics::unchecked_add(self, rhs) })
967 }
968 }
969
970 /// Strict integer addition. Computes `self + rhs`, panicking
971 /// if overflow occurred.
972 ///
973 /// # Panics
974 ///
975 /// ## Overflow behavior
976 ///
977 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
978 ///
979 /// # Examples
980 ///
981 /// ```
982 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).strict_add(1), ", stringify!($SelfT), "::MAX - 1);")]
983 /// ```
984 ///
985 /// The following panics because of overflow:
986 ///
987 /// ```should_panic
988 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add(3);")]
989 /// ```
990 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
991 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
992 #[must_use = "this returns the result of the operation, \
993 without modifying the original"]
994 #[inline]
995 #[track_caller]
996 pub const fn strict_add(self, rhs: Self) -> Self {
997 let (a, b) = self.overflowing_add(rhs);
998 if b { imp::overflow_panic::add() } else { a }
999 }
1000
1001 /// Unchecked integer addition. Computes `self + rhs`, assuming overflow
1002 /// cannot occur.
1003 ///
1004 /// Calling `x.unchecked_add(y)` is semantically equivalent to calling
1005 /// `x.`[`checked_add`]`(y).`[`unwrap_unchecked`]`()`.
1006 ///
1007 /// If you're just trying to avoid the panic in debug mode, then **do not**
1008 /// use this. Instead, you're looking for [`wrapping_add`].
1009 ///
1010 /// # Safety
1011 ///
1012 /// This results in undefined behavior when overflow occurs, i.e. when
1013 /// [`checked_add`] would return `None`.
1014 ///
1015 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1016 #[doc = concat!("[`checked_add`]: ", stringify!($SelfT), "::checked_add")]
1017 #[doc = concat!("[`wrapping_add`]: ", stringify!($SelfT), "::wrapping_add")]
1018 #[stable(feature = "unchecked_math", since = "1.79.0")]
1019 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1020 #[must_use = "this returns the result of the operation, \
1021 without modifying the original"]
1022 #[inline(always)]
1023 #[track_caller]
1024 pub const unsafe fn unchecked_add(self, rhs: Self) -> Self {
1025 assert_unsafe_precondition!(
1026 check_language_ub,
1027 concat!(stringify!($SelfT), "::unchecked_add cannot overflow"),
1028 (
1029 lhs: $SelfT = self,
1030 rhs: $SelfT = rhs,
1031 ) => !lhs.overflowing_add(rhs).1,
1032 );
1033
1034 // SAFETY: this is guaranteed to be safe by the caller.
1035 unsafe {
1036 intrinsics::unchecked_add(self, rhs)
1037 }
1038 }
1039
1040 /// Checked addition with a signed integer. Computes `self + rhs`,
1041 /// returning `None` if overflow occurred.
1042 ///
1043 /// # Examples
1044 ///
1045 /// ```
1046 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(2), Some(3));")]
1047 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_add_signed(-2), None);")]
1048 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_add_signed(3), None);")]
1049 /// ```
1050 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
1051 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
1052 #[must_use = "this returns the result of the operation, \
1053 without modifying the original"]
1054 #[inline]
1055 pub const fn checked_add_signed(self, rhs: $SignedT) -> Option<Self> {
1056 let (a, b) = self.overflowing_add_signed(rhs);
1057 if intrinsics::unlikely(b) { None } else { Some(a) }
1058 }
1059
1060 /// Strict addition with a signed integer. Computes `self + rhs`,
1061 /// panicking if overflow occurred.
1062 ///
1063 /// # Panics
1064 ///
1065 /// ## Overflow behavior
1066 ///
1067 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1068 ///
1069 /// # Examples
1070 ///
1071 /// ```
1072 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_add_signed(2), 3);")]
1073 /// ```
1074 ///
1075 /// The following panic because of overflow:
1076 ///
1077 /// ```should_panic
1078 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_add_signed(-2);")]
1079 /// ```
1080 ///
1081 /// ```should_panic
1082 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX - 2).strict_add_signed(3);")]
1083 /// ```
1084 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1085 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1086 #[must_use = "this returns the result of the operation, \
1087 without modifying the original"]
1088 #[inline]
1089 #[track_caller]
1090 pub const fn strict_add_signed(self, rhs: $SignedT) -> Self {
1091 let (a, b) = self.overflowing_add_signed(rhs);
1092 if b { imp::overflow_panic::add() } else { a }
1093 }
1094
1095 /// Checked integer subtraction. Computes `self - rhs`, returning
1096 /// `None` if overflow occurred.
1097 ///
1098 /// # Examples
1099 ///
1100 /// ```
1101 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub(1), Some(0));")]
1102 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_sub(1), None);")]
1103 /// ```
1104 #[stable(feature = "rust1", since = "1.0.0")]
1105 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1106 #[must_use = "this returns the result of the operation, \
1107 without modifying the original"]
1108 #[inline]
1109 pub const fn checked_sub(self, rhs: Self) -> Option<Self> {
1110 // Per PR#103299, there's no advantage to the `overflowing` intrinsic
1111 // for *unsigned* subtraction and we just emit the manual check anyway.
1112 // Thus, rather than using `overflowing_sub` that produces a wrapping
1113 // subtraction, check it ourself so we can use an unchecked one.
1114
1115 if self < rhs {
1116 None
1117 } else {
1118 // SAFETY: just checked this can't overflow
1119 Some(unsafe { intrinsics::unchecked_sub(self, rhs) })
1120 }
1121 }
1122
1123 /// Strict integer subtraction. Computes `self - rhs`, panicking if
1124 /// overflow occurred.
1125 ///
1126 /// # Panics
1127 ///
1128 /// ## Overflow behavior
1129 ///
1130 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1131 ///
1132 /// # Examples
1133 ///
1134 /// ```
1135 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".strict_sub(1), 0);")]
1136 /// ```
1137 ///
1138 /// The following panics because of overflow:
1139 ///
1140 /// ```should_panic
1141 #[doc = concat!("let _ = 0", stringify!($SelfT), ".strict_sub(1);")]
1142 /// ```
1143 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1144 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1145 #[must_use = "this returns the result of the operation, \
1146 without modifying the original"]
1147 #[inline]
1148 #[track_caller]
1149 pub const fn strict_sub(self, rhs: Self) -> Self {
1150 let (a, b) = self.overflowing_sub(rhs);
1151 if b { imp::overflow_panic::sub() } else { a }
1152 }
1153
1154 /// Unchecked integer subtraction. Computes `self - rhs`, assuming overflow
1155 /// cannot occur.
1156 ///
1157 /// Calling `x.unchecked_sub(y)` is semantically equivalent to calling
1158 /// `x.`[`checked_sub`]`(y).`[`unwrap_unchecked`]`()`.
1159 ///
1160 /// If you're just trying to avoid the panic in debug mode, then **do not**
1161 /// use this. Instead, you're looking for [`wrapping_sub`].
1162 ///
1163 /// If you find yourself writing code like this:
1164 ///
1165 /// ```
1166 /// # let foo = 30_u32;
1167 /// # let bar = 20;
1168 /// if foo >= bar {
1169 /// // SAFETY: just checked it will not overflow
1170 /// let diff = unsafe { foo.unchecked_sub(bar) };
1171 /// // ... use diff ...
1172 /// }
1173 /// ```
1174 ///
1175 /// Consider changing it to
1176 ///
1177 /// ```
1178 /// # let foo = 30_u32;
1179 /// # let bar = 20;
1180 /// if let Some(diff) = foo.checked_sub(bar) {
1181 /// // ... use diff ...
1182 /// }
1183 /// ```
1184 ///
1185 /// As that does exactly the same thing -- including telling the optimizer
1186 /// that the subtraction cannot overflow -- but avoids needing `unsafe`.
1187 ///
1188 /// # Safety
1189 ///
1190 /// This results in undefined behavior when overflow occurs, i.e. when
1191 /// [`checked_sub`] would return `None`.
1192 ///
1193 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1194 #[doc = concat!("[`checked_sub`]: ", stringify!($SelfT), "::checked_sub")]
1195 #[doc = concat!("[`wrapping_sub`]: ", stringify!($SelfT), "::wrapping_sub")]
1196 #[stable(feature = "unchecked_math", since = "1.79.0")]
1197 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1198 #[must_use = "this returns the result of the operation, \
1199 without modifying the original"]
1200 #[inline(always)]
1201 #[track_caller]
1202 pub const unsafe fn unchecked_sub(self, rhs: Self) -> Self {
1203 assert_unsafe_precondition!(
1204 check_language_ub,
1205 concat!(stringify!($SelfT), "::unchecked_sub cannot overflow"),
1206 (
1207 lhs: $SelfT = self,
1208 rhs: $SelfT = rhs,
1209 ) => !lhs.overflowing_sub(rhs).1,
1210 );
1211
1212 // SAFETY: this is guaranteed to be safe by the caller.
1213 unsafe {
1214 intrinsics::unchecked_sub(self, rhs)
1215 }
1216 }
1217
1218 /// Checked subtraction with a signed integer. Computes `self - rhs`,
1219 /// returning `None` if overflow occurred.
1220 ///
1221 /// # Examples
1222 ///
1223 /// ```
1224 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(2), None);")]
1225 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_sub_signed(-2), Some(3));")]
1226 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).checked_sub_signed(-4), None);")]
1227 /// ```
1228 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1229 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
1230 #[must_use = "this returns the result of the operation, \
1231 without modifying the original"]
1232 #[inline]
1233 pub const fn checked_sub_signed(self, rhs: $SignedT) -> Option<Self> {
1234 let (res, overflow) = self.overflowing_sub_signed(rhs);
1235
1236 if !overflow {
1237 Some(res)
1238 } else {
1239 None
1240 }
1241 }
1242
1243 /// Strict subtraction with a signed integer. Computes `self - rhs`,
1244 /// panicking if overflow occurred.
1245 ///
1246 /// # Panics
1247 ///
1248 /// ## Overflow behavior
1249 ///
1250 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1251 ///
1252 /// # Examples
1253 ///
1254 /// ```
1255 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".strict_sub_signed(2), 1);")]
1256 /// ```
1257 ///
1258 /// The following panic because of overflow:
1259 ///
1260 /// ```should_panic
1261 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_sub_signed(2);")]
1262 /// ```
1263 ///
1264 /// ```should_panic
1265 #[doc = concat!("let _ = (", stringify!($SelfT), "::MAX).strict_sub_signed(-1);")]
1266 /// ```
1267 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1268 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1269 #[must_use = "this returns the result of the operation, \
1270 without modifying the original"]
1271 #[inline]
1272 #[track_caller]
1273 pub const fn strict_sub_signed(self, rhs: $SignedT) -> Self {
1274 let (a, b) = self.overflowing_sub_signed(rhs);
1275 if b { imp::overflow_panic::sub() } else { a }
1276 }
1277
1278 #[doc = concat!(
1279 "Checked integer subtraction. Computes `self - rhs` and checks if the result fits into an [`",
1280 stringify!($SignedT), "`], returning `None` if overflow occurred."
1281 )]
1282 ///
1283 /// # Examples
1284 ///
1285 /// ```
1286 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_signed_diff(2), Some(8));")]
1287 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_signed_diff(10), Some(-8));")]
1288 #[doc = concat!(
1289 "assert_eq!(",
1290 stringify!($SelfT),
1291 "::MAX.checked_signed_diff(",
1292 stringify!($SignedT),
1293 "::MAX as ",
1294 stringify!($SelfT),
1295 "), None);"
1296 )]
1297 #[doc = concat!(
1298 "assert_eq!((",
1299 stringify!($SignedT),
1300 "::MAX as ",
1301 stringify!($SelfT),
1302 ").checked_signed_diff(",
1303 stringify!($SelfT),
1304 "::MAX), Some(",
1305 stringify!($SignedT),
1306 "::MIN));"
1307 )]
1308 #[doc = concat!(
1309 "assert_eq!((",
1310 stringify!($SignedT),
1311 "::MAX as ",
1312 stringify!($SelfT),
1313 " + 1).checked_signed_diff(0), None);"
1314 )]
1315 #[doc = concat!(
1316 "assert_eq!(",
1317 stringify!($SelfT),
1318 "::MAX.checked_signed_diff(",
1319 stringify!($SelfT),
1320 "::MAX), Some(0));"
1321 )]
1322 /// ```
1323 #[stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1324 #[rustc_const_stable(feature = "unsigned_signed_diff", since = "1.91.0")]
1325 #[inline]
1326 pub const fn checked_signed_diff(self, rhs: Self) -> Option<$SignedT> {
1327 let res = self.wrapping_sub(rhs) as $SignedT;
1328 let overflow = (self >= rhs) == (res < 0);
1329
1330 if !overflow {
1331 Some(res)
1332 } else {
1333 None
1334 }
1335 }
1336
1337 /// Checked integer multiplication. Computes `self * rhs`, returning
1338 /// `None` if overflow occurred.
1339 ///
1340 /// # Examples
1341 ///
1342 /// ```
1343 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_mul(1), Some(5));")]
1344 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_mul(2), None);")]
1345 /// ```
1346 #[stable(feature = "rust1", since = "1.0.0")]
1347 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1348 #[must_use = "this returns the result of the operation, \
1349 without modifying the original"]
1350 #[inline]
1351 pub const fn checked_mul(self, rhs: Self) -> Option<Self> {
1352 let (a, b) = self.overflowing_mul(rhs);
1353 if intrinsics::unlikely(b) { None } else { Some(a) }
1354 }
1355
1356 /// Strict integer multiplication. Computes `self * rhs`, panicking if
1357 /// overflow occurred.
1358 ///
1359 /// # Panics
1360 ///
1361 /// ## Overflow behavior
1362 ///
1363 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
1364 ///
1365 /// # Examples
1366 ///
1367 /// ```
1368 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".strict_mul(1), 5);")]
1369 /// ```
1370 ///
1371 /// The following panics because of overflow:
1372 ///
1373 /// ``` should_panic
1374 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_mul(2);")]
1375 /// ```
1376 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1377 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1378 #[must_use = "this returns the result of the operation, \
1379 without modifying the original"]
1380 #[inline]
1381 #[track_caller]
1382 pub const fn strict_mul(self, rhs: Self) -> Self {
1383 let (a, b) = self.overflowing_mul(rhs);
1384 if b { imp::overflow_panic::mul() } else { a }
1385 }
1386
1387 /// Unchecked integer multiplication. Computes `self * rhs`, assuming overflow
1388 /// cannot occur.
1389 ///
1390 /// Calling `x.unchecked_mul(y)` is semantically equivalent to calling
1391 /// `x.`[`checked_mul`]`(y).`[`unwrap_unchecked`]`()`.
1392 ///
1393 /// If you're just trying to avoid the panic in debug mode, then **do not**
1394 /// use this. Instead, you're looking for [`wrapping_mul`].
1395 ///
1396 /// # Safety
1397 ///
1398 /// This results in undefined behavior when overflow occurs, i.e. when
1399 /// [`checked_mul`] would return `None`.
1400 ///
1401 /// [`unwrap_unchecked`]: option/enum.Option.html#method.unwrap_unchecked
1402 #[doc = concat!("[`checked_mul`]: ", stringify!($SelfT), "::checked_mul")]
1403 #[doc = concat!("[`wrapping_mul`]: ", stringify!($SelfT), "::wrapping_mul")]
1404 #[stable(feature = "unchecked_math", since = "1.79.0")]
1405 #[rustc_const_stable(feature = "unchecked_math", since = "1.79.0")]
1406 #[must_use = "this returns the result of the operation, \
1407 without modifying the original"]
1408 #[inline(always)]
1409 #[track_caller]
1410 pub const unsafe fn unchecked_mul(self, rhs: Self) -> Self {
1411 assert_unsafe_precondition!(
1412 check_language_ub,
1413 concat!(stringify!($SelfT), "::unchecked_mul cannot overflow"),
1414 (
1415 lhs: $SelfT = self,
1416 rhs: $SelfT = rhs,
1417 ) => !lhs.overflowing_mul(rhs).1,
1418 );
1419
1420 // SAFETY: this is guaranteed to be safe by the caller.
1421 unsafe {
1422 intrinsics::unchecked_mul(self, rhs)
1423 }
1424 }
1425
1426 /// Checked integer division. Computes `self / rhs`, returning `None`
1427 /// if `rhs == 0`.
1428 ///
1429 /// # Examples
1430 ///
1431 /// ```
1432 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div(2), Some(64));")]
1433 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div(0), None);")]
1434 /// ```
1435 #[stable(feature = "rust1", since = "1.0.0")]
1436 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1437 #[must_use = "this returns the result of the operation, \
1438 without modifying the original"]
1439 #[inline]
1440 pub const fn checked_div(self, rhs: Self) -> Option<Self> {
1441 if intrinsics::unlikely(rhs == 0) {
1442 None
1443 } else {
1444 // SAFETY: div by zero has been checked above and unsigned types have no other
1445 // failure modes for division
1446 Some(unsafe { intrinsics::unchecked_div(self, rhs) })
1447 }
1448 }
1449
1450 /// Strict integer division. Computes `self / rhs`.
1451 ///
1452 /// Strict division on unsigned types is just normal division. There's no
1453 /// way overflow could ever happen. This function exists so that all
1454 /// operations are accounted for in the strict operations.
1455 ///
1456 /// # Panics
1457 ///
1458 /// This function will panic if `rhs` is zero.
1459 ///
1460 /// # Examples
1461 ///
1462 /// ```
1463 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div(10), 10);")]
1464 /// ```
1465 ///
1466 /// The following panics because of division by zero:
1467 ///
1468 /// ```should_panic
1469 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div(0);")]
1470 /// ```
1471 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1472 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1473 #[must_use = "this returns the result of the operation, \
1474 without modifying the original"]
1475 #[inline(always)]
1476 #[track_caller]
1477 pub const fn strict_div(self, rhs: Self) -> Self {
1478 self / rhs
1479 }
1480
1481 /// Checked Euclidean division. Computes `self.div_euclid(rhs)`, returning `None`
1482 /// if `rhs == 0`.
1483 ///
1484 /// # Examples
1485 ///
1486 /// ```
1487 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_div_euclid(2), Some(64));")]
1488 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_div_euclid(0), None);")]
1489 /// ```
1490 #[stable(feature = "euclidean_division", since = "1.38.0")]
1491 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1492 #[must_use = "this returns the result of the operation, \
1493 without modifying the original"]
1494 #[inline]
1495 pub const fn checked_div_euclid(self, rhs: Self) -> Option<Self> {
1496 if intrinsics::unlikely(rhs == 0) {
1497 None
1498 } else {
1499 Some(self.div_euclid(rhs))
1500 }
1501 }
1502
1503 /// Strict Euclidean division. Computes `self.div_euclid(rhs)`.
1504 ///
1505 /// Strict division on unsigned types is just normal division. There's no
1506 /// way overflow could ever happen. This function exists so that all
1507 /// operations are accounted for in the strict operations. Since, for the
1508 /// positive integers, all common definitions of division are equal, this
1509 /// is exactly equal to `self.strict_div(rhs)`.
1510 ///
1511 /// # Panics
1512 ///
1513 /// This function will panic if `rhs` is zero.
1514 ///
1515 /// # Examples
1516 ///
1517 /// ```
1518 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_div_euclid(10), 10);")]
1519 /// ```
1520 /// The following panics because of division by zero:
1521 ///
1522 /// ```should_panic
1523 #[doc = concat!("let _ = (1", stringify!($SelfT), ").strict_div_euclid(0);")]
1524 /// ```
1525 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1526 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1527 #[must_use = "this returns the result of the operation, \
1528 without modifying the original"]
1529 #[inline(always)]
1530 #[track_caller]
1531 pub const fn strict_div_euclid(self, rhs: Self) -> Self {
1532 self / rhs
1533 }
1534
1535 /// Checked integer division without remainder. Computes `self / rhs`,
1536 /// returning `None` if `rhs == 0` or if `self % rhs != 0`.
1537 ///
1538 /// # Examples
1539 ///
1540 /// ```
1541 /// #![feature(exact_div)]
1542 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(2), Some(32));")]
1543 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(32), Some(2));")]
1544 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".checked_div_exact(0), None);")]
1545 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".checked_div_exact(2), None);")]
1546 /// ```
1547 #[unstable(
1548 feature = "exact_div",
1549 issue = "139911",
1550 )]
1551 #[must_use = "this returns the result of the operation, \
1552 without modifying the original"]
1553 #[inline]
1554 pub const fn checked_div_exact(self, rhs: Self) -> Option<Self> {
1555 if intrinsics::unlikely(rhs == 0) {
1556 None
1557 } else {
1558 // SAFETY: division by zero is checked above
1559 unsafe {
1560 if intrinsics::unlikely(intrinsics::unchecked_rem(self, rhs) != 0) {
1561 None
1562 } else {
1563 Some(intrinsics::exact_div(self, rhs))
1564 }
1565 }
1566 }
1567 }
1568
1569 /// Integer division without remainder. Computes `self / rhs`, returning `None` if `self % rhs != 0`.
1570 ///
1571 /// # Panics
1572 ///
1573 /// This function will panic if `rhs == 0`.
1574 ///
1575 /// # Examples
1576 ///
1577 /// ```
1578 /// #![feature(exact_div)]
1579 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(2), Some(32));")]
1580 #[doc = concat!("assert_eq!(64", stringify!($SelfT), ".div_exact(32), Some(2));")]
1581 #[doc = concat!("assert_eq!(65", stringify!($SelfT), ".div_exact(2), None);")]
1582 /// ```
1583 #[unstable(
1584 feature = "exact_div",
1585 issue = "139911",
1586 )]
1587 #[must_use = "this returns the result of the operation, \
1588 without modifying the original"]
1589 #[inline]
1590 #[rustc_inherit_overflow_checks]
1591 pub const fn div_exact(self, rhs: Self) -> Option<Self> {
1592 if self % rhs != 0 {
1593 None
1594 } else {
1595 Some(self / rhs)
1596 }
1597 }
1598
1599 /// Unchecked integer division without remainder. Computes `self / rhs`.
1600 ///
1601 /// # Safety
1602 ///
1603 /// This results in undefined behavior when `rhs == 0` or `self % rhs != 0`,
1604 /// i.e. when [`checked_div_exact`](Self::checked_div_exact) would return `None`.
1605 #[unstable(
1606 feature = "exact_div",
1607 issue = "139911",
1608 )]
1609 #[must_use = "this returns the result of the operation, \
1610 without modifying the original"]
1611 #[inline]
1612 pub const unsafe fn unchecked_div_exact(self, rhs: Self) -> Self {
1613 assert_unsafe_precondition!(
1614 check_language_ub,
1615 concat!(stringify!($SelfT), "::unchecked_div_exact divide by zero or leave a remainder"),
1616 (
1617 lhs: $SelfT = self,
1618 rhs: $SelfT = rhs,
1619 ) => rhs > 0 && lhs % rhs == 0,
1620 );
1621 // SAFETY: Same precondition
1622 unsafe { intrinsics::exact_div(self, rhs) }
1623 }
1624
1625 /// Checked integer remainder. Computes `self % rhs`, returning `None`
1626 /// if `rhs == 0`.
1627 ///
1628 /// # Examples
1629 ///
1630 /// ```
1631 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(2), Some(1));")]
1632 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem(0), None);")]
1633 /// ```
1634 #[stable(feature = "wrapping", since = "1.7.0")]
1635 #[rustc_const_stable(feature = "const_checked_int_div", since = "1.52.0")]
1636 #[must_use = "this returns the result of the operation, \
1637 without modifying the original"]
1638 #[inline]
1639 pub const fn checked_rem(self, rhs: Self) -> Option<Self> {
1640 if intrinsics::unlikely(rhs == 0) {
1641 None
1642 } else {
1643 // SAFETY: div by zero has been checked above and unsigned types have no other
1644 // failure modes for division
1645 Some(unsafe { intrinsics::unchecked_rem(self, rhs) })
1646 }
1647 }
1648
1649 /// Strict integer remainder. Computes `self % rhs`.
1650 ///
1651 /// Strict remainder calculation on unsigned types is just the regular
1652 /// remainder calculation. There's no way overflow could ever happen.
1653 /// This function exists so that all operations are accounted for in the
1654 /// strict operations.
1655 ///
1656 /// # Panics
1657 ///
1658 /// This function will panic if `rhs` is zero.
1659 ///
1660 /// # Examples
1661 ///
1662 /// ```
1663 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem(10), 0);")]
1664 /// ```
1665 ///
1666 /// The following panics because of division by zero:
1667 ///
1668 /// ```should_panic
1669 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem(0);")]
1670 /// ```
1671 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1672 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1673 #[must_use = "this returns the result of the operation, \
1674 without modifying the original"]
1675 #[inline(always)]
1676 #[track_caller]
1677 pub const fn strict_rem(self, rhs: Self) -> Self {
1678 self % rhs
1679 }
1680
1681 /// Checked Euclidean modulo. Computes `self.rem_euclid(rhs)`, returning `None`
1682 /// if `rhs == 0`.
1683 ///
1684 /// # Examples
1685 ///
1686 /// ```
1687 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(2), Some(1));")]
1688 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_rem_euclid(0), None);")]
1689 /// ```
1690 #[stable(feature = "euclidean_division", since = "1.38.0")]
1691 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
1692 #[must_use = "this returns the result of the operation, \
1693 without modifying the original"]
1694 #[inline]
1695 pub const fn checked_rem_euclid(self, rhs: Self) -> Option<Self> {
1696 if intrinsics::unlikely(rhs == 0) {
1697 None
1698 } else {
1699 Some(self.rem_euclid(rhs))
1700 }
1701 }
1702
1703 /// Strict Euclidean modulo. Computes `self.rem_euclid(rhs)`.
1704 ///
1705 /// Strict modulo calculation on unsigned types is just the regular
1706 /// remainder calculation. There's no way overflow could ever happen.
1707 /// This function exists so that all operations are accounted for in the
1708 /// strict operations. Since, for the positive integers, all common
1709 /// definitions of division are equal, this is exactly equal to
1710 /// `self.strict_rem(rhs)`.
1711 ///
1712 /// # Panics
1713 ///
1714 /// This function will panic if `rhs` is zero.
1715 ///
1716 /// # Examples
1717 ///
1718 /// ```
1719 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".strict_rem_euclid(10), 0);")]
1720 /// ```
1721 ///
1722 /// The following panics because of division by zero:
1723 ///
1724 /// ```should_panic
1725 #[doc = concat!("let _ = 5", stringify!($SelfT), ".strict_rem_euclid(0);")]
1726 /// ```
1727 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
1728 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
1729 #[must_use = "this returns the result of the operation, \
1730 without modifying the original"]
1731 #[inline(always)]
1732 #[track_caller]
1733 pub const fn strict_rem_euclid(self, rhs: Self) -> Self {
1734 self % rhs
1735 }
1736
1737 /// Disjoint, bitwise or. Computes `self | rhs`, assuming no overlapping one bits.
1738 ///
1739 /// Practically, this requires that `self | rhs`, `self ^ rhs`, and `self + rhs` all
1740 /// yield the same result, allowing for any of the three to be emitted in codegen --
1741 /// depending on whichever is cheapest.
1742 ///
1743 /// # Examples
1744 ///
1745 /// ```
1746 /// #![feature(disjoint_bitor)]
1747 ///
1748 /// assert_eq!(
1749 /// // SAFETY: `1` and `4` have no ones in common.
1750 #[doc = concat!(" unsafe { 1_", stringify!($SelfT), ".unchecked_disjoint_bitor(4) },")]
1751 /// 5,
1752 /// );
1753 /// ```
1754 ///
1755 /// # Safety
1756 ///
1757 /// This results in undefined behaviour if `self` and `rhs` have any overlapping one
1758 /// bits, i.e. `lhs & rhs` must be zero.
1759 #[unstable(feature = "disjoint_bitor", issue = "135758")]
1760 #[rustc_const_unstable(feature = "disjoint_bitor", issue = "135758")]
1761 #[must_use = "this returns the result of the operation, \
1762 without modifying the original"]
1763 #[inline]
1764 pub const unsafe fn unchecked_disjoint_bitor(self, rhs: Self) -> Self {
1765 assert_unsafe_precondition!(
1766 check_language_ub,
1767 concat!(stringify!($SelfT), "::unchecked_disjoint_bitor cannot bitor overlapping ones"),
1768 (
1769 lhs: $SelfT = self,
1770 rhs: $SelfT = rhs,
1771 ) => (lhs & rhs) == 0,
1772 );
1773
1774 // SAFETY: Same precondition.
1775 unsafe { intrinsics::disjoint_bitor(self, rhs) }
1776 }
1777
1778 /// Returns the logarithm of the number with respect to an arbitrary base,
1779 /// rounded down.
1780 ///
1781 /// This method might not be optimized owing to implementation details;
1782 /// [`ilog2`](Self::ilog2) can produce results more efficiently for base 2,
1783 /// and [`ilog10`](Self::ilog10) can produce results more efficiently for base 10.
1784 ///
1785 /// # Panics
1786 ///
1787 /// This function will panic if `self` is zero, or if `base` is less than 2.
1788 ///
1789 /// # Examples
1790 ///
1791 /// ```
1792 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".ilog(5), 1);")]
1793 /// ```
1794 #[stable(feature = "int_log", since = "1.67.0")]
1795 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1796 #[must_use = "this returns the result of the operation, \
1797 without modifying the original"]
1798 #[inline]
1799 #[track_caller]
1800 pub const fn ilog(self, base: Self) -> u32 {
1801 assert!(base >= 2, "base of integer logarithm must be at least 2");
1802 if let Some(log) = self.checked_ilog(base) {
1803 log
1804 } else {
1805 imp::int_log10::panic_for_nonpositive_argument()
1806 }
1807 }
1808
1809 /// Returns the base 2 logarithm of the number, rounded down.
1810 ///
1811 /// # Panics
1812 ///
1813 /// This function will panic if `self` is zero.
1814 ///
1815 /// # Examples
1816 ///
1817 /// ```
1818 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".ilog2(), 1);")]
1819 /// ```
1820 #[stable(feature = "int_log", since = "1.67.0")]
1821 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1822 #[must_use = "this returns the result of the operation, \
1823 without modifying the original"]
1824 #[inline]
1825 #[track_caller]
1826 pub const fn ilog2(self) -> u32 {
1827 if let Some(log) = self.checked_ilog2() {
1828 log
1829 } else {
1830 imp::int_log10::panic_for_nonpositive_argument()
1831 }
1832 }
1833
1834 /// Returns the base 10 logarithm of the number, rounded down.
1835 ///
1836 /// # Panics
1837 ///
1838 /// This function will panic if `self` is zero.
1839 ///
1840 /// # Example
1841 ///
1842 /// ```
1843 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".ilog10(), 1);")]
1844 /// ```
1845 #[stable(feature = "int_log", since = "1.67.0")]
1846 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1847 #[must_use = "this returns the result of the operation, \
1848 without modifying the original"]
1849 #[inline]
1850 #[track_caller]
1851 pub const fn ilog10(self) -> u32 {
1852 if let Some(log) = self.checked_ilog10() {
1853 log
1854 } else {
1855 imp::int_log10::panic_for_nonpositive_argument()
1856 }
1857 }
1858
1859 /// Returns the logarithm of the number with respect to an arbitrary base,
1860 /// rounded down.
1861 ///
1862 /// Returns `None` if the number is zero, or if the base is not at least 2.
1863 ///
1864 /// This method might not be optimized owing to implementation details;
1865 /// `checked_ilog2` can produce results more efficiently for base 2, and
1866 /// `checked_ilog10` can produce results more efficiently for base 10.
1867 ///
1868 /// # Examples
1869 ///
1870 /// ```
1871 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(5), Some(1));")]
1872 #[doc = concat!("assert_eq!(4", stringify!($SelfT), ".checked_ilog(5), Some(0));")]
1873 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(0), None);")]
1874 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".checked_ilog(1), None);")]
1875 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_ilog(1), None);")]
1876 /// ```
1877 #[stable(feature = "int_log", since = "1.67.0")]
1878 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1879 #[must_use = "this returns the result of the operation, \
1880 without modifying the original"]
1881 #[inline]
1882 pub const fn checked_ilog(self, base: Self) -> Option<u32> {
1883 // Inform compiler of optimizations when the base is known at
1884 // compile time and there's a cheaper method available.
1885 //
1886 // Note: Like all optimizations, this is not guaranteed to be
1887 // applied by the compiler. If you want those specific bases,
1888 // use `.checked_ilog2()` or `.checked_ilog10()` directly.
1889 if core::intrinsics::is_val_statically_known(base) {
1890 // change of base:
1891 // if base == 2 ** k, then
1892 // log(base, n) == log(2, n) / k
1893 if base.is_power_of_two() && base > 1 {
1894 let k = base.ilog2();
1895 return Some(try_opt!(self.checked_ilog2()) / k);
1896 }
1897 if base == 10 {
1898 return self.checked_ilog10();
1899 }
1900 }
1901
1902 if self <= 0 || base <= 1 {
1903 None
1904 } else if self < base {
1905 Some(0)
1906 } else {
1907 // Since base >= self, n >= 1
1908 let mut n = 1;
1909 let mut r = base;
1910
1911 // Optimization for 128 bit wide integers.
1912 if Self::BITS == 128 {
1913 // The following is a correct lower bound for ⌊log(base,self)⌋ because
1914 //
1915 // log(base,self) = log(2,self) / log(2,base)
1916 // ≥ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1)
1917 //
1918 // hence
1919 //
1920 // ⌊log(base,self)⌋ ≥ ⌊ ⌊log(2,self)⌋ / (⌊log(2,base)⌋ + 1) ⌋ .
1921 n = self.ilog2() / (base.ilog2() + 1);
1922 r = base.pow(n);
1923 }
1924
1925 while r <= self / base {
1926 n += 1;
1927 r *= base;
1928 }
1929 Some(n)
1930 }
1931 }
1932
1933 /// Returns the base 2 logarithm of the number, rounded down.
1934 ///
1935 /// Returns `None` if the number is zero.
1936 ///
1937 /// Note that this is equivalent to [`highest_one`](Self::highest_one).
1938 ///
1939 /// # Examples
1940 ///
1941 /// ```
1942 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_ilog2(), Some(1));")]
1943 /// ```
1944 #[stable(feature = "int_log", since = "1.67.0")]
1945 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1946 #[must_use = "this returns the result of the operation, \
1947 without modifying the original"]
1948 #[inline]
1949 pub const fn checked_ilog2(self) -> Option<u32> {
1950 match NonZero::new(self) {
1951 Some(x) => Some(x.ilog2()),
1952 None => None,
1953 }
1954 }
1955
1956 /// Returns the base 10 logarithm of the number, rounded down.
1957 ///
1958 /// Returns `None` if the number is zero.
1959 ///
1960 /// # Examples
1961 ///
1962 /// ```
1963 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_ilog10(), Some(1));")]
1964 /// ```
1965 #[stable(feature = "int_log", since = "1.67.0")]
1966 #[rustc_const_stable(feature = "int_log", since = "1.67.0")]
1967 #[must_use = "this returns the result of the operation, \
1968 without modifying the original"]
1969 #[inline]
1970 pub const fn checked_ilog10(self) -> Option<u32> {
1971 match NonZero::new(self) {
1972 Some(x) => Some(x.ilog10()),
1973 None => None,
1974 }
1975 }
1976
1977 /// Checked negation. Computes `-self`, returning `None` unless `self ==
1978 /// 0`.
1979 ///
1980 /// Note that negating any positive integer will overflow.
1981 ///
1982 /// # Examples
1983 ///
1984 /// ```
1985 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".checked_neg(), Some(0));")]
1986 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".checked_neg(), None);")]
1987 /// ```
1988 #[stable(feature = "wrapping", since = "1.7.0")]
1989 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
1990 #[must_use = "this returns the result of the operation, \
1991 without modifying the original"]
1992 #[inline]
1993 pub const fn checked_neg(self) -> Option<Self> {
1994 let (a, b) = self.overflowing_neg();
1995 if intrinsics::unlikely(b) { None } else { Some(a) }
1996 }
1997
1998 /// Strict negation. Computes `-self`, panicking unless `self ==
1999 /// 0`.
2000 ///
2001 /// Note that negating any positive integer will overflow.
2002 ///
2003 /// # Panics
2004 ///
2005 /// ## Overflow behavior
2006 ///
2007 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2008 ///
2009 /// # Examples
2010 ///
2011 /// ```
2012 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".strict_neg(), 0);")]
2013 /// ```
2014 ///
2015 /// The following panics because of overflow:
2016 ///
2017 /// ```should_panic
2018 #[doc = concat!("let _ = 1", stringify!($SelfT), ".strict_neg();")]
2019 /// ```
2020 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2021 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2022 #[must_use = "this returns the result of the operation, \
2023 without modifying the original"]
2024 #[inline]
2025 #[track_caller]
2026 pub const fn strict_neg(self) -> Self {
2027 let (a, b) = self.overflowing_neg();
2028 if b { imp::overflow_panic::neg() } else { a }
2029 }
2030
2031 /// Checked shift left. Computes `self << rhs`, returning `None`
2032 /// if `rhs` is larger than or equal to the number of bits in `self`.
2033 ///
2034 /// # Examples
2035 ///
2036 /// ```
2037 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".checked_shl(4), Some(0x10));")]
2038 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(129), None);")]
2039 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shl(", stringify!($BITS_MINUS_ONE), "), Some(0));")]
2040 /// ```
2041 #[stable(feature = "wrapping", since = "1.7.0")]
2042 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
2043 #[must_use = "this returns the result of the operation, \
2044 without modifying the original"]
2045 #[inline]
2046 pub const fn checked_shl(self, rhs: u32) -> Option<Self> {
2047 // Not using overflowing_shl as that's a wrapping shift
2048 if rhs < Self::BITS {
2049 // SAFETY: just checked the RHS is in-range
2050 Some(unsafe { self.unchecked_shl(rhs) })
2051 } else {
2052 None
2053 }
2054 }
2055
2056 /// Strict shift left. Computes `self << rhs`, panicking if `rhs` is larger
2057 /// than or equal to the number of bits in `self`.
2058 ///
2059 /// # Panics
2060 ///
2061 /// ## Overflow behavior
2062 ///
2063 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2064 ///
2065 /// # Examples
2066 ///
2067 /// ```
2068 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".strict_shl(4), 0x10);")]
2069 /// ```
2070 ///
2071 /// The following panics because of overflow:
2072 ///
2073 /// ```should_panic
2074 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shl(129);")]
2075 /// ```
2076 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2077 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2078 #[must_use = "this returns the result of the operation, \
2079 without modifying the original"]
2080 #[inline]
2081 #[track_caller]
2082 pub const fn strict_shl(self, rhs: u32) -> Self {
2083 let (a, b) = self.overflowing_shl(rhs);
2084 if b { imp::overflow_panic::shl() } else { a }
2085 }
2086
2087 /// Unchecked shift left. Computes `self << rhs`, assuming that
2088 /// `rhs` is less than the number of bits in `self`.
2089 ///
2090 /// # Safety
2091 ///
2092 /// This results in undefined behavior if `rhs` is larger than
2093 /// or equal to the number of bits in `self`,
2094 /// i.e. when [`checked_shl`] would return `None`.
2095 ///
2096 #[doc = concat!("[`checked_shl`]: ", stringify!($SelfT), "::checked_shl")]
2097 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2098 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2099 #[must_use = "this returns the result of the operation, \
2100 without modifying the original"]
2101 #[inline(always)]
2102 #[track_caller]
2103 pub const unsafe fn unchecked_shl(self, rhs: u32) -> Self {
2104 assert_unsafe_precondition!(
2105 check_language_ub,
2106 concat!(stringify!($SelfT), "::unchecked_shl cannot overflow"),
2107 (
2108 rhs: u32 = rhs,
2109 ) => rhs < <$ActualT>::BITS,
2110 );
2111
2112 // SAFETY: this is guaranteed to be safe by the caller.
2113 unsafe {
2114 intrinsics::unchecked_shl(self, rhs)
2115 }
2116 }
2117
2118 /// Unbounded shift left. Computes `self << rhs`, without bounding the value of `rhs`.
2119 ///
2120 /// If `rhs` is larger or equal to the number of bits in `self`,
2121 /// the entire value is shifted out, and `0` is returned.
2122 ///
2123 /// # Examples
2124 ///
2125 /// ```
2126 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(4), 0x10);")]
2127 #[doc = concat!("assert_eq!(0x1_", stringify!($SelfT), ".unbounded_shl(129), 0);")]
2128 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(0), 0b101);")]
2129 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(1), 0b1010);")]
2130 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".unbounded_shl(2), 0b10100);")]
2131 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(", stringify!($BITS), "), 0);")]
2132 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shl(1).unbounded_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2133 ///
2134 #[doc = concat!("let start : ", stringify!($SelfT), " = 13;")]
2135 /// let mut running = start;
2136 /// for i in 0..160 {
2137 /// // The unbounded shift left by i is the same as `<< 1` i times
2138 /// assert_eq!(running, start.unbounded_shl(i));
2139 /// // Which is not always the case for a wrapping shift
2140 #[doc = concat!(" assert_eq!(running == start.wrapping_shl(i), i < ", stringify!($BITS), ");")]
2141 ///
2142 /// running <<= 1;
2143 /// }
2144 /// ```
2145 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2146 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2147 #[must_use = "this returns the result of the operation, \
2148 without modifying the original"]
2149 #[inline]
2150 pub const fn unbounded_shl(self, rhs: u32) -> $SelfT{
2151 if rhs < Self::BITS {
2152 // SAFETY:
2153 // rhs is just checked to be in-range above
2154 unsafe { self.unchecked_shl(rhs) }
2155 } else {
2156 0
2157 }
2158 }
2159
2160 /// Exact shift left. Computes `self << rhs` as long as it can be reversed losslessly.
2161 ///
2162 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2163 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2164 /// Otherwise, returns `Some(self << rhs)`.
2165 ///
2166 /// # Examples
2167 ///
2168 /// ```
2169 /// #![feature(exact_bitshifts)]
2170 ///
2171 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(4), Some(0x10));")]
2172 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".shl_exact(129), None);")]
2173 /// ```
2174 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2175 #[must_use = "this returns the result of the operation, \
2176 without modifying the original"]
2177 #[inline]
2178 pub const fn shl_exact(self, rhs: u32) -> Option<$SelfT> {
2179 if rhs <= self.leading_zeros() && rhs < <$SelfT>::BITS {
2180 // SAFETY: rhs is checked above
2181 Some(unsafe { self.unchecked_shl(rhs) })
2182 } else {
2183 None
2184 }
2185 }
2186
2187 /// Unchecked exact shift left. Computes `self << rhs`, assuming the operation can be
2188 /// losslessly reversed `rhs` cannot be larger than
2189 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2190 ///
2191 /// # Safety
2192 ///
2193 /// This results in undefined behavior when `rhs > self.leading_zeros() || rhs >=
2194 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2195 /// i.e. when
2196 #[doc = concat!("[`", stringify!($SelfT), "::shl_exact`]")]
2197 /// would return `None`.
2198 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2199 #[must_use = "this returns the result of the operation, \
2200 without modifying the original"]
2201 #[inline]
2202 pub const unsafe fn unchecked_shl_exact(self, rhs: u32) -> $SelfT {
2203 assert_unsafe_precondition!(
2204 check_library_ub,
2205 concat!(stringify!($SelfT), "::unchecked_shl_exact cannot shift out non-zero bits"),
2206 (
2207 zeros: u32 = self.leading_zeros(),
2208 bits: u32 = <$SelfT>::BITS,
2209 rhs: u32 = rhs,
2210 ) => rhs <= zeros && rhs < bits,
2211 );
2212
2213 // SAFETY: this is guaranteed to be safe by the caller
2214 unsafe { self.unchecked_shl(rhs) }
2215 }
2216
2217 /// Checked shift right. Computes `self >> rhs`, returning `None`
2218 /// if `rhs` is larger than or equal to the number of bits in `self`.
2219 ///
2220 /// # Examples
2221 ///
2222 /// ```
2223 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(4), Some(0x1));")]
2224 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".checked_shr(129), None);")]
2225 /// ```
2226 #[stable(feature = "wrapping", since = "1.7.0")]
2227 #[rustc_const_stable(feature = "const_checked_int_methods", since = "1.47.0")]
2228 #[must_use = "this returns the result of the operation, \
2229 without modifying the original"]
2230 #[inline]
2231 pub const fn checked_shr(self, rhs: u32) -> Option<Self> {
2232 // Not using overflowing_shr as that's a wrapping shift
2233 if rhs < Self::BITS {
2234 // SAFETY: just checked the RHS is in-range
2235 Some(unsafe { self.unchecked_shr(rhs) })
2236 } else {
2237 None
2238 }
2239 }
2240
2241 /// Strict shift right. Computes `self >> rhs`, panicking if `rhs` is
2242 /// larger than or equal to the number of bits in `self`.
2243 ///
2244 /// # Panics
2245 ///
2246 /// ## Overflow behavior
2247 ///
2248 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2249 ///
2250 /// # Examples
2251 ///
2252 /// ```
2253 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".strict_shr(4), 0x1);")]
2254 /// ```
2255 ///
2256 /// The following panics because of overflow:
2257 ///
2258 /// ```should_panic
2259 #[doc = concat!("let _ = 0x10", stringify!($SelfT), ".strict_shr(129);")]
2260 /// ```
2261 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2262 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2263 #[must_use = "this returns the result of the operation, \
2264 without modifying the original"]
2265 #[inline]
2266 #[track_caller]
2267 pub const fn strict_shr(self, rhs: u32) -> Self {
2268 let (a, b) = self.overflowing_shr(rhs);
2269 if b { imp::overflow_panic::shr() } else { a }
2270 }
2271
2272 /// Unchecked shift right. Computes `self >> rhs`, assuming that
2273 /// `rhs` is less than the number of bits in `self`.
2274 ///
2275 /// # Safety
2276 ///
2277 /// This results in undefined behavior if `rhs` is larger than
2278 /// or equal to the number of bits in `self`,
2279 /// i.e. when [`checked_shr`] would return `None`.
2280 ///
2281 #[doc = concat!("[`checked_shr`]: ", stringify!($SelfT), "::checked_shr")]
2282 #[stable(feature = "unchecked_shifts", since = "1.93.0")]
2283 #[rustc_const_stable(feature = "unchecked_shifts", since = "1.93.0")]
2284 #[must_use = "this returns the result of the operation, \
2285 without modifying the original"]
2286 #[inline(always)]
2287 #[track_caller]
2288 pub const unsafe fn unchecked_shr(self, rhs: u32) -> Self {
2289 assert_unsafe_precondition!(
2290 check_language_ub,
2291 concat!(stringify!($SelfT), "::unchecked_shr cannot overflow"),
2292 (
2293 rhs: u32 = rhs,
2294 ) => rhs < <$ActualT>::BITS,
2295 );
2296
2297 // SAFETY: this is guaranteed to be safe by the caller.
2298 unsafe {
2299 intrinsics::unchecked_shr(self, rhs)
2300 }
2301 }
2302
2303 /// Unbounded shift right. Computes `self >> rhs`, without bounding the value of `rhs`.
2304 ///
2305 /// If `rhs` is larger or equal to the number of bits in `self`,
2306 /// the entire value is shifted out, and `0` is returned.
2307 ///
2308 /// # Examples
2309 ///
2310 /// ```
2311 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(4), 0x1);")]
2312 #[doc = concat!("assert_eq!(0x10_", stringify!($SelfT), ".unbounded_shr(129), 0);")]
2313 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(0), 0b1010);")]
2314 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(1), 0b101);")]
2315 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".unbounded_shr(2), 0b10);")]
2316 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(", stringify!($BITS), "), 0);")]
2317 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".unbounded_shr(1).unbounded_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2318 ///
2319 #[doc = concat!("let start = ", stringify!($SelfT), "::rotate_right(13, 4);")]
2320 /// let mut running = start;
2321 /// for i in 0..160 {
2322 /// // The unbounded shift right by i is the same as `>> 1` i times
2323 /// assert_eq!(running, start.unbounded_shr(i));
2324 /// // Which is not always the case for a wrapping shift
2325 #[doc = concat!(" assert_eq!(running == start.wrapping_shr(i), i < ", stringify!($BITS), ");")]
2326 ///
2327 /// running >>= 1;
2328 /// }
2329 /// ```
2330 #[stable(feature = "unbounded_shifts", since = "1.87.0")]
2331 #[rustc_const_stable(feature = "unbounded_shifts", since = "1.87.0")]
2332 #[must_use = "this returns the result of the operation, \
2333 without modifying the original"]
2334 #[inline]
2335 pub const fn unbounded_shr(self, rhs: u32) -> $SelfT{
2336 if rhs < Self::BITS {
2337 // SAFETY:
2338 // rhs is just checked to be in-range above
2339 unsafe { self.unchecked_shr(rhs) }
2340 } else {
2341 0
2342 }
2343 }
2344
2345 /// Exact shift right. Computes `self >> rhs` as long as it can be reversed losslessly.
2346 ///
2347 /// Returns `None` if any non-zero bits would be shifted out or if `rhs` >=
2348 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2349 /// Otherwise, returns `Some(self >> rhs)`.
2350 ///
2351 /// # Examples
2352 ///
2353 /// ```
2354 /// #![feature(exact_bitshifts)]
2355 ///
2356 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(4), Some(0x1));")]
2357 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".shr_exact(5), None);")]
2358 /// ```
2359 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2360 #[must_use = "this returns the result of the operation, \
2361 without modifying the original"]
2362 #[inline]
2363 pub const fn shr_exact(self, rhs: u32) -> Option<$SelfT> {
2364 if rhs <= self.trailing_zeros() && rhs < <$SelfT>::BITS {
2365 // SAFETY: rhs is checked above
2366 Some(unsafe { self.unchecked_shr(rhs) })
2367 } else {
2368 None
2369 }
2370 }
2371
2372 /// Unchecked exact shift right. Computes `self >> rhs`, assuming the operation can be
2373 /// losslessly reversed and `rhs` cannot be larger than
2374 #[doc = concat!("`", stringify!($SelfT), "::BITS`.")]
2375 ///
2376 /// # Safety
2377 ///
2378 /// This results in undefined behavior when `rhs > self.trailing_zeros() || rhs >=
2379 #[doc = concat!(stringify!($SelfT), "::BITS`")]
2380 /// i.e. when
2381 #[doc = concat!("[`", stringify!($SelfT), "::shr_exact`]")]
2382 /// would return `None`.
2383 #[unstable(feature = "exact_bitshifts", issue = "144336")]
2384 #[must_use = "this returns the result of the operation, \
2385 without modifying the original"]
2386 #[inline]
2387 pub const unsafe fn unchecked_shr_exact(self, rhs: u32) -> $SelfT {
2388 assert_unsafe_precondition!(
2389 check_library_ub,
2390 concat!(stringify!($SelfT), "::unchecked_shr_exact cannot shift out non-zero bits"),
2391 (
2392 zeros: u32 = self.trailing_zeros(),
2393 bits: u32 = <$SelfT>::BITS,
2394 rhs: u32 = rhs,
2395 ) => rhs <= zeros && rhs < bits,
2396 );
2397
2398 // SAFETY: this is guaranteed to be safe by the caller
2399 unsafe { self.unchecked_shr(rhs) }
2400 }
2401
2402 /// Checked exponentiation. Computes `self.pow(exp)`, returning `None` if
2403 /// overflow occurred.
2404 ///
2405 /// # Examples
2406 ///
2407 /// ```
2408 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_pow(5), Some(32));")]
2409 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".checked_pow(0), Some(1));")]
2410 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_pow(2), None);")]
2411 /// ```
2412 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2413 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2414 #[must_use = "this returns the result of the operation, \
2415 without modifying the original"]
2416 #[inline]
2417 pub const fn checked_pow(self, mut exp: u32) -> Option<Self> {
2418 let mut base = self;
2419 let mut acc: Self = 1;
2420
2421 if intrinsics::is_val_statically_known(base) && base.is_power_of_two() {
2422 // change of base:
2423 // if base == 2 ** k, then
2424 // (2 ** k) ** n
2425 // == 2 ** (k * n)
2426 // == 1 << (k * n)
2427 let k = base.ilog2();
2428 let shift = try_opt!(k.checked_mul(exp));
2429 return (1 as Self).checked_shl(shift);
2430 }
2431
2432 if exp == 0 {
2433 return Some(1);
2434 }
2435
2436 if intrinsics::is_val_statically_known(exp) {
2437 while exp > 1 {
2438 if (exp & 1) == 1 {
2439 acc = try_opt!(acc.checked_mul(base));
2440 }
2441 exp /= 2;
2442 base = try_opt!(base.checked_mul(base));
2443 }
2444
2445 // since exp!=0, finally the exp must be 1.
2446 // Deal with the final bit of the exponent separately, since
2447 // squaring the base afterwards is not necessary and may cause a
2448 // needless overflow.
2449 return acc.checked_mul(base);
2450 }
2451
2452 loop {
2453 if (exp & 1) == 1 {
2454 acc = try_opt!(acc.checked_mul(base));
2455 // since exp!=0, finally the exp must be 1.
2456 if exp == 1 {
2457 return Some(acc);
2458 }
2459 }
2460 exp /= 2;
2461 base = try_opt!(base.checked_mul(base));
2462 }
2463 }
2464
2465 /// Strict exponentiation. Computes `self.pow(exp)`, panicking if
2466 /// overflow occurred.
2467 ///
2468 /// # Panics
2469 ///
2470 /// ## Overflow behavior
2471 ///
2472 /// This function will always panic on overflow, regardless of whether overflow checks are enabled.
2473 ///
2474 /// # Examples
2475 ///
2476 /// ```
2477 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".strict_pow(5), 32);")]
2478 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".strict_pow(0), 1);")]
2479 /// ```
2480 ///
2481 /// The following panics because of overflow:
2482 ///
2483 /// ```should_panic
2484 #[doc = concat!("let _ = ", stringify!($SelfT), "::MAX.strict_pow(2);")]
2485 /// ```
2486 #[stable(feature = "strict_overflow_ops", since = "1.91.0")]
2487 #[rustc_const_stable(feature = "strict_overflow_ops", since = "1.91.0")]
2488 #[must_use = "this returns the result of the operation, \
2489 without modifying the original"]
2490 #[inline]
2491 #[track_caller]
2492 pub const fn strict_pow(self, exp: u32) -> Self {
2493 match self.checked_pow(exp) {
2494 None => imp::overflow_panic::pow(),
2495 Some(a) => a,
2496 }
2497 }
2498
2499 /// Saturating integer addition. Computes `self + rhs`, saturating at
2500 /// the numeric bounds instead of overflowing.
2501 ///
2502 /// # Examples
2503 ///
2504 /// ```
2505 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_add(1), 101);")]
2506 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_add(127), ", stringify!($SelfT), "::MAX);")]
2507 /// ```
2508 #[stable(feature = "rust1", since = "1.0.0")]
2509 #[must_use = "this returns the result of the operation, \
2510 without modifying the original"]
2511 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2512 #[inline(always)]
2513 pub const fn saturating_add(self, rhs: Self) -> Self {
2514 intrinsics::saturating_add(self, rhs)
2515 }
2516
2517 /// Saturating addition with a signed integer. Computes `self + rhs`,
2518 /// saturating at the numeric bounds instead of overflowing.
2519 ///
2520 /// # Examples
2521 ///
2522 /// ```
2523 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(2), 3);")]
2524 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_add_signed(-2), 0);")]
2525 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_add_signed(4), ", stringify!($SelfT), "::MAX);")]
2526 /// ```
2527 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2528 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2529 #[must_use = "this returns the result of the operation, \
2530 without modifying the original"]
2531 #[inline]
2532 pub const fn saturating_add_signed(self, rhs: $SignedT) -> Self {
2533 let (res, overflow) = self.overflowing_add(rhs as Self);
2534 if overflow == (rhs < 0) {
2535 res
2536 } else if overflow {
2537 Self::MAX
2538 } else {
2539 0
2540 }
2541 }
2542
2543 /// Saturating integer subtraction. Computes `self - rhs`, saturating
2544 /// at the numeric bounds instead of overflowing.
2545 ///
2546 /// # Examples
2547 ///
2548 /// ```
2549 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".saturating_sub(27), 73);")]
2550 #[doc = concat!("assert_eq!(13", stringify!($SelfT), ".saturating_sub(127), 0);")]
2551 /// ```
2552 #[stable(feature = "rust1", since = "1.0.0")]
2553 #[must_use = "this returns the result of the operation, \
2554 without modifying the original"]
2555 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2556 #[inline(always)]
2557 pub const fn saturating_sub(self, rhs: Self) -> Self {
2558 intrinsics::saturating_sub(self, rhs)
2559 }
2560
2561 /// Saturating integer subtraction. Computes `self` - `rhs`, saturating at
2562 /// the numeric bounds instead of overflowing.
2563 ///
2564 /// # Examples
2565 ///
2566 /// ```
2567 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(2), 0);")]
2568 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".saturating_sub_signed(-2), 3);")]
2569 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).saturating_sub_signed(-4), ", stringify!($SelfT), "::MAX);")]
2570 /// ```
2571 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2572 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2573 #[must_use = "this returns the result of the operation, \
2574 without modifying the original"]
2575 #[inline]
2576 pub const fn saturating_sub_signed(self, rhs: $SignedT) -> Self {
2577 let (res, overflow) = self.overflowing_sub_signed(rhs);
2578
2579 if !overflow {
2580 res
2581 } else if rhs < 0 {
2582 Self::MAX
2583 } else {
2584 0
2585 }
2586 }
2587
2588 /// Saturating integer multiplication. Computes `self * rhs`,
2589 /// saturating at the numeric bounds instead of overflowing.
2590 ///
2591 /// # Examples
2592 ///
2593 /// ```
2594 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".saturating_mul(10), 20);")]
2595 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX).saturating_mul(10), ", stringify!($SelfT),"::MAX);")]
2596 /// ```
2597 #[stable(feature = "wrapping", since = "1.7.0")]
2598 #[rustc_const_stable(feature = "const_saturating_int_methods", since = "1.47.0")]
2599 #[must_use = "this returns the result of the operation, \
2600 without modifying the original"]
2601 #[inline]
2602 pub const fn saturating_mul(self, rhs: Self) -> Self {
2603 match self.checked_mul(rhs) {
2604 Some(x) => x,
2605 None => Self::MAX,
2606 }
2607 }
2608
2609 /// Saturating integer division. Computes `self / rhs`, saturating at the
2610 /// numeric bounds instead of overflowing.
2611 ///
2612 /// # Panics
2613 ///
2614 /// This function will panic if `rhs` is zero.
2615 ///
2616 /// # Examples
2617 ///
2618 /// ```
2619 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".saturating_div(2), 2);")]
2620 ///
2621 /// ```
2622 #[stable(feature = "saturating_div", since = "1.58.0")]
2623 #[rustc_const_stable(feature = "saturating_div", since = "1.58.0")]
2624 #[must_use = "this returns the result of the operation, \
2625 without modifying the original"]
2626 #[inline]
2627 #[track_caller]
2628 pub const fn saturating_div(self, rhs: Self) -> Self {
2629 // on unsigned types, there is no overflow in integer division
2630 self.wrapping_div(rhs)
2631 }
2632
2633 /// Saturating integer exponentiation. Computes `self.pow(exp)`,
2634 /// saturating at the numeric bounds instead of overflowing.
2635 ///
2636 /// # Examples
2637 ///
2638 /// ```
2639 #[doc = concat!("assert_eq!(4", stringify!($SelfT), ".saturating_pow(3), 64);")]
2640 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".saturating_pow(0), 1);")]
2641 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_pow(2), ", stringify!($SelfT), "::MAX);")]
2642 /// ```
2643 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2644 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2645 #[must_use = "this returns the result of the operation, \
2646 without modifying the original"]
2647 #[inline]
2648 pub const fn saturating_pow(self, exp: u32) -> Self {
2649 match self.checked_pow(exp) {
2650 Some(x) => x,
2651 None => Self::MAX,
2652 }
2653 }
2654
2655 /// Wrapping (modular) addition. Computes `self + rhs`,
2656 /// wrapping around at the boundary of the type.
2657 ///
2658 /// # Examples
2659 ///
2660 /// ```
2661 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(55), 255);")]
2662 #[doc = concat!("assert_eq!(200", stringify!($SelfT), ".wrapping_add(", stringify!($SelfT), "::MAX), 199);")]
2663 /// ```
2664 #[stable(feature = "rust1", since = "1.0.0")]
2665 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2666 #[must_use = "this returns the result of the operation, \
2667 without modifying the original"]
2668 #[inline(always)]
2669 pub const fn wrapping_add(self, rhs: Self) -> Self {
2670 intrinsics::wrapping_add(self, rhs)
2671 }
2672
2673 /// Wrapping (modular) addition with a signed integer. Computes
2674 /// `self + rhs`, wrapping around at the boundary of the type.
2675 ///
2676 /// # Examples
2677 ///
2678 /// ```
2679 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(2), 3);")]
2680 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_add_signed(-2), ", stringify!($SelfT), "::MAX);")]
2681 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_add_signed(4), 1);")]
2682 /// ```
2683 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
2684 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
2685 #[must_use = "this returns the result of the operation, \
2686 without modifying the original"]
2687 #[inline]
2688 pub const fn wrapping_add_signed(self, rhs: $SignedT) -> Self {
2689 self.wrapping_add(rhs as Self)
2690 }
2691
2692 /// Wrapping (modular) subtraction. Computes `self - rhs`,
2693 /// wrapping around at the boundary of the type.
2694 ///
2695 /// # Examples
2696 ///
2697 /// ```
2698 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(100), 0);")]
2699 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_sub(", stringify!($SelfT), "::MAX), 101);")]
2700 /// ```
2701 #[stable(feature = "rust1", since = "1.0.0")]
2702 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2703 #[must_use = "this returns the result of the operation, \
2704 without modifying the original"]
2705 #[inline(always)]
2706 pub const fn wrapping_sub(self, rhs: Self) -> Self {
2707 intrinsics::wrapping_sub(self, rhs)
2708 }
2709
2710 /// Wrapping (modular) subtraction with a signed integer. Computes
2711 /// `self - rhs`, wrapping around at the boundary of the type.
2712 ///
2713 /// # Examples
2714 ///
2715 /// ```
2716 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(2), ", stringify!($SelfT), "::MAX);")]
2717 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".wrapping_sub_signed(-2), 3);")]
2718 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).wrapping_sub_signed(-4), 1);")]
2719 /// ```
2720 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2721 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
2722 #[must_use = "this returns the result of the operation, \
2723 without modifying the original"]
2724 #[inline]
2725 pub const fn wrapping_sub_signed(self, rhs: $SignedT) -> Self {
2726 self.wrapping_sub(rhs as Self)
2727 }
2728
2729 /// Wrapping (modular) multiplication. Computes `self *
2730 /// rhs`, wrapping around at the boundary of the type.
2731 ///
2732 /// # Examples
2733 ///
2734 /// Please note that this example is shared among integer types, which is why `u8` is used.
2735 ///
2736 /// ```
2737 /// assert_eq!(10u8.wrapping_mul(12), 120);
2738 /// assert_eq!(25u8.wrapping_mul(12), 44);
2739 /// ```
2740 #[stable(feature = "rust1", since = "1.0.0")]
2741 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2742 #[must_use = "this returns the result of the operation, \
2743 without modifying the original"]
2744 #[inline(always)]
2745 pub const fn wrapping_mul(self, rhs: Self) -> Self {
2746 intrinsics::wrapping_mul(self, rhs)
2747 }
2748
2749 /// Wrapping (modular) division. Computes `self / rhs`.
2750 ///
2751 /// Wrapped division on unsigned types is just normal division. There's
2752 /// no way wrapping could ever happen. This function exists so that all
2753 /// operations are accounted for in the wrapping operations.
2754 ///
2755 /// # Panics
2756 ///
2757 /// This function will panic if `rhs` is zero.
2758 ///
2759 /// # Examples
2760 ///
2761 /// ```
2762 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div(10), 10);")]
2763 /// ```
2764 #[stable(feature = "num_wrapping", since = "1.2.0")]
2765 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2766 #[must_use = "this returns the result of the operation, \
2767 without modifying the original"]
2768 #[inline(always)]
2769 #[track_caller]
2770 pub const fn wrapping_div(self, rhs: Self) -> Self {
2771 self / rhs
2772 }
2773
2774 /// Wrapping Euclidean division. Computes `self.div_euclid(rhs)`.
2775 ///
2776 /// Wrapped division on unsigned types is just normal division. There's
2777 /// no way wrapping could ever happen. This function exists so that all
2778 /// operations are accounted for in the wrapping operations. Since, for
2779 /// the positive integers, all common definitions of division are equal,
2780 /// this is exactly equal to `self.wrapping_div(rhs)`.
2781 ///
2782 /// # Panics
2783 ///
2784 /// This function will panic if `rhs` is zero.
2785 ///
2786 /// # Examples
2787 ///
2788 /// ```
2789 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_div_euclid(10), 10);")]
2790 /// ```
2791 #[stable(feature = "euclidean_division", since = "1.38.0")]
2792 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2793 #[must_use = "this returns the result of the operation, \
2794 without modifying the original"]
2795 #[inline(always)]
2796 #[track_caller]
2797 pub const fn wrapping_div_euclid(self, rhs: Self) -> Self {
2798 self / rhs
2799 }
2800
2801 /// Wrapping (modular) remainder. Computes `self % rhs`.
2802 ///
2803 /// Wrapped remainder calculation on unsigned types is just the regular
2804 /// remainder calculation. There's no way wrapping could ever happen.
2805 /// This function exists so that all operations are accounted for in the
2806 /// wrapping operations.
2807 ///
2808 /// # Panics
2809 ///
2810 /// This function will panic if `rhs` is zero.
2811 ///
2812 /// # Examples
2813 ///
2814 /// ```
2815 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem(10), 0);")]
2816 /// ```
2817 #[stable(feature = "num_wrapping", since = "1.2.0")]
2818 #[rustc_const_stable(feature = "const_wrapping_int_methods", since = "1.52.0")]
2819 #[must_use = "this returns the result of the operation, \
2820 without modifying the original"]
2821 #[inline(always)]
2822 #[track_caller]
2823 pub const fn wrapping_rem(self, rhs: Self) -> Self {
2824 self % rhs
2825 }
2826
2827 /// Wrapping Euclidean modulo. Computes `self.rem_euclid(rhs)`.
2828 ///
2829 /// Wrapped modulo calculation on unsigned types is just the regular
2830 /// remainder calculation. There's no way wrapping could ever happen.
2831 /// This function exists so that all operations are accounted for in the
2832 /// wrapping operations. Since, for the positive integers, all common
2833 /// definitions of division are equal, this is exactly equal to
2834 /// `self.wrapping_rem(rhs)`.
2835 ///
2836 /// # Panics
2837 ///
2838 /// This function will panic if `rhs` is zero.
2839 ///
2840 /// # Examples
2841 ///
2842 /// ```
2843 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".wrapping_rem_euclid(10), 0);")]
2844 /// ```
2845 #[stable(feature = "euclidean_division", since = "1.38.0")]
2846 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
2847 #[must_use = "this returns the result of the operation, \
2848 without modifying the original"]
2849 #[inline(always)]
2850 #[track_caller]
2851 pub const fn wrapping_rem_euclid(self, rhs: Self) -> Self {
2852 self % rhs
2853 }
2854
2855 /// Wrapping (modular) negation. Computes `-self`,
2856 /// wrapping around at the boundary of the type.
2857 ///
2858 /// Since unsigned types do not have negative equivalents
2859 /// all applications of this function will wrap (except for `-0`).
2860 /// For values smaller than the corresponding signed type's maximum
2861 /// the result is the same as casting the corresponding signed value.
2862 /// Any larger values are equivalent to `MAX + 1 - (val - MAX - 1)` where
2863 /// `MAX` is the corresponding signed type's maximum.
2864 ///
2865 /// # Examples
2866 ///
2867 /// ```
2868 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_neg(), 0);")]
2869 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_neg(), 1);")]
2870 #[doc = concat!("assert_eq!(13_", stringify!($SelfT), ".wrapping_neg(), (!13) + 1);")]
2871 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_neg(), !(42 - 1));")]
2872 /// ```
2873 #[stable(feature = "num_wrapping", since = "1.2.0")]
2874 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2875 #[must_use = "this returns the result of the operation, \
2876 without modifying the original"]
2877 #[inline(always)]
2878 pub const fn wrapping_neg(self) -> Self {
2879 (0 as $SelfT).wrapping_sub(self)
2880 }
2881
2882 /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
2883 /// where `mask` removes any high-order bits of `rhs` that
2884 /// would cause the shift to exceed the bitwidth of the type.
2885 ///
2886 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2887 /// does *not* give the same result as doing the shift in infinite precision
2888 /// then truncating as needed. Instead, the behaviour of this method matches what shift instructions
2889 /// do on many processors, and is what the `<<` operator does when overflow
2890 /// checks are disabled, but numerically it's weird. Consider, instead,
2891 /// using [`Self::unbounded_shl`] which has nicer behaviour.
2892 ///
2893 /// Note that this is *not* the same as a rotate-left; the
2894 /// RHS of a wrapping shift-left is restricted to the range
2895 /// of the type, rather than the bits shifted out of the LHS
2896 /// being returned to the other end. The primitive integer
2897 /// types all implement a [`rotate_left`](Self::rotate_left) function,
2898 /// which may be what you want instead.
2899 ///
2900 /// # Examples
2901 ///
2902 /// ```
2903 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(7), 128);")]
2904 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(0), 0b101);")]
2905 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(1), 0b1010);")]
2906 #[doc = concat!("assert_eq!(0b101_", stringify!($SelfT), ".wrapping_shl(2), 0b10100);")]
2907 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shl(2), ", stringify!($SelfT), "::MAX - 3);")]
2908 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(", stringify!($BITS), "), 42);")]
2909 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shl(1).wrapping_shl(", stringify!($BITS_MINUS_ONE), "), 0);")]
2910 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_shl(128), 1);")]
2911 #[doc = concat!("assert_eq!(5_", stringify!($SelfT), ".wrapping_shl(1025), 10);")]
2912 /// ```
2913 #[stable(feature = "num_wrapping", since = "1.2.0")]
2914 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2915 #[must_use = "this returns the result of the operation, \
2916 without modifying the original"]
2917 #[inline(always)]
2918 pub const fn wrapping_shl(self, rhs: u32) -> Self {
2919 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2920 // out of bounds
2921 unsafe {
2922 self.unchecked_shl(rhs & (Self::BITS - 1))
2923 }
2924 }
2925
2926 /// Panic-free bitwise shift-right; yields `self >> mask(rhs)`,
2927 /// where `mask` removes any high-order bits of `rhs` that
2928 /// would cause the shift to exceed the bitwidth of the type.
2929 ///
2930 /// Beware that, unlike most other `wrapping_*` methods on integers, this
2931 /// does *not* give the same result as doing the shift in infinite precision
2932 /// then truncating as needed. Instead, the behaviour of this method matches what shift instructions
2933 /// do on many processors, and is what the `>>` operator does when overflow
2934 /// checks are disabled, but numerically it's weird. Consider, instead,
2935 /// using [`Self::unbounded_shr`] which has nicer behaviour.
2936 ///
2937 /// Note that this is *not* the same as a rotate-right; the
2938 /// RHS of a wrapping shift-right is restricted to the range
2939 /// of the type, rather than the bits shifted out of the LHS
2940 /// being returned to the other end. The primitive integer
2941 /// types all implement a [`rotate_right`](Self::rotate_right) function,
2942 /// which may be what you want instead.
2943 ///
2944 /// # Examples
2945 ///
2946 /// ```
2947 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(7), 1);")]
2948 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(0), 0b1010);")]
2949 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(1), 0b101);")]
2950 #[doc = concat!("assert_eq!(0b1010_", stringify!($SelfT), ".wrapping_shr(2), 0b10);")]
2951 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_shr(1), ", stringify!($SignedT), "::MAX.cast_unsigned());")]
2952 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(", stringify!($BITS), "), 42);")]
2953 #[doc = concat!("assert_eq!(42_", stringify!($SelfT), ".wrapping_shr(1).wrapping_shr(", stringify!($BITS_MINUS_ONE), "), 0);")]
2954 #[doc = concat!("assert_eq!(128_", stringify!($SelfT), ".wrapping_shr(128), 128);")]
2955 #[doc = concat!("assert_eq!(10_", stringify!($SelfT), ".wrapping_shr(1025), 5);")]
2956 /// ```
2957 #[stable(feature = "num_wrapping", since = "1.2.0")]
2958 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
2959 #[must_use = "this returns the result of the operation, \
2960 without modifying the original"]
2961 #[inline(always)]
2962 pub const fn wrapping_shr(self, rhs: u32) -> Self {
2963 // SAFETY: the masking by the bitsize of the type ensures that we do not shift
2964 // out of bounds
2965 unsafe {
2966 self.unchecked_shr(rhs & (Self::BITS - 1))
2967 }
2968 }
2969
2970 /// Wrapping (modular) exponentiation. Computes `self.pow(exp)`,
2971 /// wrapping around at the boundary of the type.
2972 ///
2973 /// # Examples
2974 ///
2975 /// ```
2976 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_pow(5), 243);")]
2977 /// assert_eq!(3u8.wrapping_pow(6), 217);
2978 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_pow(0), 1);")]
2979 /// ```
2980 #[stable(feature = "no_panic_pow", since = "1.34.0")]
2981 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
2982 #[must_use = "this returns the result of the operation, \
2983 without modifying the original"]
2984 #[inline]
2985 pub const fn wrapping_pow(self, exp: u32) -> Self {
2986 let (a, _) = self.overflowing_pow(exp);
2987 a
2988 }
2989
2990 /// Calculates `self` + `rhs`.
2991 ///
2992 /// Returns a tuple of the addition along with a boolean indicating
2993 /// whether an arithmetic overflow would occur. If an overflow would
2994 /// have occurred then the wrapped value is returned.
2995 ///
2996 /// # Examples
2997 ///
2998 /// ```
2999 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_add(2), (7, false));")]
3000 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.overflowing_add(1), (0, true));")]
3001 /// ```
3002 #[stable(feature = "wrapping", since = "1.7.0")]
3003 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3004 #[must_use = "this returns the result of the operation, \
3005 without modifying the original"]
3006 #[inline(always)]
3007 pub const fn overflowing_add(self, rhs: Self) -> (Self, bool) {
3008 let (a, b) = intrinsics::add_with_overflow(self as $ActualT, rhs as $ActualT);
3009 (a as Self, b)
3010 }
3011
3012 /// Calculates `self` + `rhs` + `carry` and returns a tuple containing
3013 /// the sum and the output carry (in that order).
3014 ///
3015 /// Performs "ternary addition" of two integer operands and a carry-in
3016 /// bit, and returns an output integer and a carry-out bit. This allows
3017 /// chaining together multiple additions to create a wider addition, and
3018 /// can be useful for bignum addition.
3019 ///
3020 #[doc = concat!("This can be thought of as a ", stringify!($BITS), "-bit \"full adder\", in the electronics sense.")]
3021 ///
3022 /// If the input carry is false, this method is equivalent to
3023 /// [`overflowing_add`](Self::overflowing_add), and the output carry is
3024 /// equal to the overflow flag. Note that although carry and overflow
3025 /// flags are similar for unsigned integers, they are different for
3026 /// signed integers.
3027 ///
3028 /// # Examples
3029 ///
3030 /// ```
3031 #[doc = concat!("// 3 MAX (a = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
3032 #[doc = concat!("// + 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
3033 /// // ---------
3034 #[doc = concat!("// 9 6 (sum = 9 × 2^", stringify!($BITS), " + 6)")]
3035 ///
3036 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (3, ", stringify!($SelfT), "::MAX);")]
3037 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
3038 /// let carry0 = false;
3039 ///
3040 /// let (sum0, carry1) = a0.carrying_add(b0, carry0);
3041 /// assert_eq!(carry1, true);
3042 /// let (sum1, carry2) = a1.carrying_add(b1, carry1);
3043 /// assert_eq!(carry2, false);
3044 ///
3045 /// assert_eq!((sum1, sum0), (9, 6));
3046 /// ```
3047 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3048 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3049 #[must_use = "this returns the result of the operation, \
3050 without modifying the original"]
3051 #[inline]
3052 pub const fn carrying_add(self, rhs: Self, carry: bool) -> (Self, bool) {
3053 // note: longer-term this should be done via an intrinsic, but this has been shown
3054 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3055 let (a, c1) = self.overflowing_add(rhs);
3056 let (b, c2) = a.overflowing_add(carry as $SelfT);
3057 // Ideally LLVM would know this is disjoint without us telling them,
3058 // but it doesn't <https://github.com/llvm/llvm-project/issues/118162>
3059 // SAFETY: Only one of `c1` and `c2` can be set.
3060 // For c1 to be set we need to have overflowed, but if we did then
3061 // `a` is at most `MAX-1`, which means that `c2` cannot possibly
3062 // overflow because it's adding at most `1` (since it came from `bool`)
3063 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3064 }
3065
3066 /// Calculates `self` + `rhs` with a signed `rhs`.
3067 ///
3068 /// Returns a tuple of the addition along with a boolean indicating
3069 /// whether an arithmetic overflow would occur. If an overflow would
3070 /// have occurred then the wrapped value is returned.
3071 ///
3072 /// # Examples
3073 ///
3074 /// ```
3075 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(2), (3, false));")]
3076 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_add_signed(-2), (", stringify!($SelfT), "::MAX, true));")]
3077 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_add_signed(4), (1, true));")]
3078 /// ```
3079 #[stable(feature = "mixed_integer_ops", since = "1.66.0")]
3080 #[rustc_const_stable(feature = "mixed_integer_ops", since = "1.66.0")]
3081 #[must_use = "this returns the result of the operation, \
3082 without modifying the original"]
3083 #[inline]
3084 pub const fn overflowing_add_signed(self, rhs: $SignedT) -> (Self, bool) {
3085 let (res, overflowed) = self.overflowing_add(rhs as Self);
3086 (res, overflowed ^ (rhs < 0))
3087 }
3088
3089 /// Calculates `self` - `rhs`.
3090 ///
3091 /// Returns a tuple of the subtraction along with a boolean indicating
3092 /// whether an arithmetic overflow would occur. If an overflow would
3093 /// have occurred then the wrapped value is returned.
3094 ///
3095 /// # Examples
3096 ///
3097 /// ```
3098 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_sub(2), (3, false));")]
3099 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_sub(1), (", stringify!($SelfT), "::MAX, true));")]
3100 /// ```
3101 #[stable(feature = "wrapping", since = "1.7.0")]
3102 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3103 #[must_use = "this returns the result of the operation, \
3104 without modifying the original"]
3105 #[inline(always)]
3106 pub const fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
3107 let (a, b) = intrinsics::sub_with_overflow(self as $ActualT, rhs as $ActualT);
3108 (a as Self, b)
3109 }
3110
3111 /// Calculates `self` − `rhs` − `borrow` and returns a tuple
3112 /// containing the difference and the output borrow.
3113 ///
3114 /// Performs "ternary subtraction" by subtracting both an integer
3115 /// operand and a borrow-in bit from `self`, and returns an output
3116 /// integer and a borrow-out bit. This allows chaining together multiple
3117 /// subtractions to create a wider subtraction, and can be useful for
3118 /// bignum subtraction.
3119 ///
3120 /// # Examples
3121 ///
3122 /// ```
3123 #[doc = concat!("// 9 6 (a = 9 × 2^", stringify!($BITS), " + 6)")]
3124 #[doc = concat!("// - 5 7 (b = 5 × 2^", stringify!($BITS), " + 7)")]
3125 /// // ---------
3126 #[doc = concat!("// 3 MAX (diff = 3 × 2^", stringify!($BITS), " + 2^", stringify!($BITS), " - 1)")]
3127 ///
3128 #[doc = concat!("let (a1, a0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (9, 6);")]
3129 #[doc = concat!("let (b1, b0): (", stringify!($SelfT), ", ", stringify!($SelfT), ") = (5, 7);")]
3130 /// let borrow0 = false;
3131 ///
3132 /// let (diff0, borrow1) = a0.borrowing_sub(b0, borrow0);
3133 /// assert_eq!(borrow1, true);
3134 /// let (diff1, borrow2) = a1.borrowing_sub(b1, borrow1);
3135 /// assert_eq!(borrow2, false);
3136 ///
3137 #[doc = concat!("assert_eq!((diff1, diff0), (3, ", stringify!($SelfT), "::MAX));")]
3138 /// ```
3139 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3140 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3141 #[must_use = "this returns the result of the operation, \
3142 without modifying the original"]
3143 #[inline]
3144 pub const fn borrowing_sub(self, rhs: Self, borrow: bool) -> (Self, bool) {
3145 // note: longer-term this should be done via an intrinsic, but this has been shown
3146 // to generate optimal code for now, and LLVM doesn't have an equivalent intrinsic
3147 let (a, c1) = self.overflowing_sub(rhs);
3148 let (b, c2) = a.overflowing_sub(borrow as $SelfT);
3149 // SAFETY: Only one of `c1` and `c2` can be set.
3150 // For c1 to be set we need to have underflowed, but if we did then
3151 // `a` is nonzero, which means that `c2` cannot possibly
3152 // underflow because it's subtracting at most `1` (since it came from `bool`)
3153 (b, unsafe { intrinsics::disjoint_bitor(c1, c2) })
3154 }
3155
3156 /// Calculates `self` - `rhs` with a signed `rhs`
3157 ///
3158 /// Returns a tuple of the subtraction along with a boolean indicating
3159 /// whether an arithmetic overflow would occur. If an overflow would
3160 /// have occurred then the wrapped value is returned.
3161 ///
3162 /// # Examples
3163 ///
3164 /// ```
3165 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(2), (", stringify!($SelfT), "::MAX, true));")]
3166 #[doc = concat!("assert_eq!(1", stringify!($SelfT), ".overflowing_sub_signed(-2), (3, false));")]
3167 #[doc = concat!("assert_eq!((", stringify!($SelfT), "::MAX - 2).overflowing_sub_signed(-4), (1, true));")]
3168 /// ```
3169 #[stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3170 #[rustc_const_stable(feature = "mixed_integer_ops_unsigned_sub", since = "1.90.0")]
3171 #[must_use = "this returns the result of the operation, \
3172 without modifying the original"]
3173 #[inline]
3174 pub const fn overflowing_sub_signed(self, rhs: $SignedT) -> (Self, bool) {
3175 let (res, overflow) = self.overflowing_sub(rhs as Self);
3176
3177 (res, overflow ^ (rhs < 0))
3178 }
3179
3180 /// Computes the absolute difference between `self` and `other`.
3181 ///
3182 /// # Examples
3183 ///
3184 /// ```
3185 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(80), 20", stringify!($SelfT), ");")]
3186 #[doc = concat!("assert_eq!(100", stringify!($SelfT), ".abs_diff(110), 10", stringify!($SelfT), ");")]
3187 /// ```
3188 #[stable(feature = "int_abs_diff", since = "1.60.0")]
3189 #[rustc_const_stable(feature = "int_abs_diff", since = "1.60.0")]
3190 #[must_use = "this returns the result of the operation, \
3191 without modifying the original"]
3192 #[inline]
3193 pub const fn abs_diff(self, other: Self) -> Self {
3194 if size_of::<Self>() == 1 {
3195 // Trick LLVM into generating the psadbw instruction when SSE2
3196 // is available and this function is autovectorized for u8's.
3197 (self as i32).wrapping_sub(other as i32).unsigned_abs() as Self
3198 } else {
3199 if self < other {
3200 other - self
3201 } else {
3202 self - other
3203 }
3204 }
3205 }
3206
3207 /// Calculates the multiplication of `self` and `rhs`.
3208 ///
3209 /// Returns a tuple of the multiplication along with a boolean
3210 /// indicating whether an arithmetic overflow would occur. If an
3211 /// overflow would have occurred then the wrapped value is returned.
3212 ///
3213 /// If you want the *value* of the overflow, rather than just *whether*
3214 /// an overflow occurred, see [`Self::carrying_mul`].
3215 ///
3216 /// # Examples
3217 ///
3218 /// Please note that this example is shared among integer types, which is why `u32` is used.
3219 ///
3220 /// ```
3221 /// assert_eq!(5u32.overflowing_mul(2), (10, false));
3222 /// assert_eq!(1_000_000_000u32.overflowing_mul(10), (1410065408, true));
3223 /// ```
3224 #[stable(feature = "wrapping", since = "1.7.0")]
3225 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3226 #[must_use = "this returns the result of the operation, \
3227 without modifying the original"]
3228 #[inline(always)]
3229 pub const fn overflowing_mul(self, rhs: Self) -> (Self, bool) {
3230 let (a, b) = intrinsics::mul_with_overflow(self as $ActualT, rhs as $ActualT);
3231 (a as Self, b)
3232 }
3233
3234 /// Calculates the "full multiplication" `self * rhs + carry`
3235 /// without the possibility to overflow.
3236 ///
3237 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3238 /// of the result as two separate values, in that order.
3239 ///
3240 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3241 /// additional amount of overflow. This allows for chaining together multiple
3242 /// multiplications to create "big integers" which represent larger values.
3243 ///
3244 /// If you also need to add a value, then use [`Self::carrying_mul_add`].
3245 ///
3246 /// # Examples
3247 ///
3248 /// Please note that this example is shared among integer types, which is why `u32` is used.
3249 ///
3250 /// ```
3251 /// assert_eq!(5u32.carrying_mul(2, 0), (10, 0));
3252 /// assert_eq!(5u32.carrying_mul(2, 10), (20, 0));
3253 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 0), (1410065408, 2));
3254 /// assert_eq!(1_000_000_000u32.carrying_mul(10, 10), (1410065418, 2));
3255 #[doc = concat!("assert_eq!(",
3256 stringify!($SelfT), "::MAX.carrying_mul(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3257 "(0, ", stringify!($SelfT), "::MAX));"
3258 )]
3259 /// ```
3260 ///
3261 /// This is the core operation needed for scalar multiplication when
3262 /// implementing it for wider-than-native types.
3263 ///
3264 /// ```
3265 /// fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
3266 /// let mut carry = 0;
3267 /// for d in little_endian_digits.iter_mut() {
3268 /// (*d, carry) = d.carrying_mul(multiplicand, carry);
3269 /// }
3270 /// if carry != 0 {
3271 /// little_endian_digits.push(carry);
3272 /// }
3273 /// }
3274 ///
3275 /// let mut v = vec![10, 20];
3276 /// scalar_mul_eq(&mut v, 3);
3277 /// assert_eq!(v, [30, 60]);
3278 ///
3279 /// assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
3280 /// let mut v = vec![0x4321, 0x8765];
3281 /// scalar_mul_eq(&mut v, 0xFEED);
3282 /// assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);
3283 /// ```
3284 ///
3285 /// If `carry` is zero, this is similar to [`overflowing_mul`](Self::overflowing_mul),
3286 /// except that it gives the value of the overflow instead of just whether one happened:
3287 ///
3288 /// ```
3289 /// # #![allow(unused_features)]
3290 /// #![feature(const_unsigned_bigint_helpers)]
3291 /// let r = u8::carrying_mul(7, 13, 0);
3292 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(7, 13));
3293 /// let r = u8::carrying_mul(13, 42, 0);
3294 /// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(13, 42));
3295 /// ```
3296 ///
3297 /// The value of the first field in the returned tuple matches what you'd get
3298 /// by combining the [`wrapping_mul`](Self::wrapping_mul) and
3299 /// [`wrapping_add`](Self::wrapping_add) methods:
3300 ///
3301 /// ```
3302 /// # #![allow(unused_features)]
3303 /// #![feature(const_unsigned_bigint_helpers)]
3304 /// assert_eq!(
3305 /// 789_u16.carrying_mul(456, 123).0,
3306 /// 789_u16.wrapping_mul(456).wrapping_add(123),
3307 /// );
3308 /// ```
3309 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3310 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3311 #[must_use = "this returns the result of the operation, \
3312 without modifying the original"]
3313 #[inline]
3314 pub const fn carrying_mul(self, rhs: Self, carry: Self) -> (Self, Self) {
3315 Self::carrying_mul_add(self, rhs, carry, 0)
3316 }
3317
3318 /// Calculates the "full multiplication" `self * rhs + carry + add`.
3319 ///
3320 /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
3321 /// of the result as two separate values, in that order.
3322 ///
3323 /// This cannot overflow, as the double-width result has exactly enough
3324 /// space for the largest possible result. This is equivalent to how, in
3325 /// decimal, 9 × 9 + 9 + 9 = 81 + 18 = 99 = 9×10⁰ + 9×10¹ = 10² - 1.
3326 ///
3327 /// Performs "long multiplication" which takes in an extra amount to add, and may return an
3328 /// additional amount of overflow. This allows for chaining together multiple
3329 /// multiplications to create "big integers" which represent larger values.
3330 ///
3331 /// If you don't need the `add` part, then you can use [`Self::carrying_mul`] instead.
3332 ///
3333 /// # Examples
3334 ///
3335 /// Please note that this example is shared between integer types,
3336 /// which explains why `u32` is used here.
3337 ///
3338 /// ```
3339 /// assert_eq!(5u32.carrying_mul_add(2, 0, 0), (10, 0));
3340 /// assert_eq!(5u32.carrying_mul_add(2, 10, 10), (30, 0));
3341 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 0, 0), (1410065408, 2));
3342 /// assert_eq!(1_000_000_000u32.carrying_mul_add(10, 10, 10), (1410065428, 2));
3343 #[doc = concat!("assert_eq!(",
3344 stringify!($SelfT), "::MAX.carrying_mul_add(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
3345 "(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX));"
3346 )]
3347 /// ```
3348 ///
3349 /// This is the core per-digit operation for "grade school" O(n²) multiplication.
3350 ///
3351 /// Please note that this example is shared between integer types,
3352 /// using `u8` for simplicity of the demonstration.
3353 ///
3354 /// ```
3355 /// fn quadratic_mul<const N: usize>(a: [u8; N], b: [u8; N]) -> [u8; N] {
3356 /// let mut out = [0; N];
3357 /// for j in 0..N {
3358 /// let mut carry = 0;
3359 /// for i in 0..(N - j) {
3360 /// (out[j + i], carry) = u8::carrying_mul_add(a[i], b[j], out[j + i], carry);
3361 /// }
3362 /// }
3363 /// out
3364 /// }
3365 ///
3366 /// // -1 * -1 == 1
3367 /// assert_eq!(quadratic_mul([0xFF; 3], [0xFF; 3]), [1, 0, 0]);
3368 ///
3369 /// assert_eq!(u32::wrapping_mul(0x9e3779b9, 0x7f4a7c15), 0xcffc982d);
3370 /// assert_eq!(
3371 /// quadratic_mul(u32::to_le_bytes(0x9e3779b9), u32::to_le_bytes(0x7f4a7c15)),
3372 /// u32::to_le_bytes(0xcffc982d)
3373 /// );
3374 /// ```
3375 #[stable(feature = "unsigned_bigint_helpers", since = "1.91.0")]
3376 #[rustc_const_unstable(feature = "const_unsigned_bigint_helpers", issue = "152015")]
3377 #[must_use = "this returns the result of the operation, \
3378 without modifying the original"]
3379 #[inline]
3380 pub const fn carrying_mul_add(self, rhs: Self, carry: Self, add: Self) -> (Self, Self) {
3381 intrinsics::carrying_mul_add(self, rhs, carry, add)
3382 }
3383
3384 /// Calculates the divisor when `self` is divided by `rhs`.
3385 ///
3386 /// Returns a tuple of the divisor along with a boolean indicating
3387 /// whether an arithmetic overflow would occur. Note that for unsigned
3388 /// integers overflow never occurs, so the second value is always
3389 /// `false`.
3390 ///
3391 /// # Panics
3392 ///
3393 /// This function will panic if `rhs` is zero.
3394 ///
3395 /// # Examples
3396 ///
3397 /// ```
3398 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div(2), (2, false));")]
3399 /// ```
3400 #[inline(always)]
3401 #[stable(feature = "wrapping", since = "1.7.0")]
3402 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3403 #[must_use = "this returns the result of the operation, \
3404 without modifying the original"]
3405 #[track_caller]
3406 pub const fn overflowing_div(self, rhs: Self) -> (Self, bool) {
3407 (self / rhs, false)
3408 }
3409
3410 /// Calculates the quotient of Euclidean division `self.div_euclid(rhs)`.
3411 ///
3412 /// Returns a tuple of the divisor along with a boolean indicating
3413 /// whether an arithmetic overflow would occur. Note that for unsigned
3414 /// integers overflow never occurs, so the second value is always
3415 /// `false`.
3416 /// Since, for the positive integers, all common
3417 /// definitions of division are equal, this
3418 /// is exactly equal to `self.overflowing_div(rhs)`.
3419 ///
3420 /// # Panics
3421 ///
3422 /// This function will panic if `rhs` is zero.
3423 ///
3424 /// # Examples
3425 ///
3426 /// ```
3427 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_div_euclid(2), (2, false));")]
3428 /// ```
3429 #[inline(always)]
3430 #[stable(feature = "euclidean_division", since = "1.38.0")]
3431 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3432 #[must_use = "this returns the result of the operation, \
3433 without modifying the original"]
3434 #[track_caller]
3435 pub const fn overflowing_div_euclid(self, rhs: Self) -> (Self, bool) {
3436 (self / rhs, false)
3437 }
3438
3439 /// Calculates the remainder when `self` is divided by `rhs`.
3440 ///
3441 /// Returns a tuple of the remainder after dividing along with a boolean
3442 /// indicating whether an arithmetic overflow would occur. Note that for
3443 /// unsigned integers overflow never occurs, so the second value is
3444 /// always `false`.
3445 ///
3446 /// # Panics
3447 ///
3448 /// This function will panic if `rhs` is zero.
3449 ///
3450 /// # Examples
3451 ///
3452 /// ```
3453 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem(2), (1, false));")]
3454 /// ```
3455 #[inline(always)]
3456 #[stable(feature = "wrapping", since = "1.7.0")]
3457 #[rustc_const_stable(feature = "const_overflowing_int_methods", since = "1.52.0")]
3458 #[must_use = "this returns the result of the operation, \
3459 without modifying the original"]
3460 #[track_caller]
3461 pub const fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
3462 (self % rhs, false)
3463 }
3464
3465 /// Calculates the remainder `self.rem_euclid(rhs)` as if by Euclidean division.
3466 ///
3467 /// Returns a tuple of the modulo after dividing along with a boolean
3468 /// indicating whether an arithmetic overflow would occur. Note that for
3469 /// unsigned integers overflow never occurs, so the second value is
3470 /// always `false`.
3471 /// Since, for the positive integers, all common
3472 /// definitions of division are equal, this operation
3473 /// is exactly equal to `self.overflowing_rem(rhs)`.
3474 ///
3475 /// # Panics
3476 ///
3477 /// This function will panic if `rhs` is zero.
3478 ///
3479 /// # Examples
3480 ///
3481 /// ```
3482 #[doc = concat!("assert_eq!(5", stringify!($SelfT), ".overflowing_rem_euclid(2), (1, false));")]
3483 /// ```
3484 #[inline(always)]
3485 #[stable(feature = "euclidean_division", since = "1.38.0")]
3486 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3487 #[must_use = "this returns the result of the operation, \
3488 without modifying the original"]
3489 #[track_caller]
3490 pub const fn overflowing_rem_euclid(self, rhs: Self) -> (Self, bool) {
3491 (self % rhs, false)
3492 }
3493
3494 /// Negates self in an overflowing fashion.
3495 ///
3496 /// Returns `!self + 1` using wrapping operations to return the value
3497 /// that represents the negation of this unsigned value. Note that for
3498 /// positive unsigned values overflow always occurs, but negating 0 does
3499 /// not overflow.
3500 ///
3501 /// # Examples
3502 ///
3503 /// ```
3504 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".overflowing_neg(), (0, false));")]
3505 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".overflowing_neg(), (-2i32 as ", stringify!($SelfT), ", true));")]
3506 /// ```
3507 #[inline(always)]
3508 #[stable(feature = "wrapping", since = "1.7.0")]
3509 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3510 #[must_use = "this returns the result of the operation, \
3511 without modifying the original"]
3512 pub const fn overflowing_neg(self) -> (Self, bool) {
3513 ((!self).wrapping_add(1), self != 0)
3514 }
3515
3516 /// Shifts self left by `rhs` bits.
3517 ///
3518 /// Returns a tuple of the shifted version of self along with a boolean
3519 /// indicating whether the shift value was larger than or equal to the
3520 /// number of bits. If the shift value is too large, then value is
3521 /// masked (N-1) where N is the number of bits, and this value is then
3522 /// used to perform the shift.
3523 ///
3524 /// # Examples
3525 ///
3526 /// ```
3527 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(4), (0x10, false));")]
3528 #[doc = concat!("assert_eq!(0x1", stringify!($SelfT), ".overflowing_shl(132), (0x10, true));")]
3529 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shl(", stringify!($BITS_MINUS_ONE), "), (0, false));")]
3530 /// ```
3531 #[stable(feature = "wrapping", since = "1.7.0")]
3532 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3533 #[must_use = "this returns the result of the operation, \
3534 without modifying the original"]
3535 #[inline(always)]
3536 pub const fn overflowing_shl(self, rhs: u32) -> (Self, bool) {
3537 (self.wrapping_shl(rhs), rhs >= Self::BITS)
3538 }
3539
3540 /// Shifts self right by `rhs` bits.
3541 ///
3542 /// Returns a tuple of the shifted version of self along with a boolean
3543 /// indicating whether the shift value was larger than or equal to the
3544 /// number of bits. If the shift value is too large, then value is
3545 /// masked (N-1) where N is the number of bits, and this value is then
3546 /// used to perform the shift.
3547 ///
3548 /// # Examples
3549 ///
3550 /// ```
3551 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(4), (0x1, false));")]
3552 #[doc = concat!("assert_eq!(0x10", stringify!($SelfT), ".overflowing_shr(132), (0x1, true));")]
3553 /// ```
3554 #[stable(feature = "wrapping", since = "1.7.0")]
3555 #[rustc_const_stable(feature = "const_wrapping_math", since = "1.32.0")]
3556 #[must_use = "this returns the result of the operation, \
3557 without modifying the original"]
3558 #[inline(always)]
3559 pub const fn overflowing_shr(self, rhs: u32) -> (Self, bool) {
3560 (self.wrapping_shr(rhs), rhs >= Self::BITS)
3561 }
3562
3563 /// Raises self to the power of `exp`, using exponentiation by squaring.
3564 ///
3565 /// Returns a tuple of the exponentiation along with a bool indicating
3566 /// whether an overflow happened.
3567 ///
3568 /// # Examples
3569 ///
3570 /// ```
3571 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".overflowing_pow(5), (243, false));")]
3572 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".overflowing_pow(0), (1, false));")]
3573 /// assert_eq!(3u8.overflowing_pow(6), (217, true));
3574 /// ```
3575 #[stable(feature = "no_panic_pow", since = "1.34.0")]
3576 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3577 #[must_use = "this returns the result of the operation, \
3578 without modifying the original"]
3579 #[inline]
3580 pub const fn overflowing_pow(self, mut exp: u32) -> (Self, bool) {
3581 let mut base = self;
3582 let mut acc: Self = 1;
3583 let mut overflow = false;
3584 let mut tmp_overflow;
3585
3586 if intrinsics::is_val_statically_known(base) && base.is_power_of_two() {
3587 // change of base:
3588 // if base == 2 ** k, then
3589 // (2 ** k) ** n
3590 // == 2 ** (k * n)
3591 // == 1 << (k * n)
3592 let k = base.ilog2();
3593 let Some(shift) = k.checked_mul(exp) else {
3594 return (0, true)
3595 };
3596 return ((1 as Self).unbounded_shl(shift), shift >= Self::BITS)
3597 }
3598
3599 if exp == 0 {
3600 return (1, false);
3601 }
3602
3603 if intrinsics::is_val_statically_known(exp) {
3604 while exp > 1 {
3605 if (exp & 1) == 1 {
3606 (acc, tmp_overflow) = acc.overflowing_mul(base);
3607 overflow |= tmp_overflow;
3608 }
3609 exp /= 2;
3610 (base, tmp_overflow) = base.overflowing_mul(base);
3611 overflow |= tmp_overflow;
3612 }
3613
3614 // since exp!=0, finally the exp must be 1.
3615 // Deal with the final bit of the exponent separately, since
3616 // squaring the base afterwards is not necessary and may cause a
3617 // needless overflow.
3618 (acc, tmp_overflow) = acc.overflowing_mul(base);
3619 overflow |= tmp_overflow;
3620 return (acc, overflow);
3621 }
3622
3623 loop {
3624 if (exp & 1) == 1 {
3625 (acc, tmp_overflow) = acc.overflowing_mul(base);
3626 overflow |= tmp_overflow;
3627 // since exp!=0, finally the exp must be 1.
3628 if exp == 1 {
3629 return (acc, overflow);
3630 }
3631 }
3632 exp /= 2;
3633 (base, tmp_overflow) = base.overflowing_mul(base);
3634 overflow |= tmp_overflow;
3635 }
3636 }
3637
3638 /// Raises self to the power of `exp`, using exponentiation by squaring.
3639 ///
3640 /// # Examples
3641 ///
3642 /// ```
3643 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".pow(5), 32);")]
3644 #[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".pow(0), 1);")]
3645 /// ```
3646 #[stable(feature = "rust1", since = "1.0.0")]
3647 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3648 #[must_use = "this returns the result of the operation, \
3649 without modifying the original"]
3650 #[inline]
3651 #[rustc_inherit_overflow_checks]
3652 pub const fn pow(self, exp: u32) -> Self {
3653 if intrinsics::overflow_checks() {
3654 self.strict_pow(exp)
3655 } else {
3656 self.wrapping_pow(exp)
3657 }
3658 }
3659
3660 /// Returns the square root of the number, rounded down.
3661 ///
3662 /// # Examples
3663 ///
3664 /// ```
3665 #[doc = concat!("assert_eq!(10", stringify!($SelfT), ".isqrt(), 3);")]
3666 /// ```
3667 #[stable(feature = "isqrt", since = "1.84.0")]
3668 #[rustc_const_stable(feature = "isqrt", since = "1.84.0")]
3669 #[must_use = "this returns the result of the operation, \
3670 without modifying the original"]
3671 #[inline]
3672 pub const fn isqrt(self) -> Self {
3673 let result = imp::int_sqrt::$ActualT(self as $ActualT) as Self;
3674
3675 // Inform the optimizer what the range of outputs is. If testing
3676 // `core` crashes with no panic message and a `num::int_sqrt::u*`
3677 // test failed, it's because your edits caused these assertions or
3678 // the assertions in `fn isqrt` of `nonzero.rs` to become false.
3679 //
3680 // SAFETY: Integer square root is a monotonically nondecreasing
3681 // function, which means that increasing the input will never
3682 // cause the output to decrease. Thus, since the input for unsigned
3683 // integers is bounded by `[0, <$ActualT>::MAX]`, sqrt(n) will be
3684 // bounded by `[sqrt(0), sqrt(<$ActualT>::MAX)]` and bounding the
3685 // input by `[1, <$ActualT>::MAX]` bounds sqrt(n) by
3686 // `[sqrt(1), sqrt(<$ActualT>::MAX)]`.
3687 unsafe {
3688 const MAX_RESULT: $SelfT = imp::int_sqrt::$ActualT(<$ActualT>::MAX) as $SelfT;
3689 crate::hint::assert_unchecked(result <= MAX_RESULT)
3690 }
3691
3692 if self >= 1 {
3693 // SAFETY: The above statements about monotonicity also apply here.
3694 // Since the input in this branch is bounded by `[1, <$ActualT>::MAX]`,
3695 // sqrt(n) is bounded by `[sqrt(1), sqrt(<$ActualT>::MAX)]`, and
3696 // `sqrt(1) == 1`.
3697 unsafe { crate::hint::assert_unchecked(result >= 1) }
3698 }
3699
3700 // SAFETY: the isqrt implementation returns the square root and rounds down,
3701 // meaning `result * result <= self`. This implies `result <= self`.
3702 // The compiler needs both to optimize for both.
3703 // `result * result <= self` implies the multiplication will not overflow.
3704 unsafe {
3705 crate::hint::assert_unchecked(result.unchecked_mul(result) <= self);
3706 crate::hint::assert_unchecked(result <= self);
3707 }
3708
3709 result
3710 }
3711
3712 /// Performs Euclidean division.
3713 ///
3714 /// Since, for the positive integers, all common
3715 /// definitions of division are equal, this
3716 /// is exactly equal to `self / rhs`.
3717 ///
3718 /// # Panics
3719 ///
3720 /// This function will panic if `rhs` is zero.
3721 ///
3722 /// # Examples
3723 ///
3724 /// ```
3725 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".div_euclid(4), 1); // or any other integer type")]
3726 /// ```
3727 #[stable(feature = "euclidean_division", since = "1.38.0")]
3728 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3729 #[must_use = "this returns the result of the operation, \
3730 without modifying the original"]
3731 #[inline(always)]
3732 #[track_caller]
3733 pub const fn div_euclid(self, rhs: Self) -> Self {
3734 self / rhs
3735 }
3736
3737 /// Calculates the least remainder of `self` when divided by
3738 /// `rhs`.
3739 ///
3740 /// Since, for the positive integers, all common
3741 /// definitions of division are equal, this
3742 /// is exactly equal to `self % rhs`.
3743 ///
3744 /// # Panics
3745 ///
3746 /// This function will panic if `rhs` is zero.
3747 ///
3748 /// # Examples
3749 ///
3750 /// ```
3751 #[doc = concat!("assert_eq!(7", stringify!($SelfT), ".rem_euclid(4), 3); // or any other integer type")]
3752 /// ```
3753 #[doc(alias = "modulo", alias = "mod")]
3754 #[stable(feature = "euclidean_division", since = "1.38.0")]
3755 #[rustc_const_stable(feature = "const_euclidean_int_methods", since = "1.52.0")]
3756 #[must_use = "this returns the result of the operation, \
3757 without modifying the original"]
3758 #[inline(always)]
3759 #[track_caller]
3760 pub const fn rem_euclid(self, rhs: Self) -> Self {
3761 self % rhs
3762 }
3763
3764 /// Calculates the quotient of `self` and `rhs`, rounding the result towards negative infinity.
3765 ///
3766 /// This is the same as performing `self / rhs` for all unsigned integers.
3767 ///
3768 /// # Panics
3769 ///
3770 /// This function will panic if `rhs` is zero.
3771 ///
3772 /// # Examples
3773 ///
3774 /// ```
3775 /// #![feature(int_roundings)]
3776 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_floor(4), 1);")]
3777 /// ```
3778 #[unstable(feature = "int_roundings", issue = "88581")]
3779 #[must_use = "this returns the result of the operation, \
3780 without modifying the original"]
3781 #[inline(always)]
3782 #[track_caller]
3783 pub const fn div_floor(self, rhs: Self) -> Self {
3784 self / rhs
3785 }
3786
3787 /// Calculates the quotient of `self` and `rhs`, rounding the result towards positive infinity.
3788 ///
3789 /// # Panics
3790 ///
3791 /// This function will panic if `rhs` is zero.
3792 ///
3793 /// # Examples
3794 ///
3795 /// ```
3796 #[doc = concat!("assert_eq!(7_", stringify!($SelfT), ".div_ceil(4), 2);")]
3797 /// ```
3798 #[stable(feature = "int_roundings1", since = "1.73.0")]
3799 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3800 #[must_use = "this returns the result of the operation, \
3801 without modifying the original"]
3802 #[inline]
3803 #[track_caller]
3804 pub const fn div_ceil(self, rhs: Self) -> Self {
3805 let d = self / rhs;
3806 let r = self % rhs;
3807 if r > 0 {
3808 d + 1
3809 } else {
3810 d
3811 }
3812 }
3813
3814 /// Calculates the smallest value greater than or equal to `self` that
3815 /// is a multiple of `rhs`.
3816 ///
3817 /// # Panics
3818 ///
3819 /// This function will panic if `rhs` is zero.
3820 ///
3821 /// ## Overflow behavior
3822 ///
3823 /// On overflow, this function will panic if overflow checks are enabled (default in debug
3824 /// mode) and wrap if overflow checks are disabled (default in release mode).
3825 ///
3826 /// # Examples
3827 ///
3828 /// ```
3829 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".next_multiple_of(8), 16);")]
3830 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".next_multiple_of(8), 24);")]
3831 /// ```
3832 #[stable(feature = "int_roundings1", since = "1.73.0")]
3833 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3834 #[must_use = "this returns the result of the operation, \
3835 without modifying the original"]
3836 #[inline]
3837 #[rustc_inherit_overflow_checks]
3838 pub const fn next_multiple_of(self, rhs: Self) -> Self {
3839 match self % rhs {
3840 0 => self,
3841 r => self + (rhs - r)
3842 }
3843 }
3844
3845 /// Calculates the smallest value greater than or equal to `self` that
3846 /// is a multiple of `rhs`. Returns `None` if `rhs` is zero or the
3847 /// operation would result in overflow.
3848 ///
3849 /// # Examples
3850 ///
3851 /// ```
3852 #[doc = concat!("assert_eq!(16_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(16));")]
3853 #[doc = concat!("assert_eq!(23_", stringify!($SelfT), ".checked_next_multiple_of(8), Some(24));")]
3854 #[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".checked_next_multiple_of(0), None);")]
3855 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_multiple_of(2), None);")]
3856 /// ```
3857 #[stable(feature = "int_roundings1", since = "1.73.0")]
3858 #[rustc_const_stable(feature = "int_roundings1", since = "1.73.0")]
3859 #[must_use = "this returns the result of the operation, \
3860 without modifying the original"]
3861 #[inline]
3862 pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self> {
3863 match try_opt!(self.checked_rem(rhs)) {
3864 0 => Some(self),
3865 // rhs - r cannot overflow because r is smaller than rhs
3866 r => self.checked_add(rhs - r)
3867 }
3868 }
3869
3870 /// Returns `true` if `self` is an integer multiple of `rhs`, and false otherwise.
3871 ///
3872 /// This function is equivalent to `self % rhs == 0`, except that it will not panic
3873 /// for `rhs == 0`. Instead, `0.is_multiple_of(0) == true`, and for any non-zero `n`,
3874 /// `n.is_multiple_of(0) == false`.
3875 ///
3876 /// # Examples
3877 ///
3878 /// ```
3879 #[doc = concat!("assert!(6_", stringify!($SelfT), ".is_multiple_of(2));")]
3880 #[doc = concat!("assert!(!5_", stringify!($SelfT), ".is_multiple_of(2));")]
3881 ///
3882 #[doc = concat!("assert!(0_", stringify!($SelfT), ".is_multiple_of(0));")]
3883 #[doc = concat!("assert!(!6_", stringify!($SelfT), ".is_multiple_of(0));")]
3884 /// ```
3885 #[stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3886 #[rustc_const_stable(feature = "unsigned_is_multiple_of", since = "1.87.0")]
3887 #[must_use]
3888 #[inline]
3889 pub const fn is_multiple_of(self, rhs: Self) -> bool {
3890 match rhs {
3891 0 => self == 0,
3892 _ => self % rhs == 0,
3893 }
3894 }
3895
3896 /// Returns `true` if and only if `self == 2^k` for some unsigned integer `k`.
3897 ///
3898 /// # Examples
3899 ///
3900 /// ```
3901 #[doc = concat!("assert!(16", stringify!($SelfT), ".is_power_of_two());")]
3902 #[doc = concat!("assert!(!10", stringify!($SelfT), ".is_power_of_two());")]
3903 /// ```
3904 #[must_use]
3905 #[stable(feature = "rust1", since = "1.0.0")]
3906 #[rustc_const_stable(feature = "const_is_power_of_two", since = "1.32.0")]
3907 #[inline(always)]
3908 pub const fn is_power_of_two(self) -> bool {
3909 self.count_ones() == 1
3910 }
3911
3912 /// Returns the smallest power of two greater than or equal to `self`.
3913 ///
3914 /// When return value overflows (i.e., `self > (1 << (N-1))` for type
3915 /// `uN`), it panics in debug mode and the return value is wrapped to 0 in
3916 /// release mode (the only situation in which this method can return 0).
3917 ///
3918 /// # Examples
3919 ///
3920 /// ```
3921 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".next_power_of_two(), 2);")]
3922 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".next_power_of_two(), 4);")]
3923 #[doc = concat!("assert_eq!(0", stringify!($SelfT), ".next_power_of_two(), 1);")]
3924 /// ```
3925 #[stable(feature = "rust1", since = "1.0.0")]
3926 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3927 #[must_use = "this returns the result of the operation, \
3928 without modifying the original"]
3929 #[inline]
3930 #[rustc_inherit_overflow_checks]
3931 pub const fn next_power_of_two(self) -> Self {
3932 if let Some(npot) = self.checked_next_power_of_two() {
3933 npot
3934 } else {
3935 #[expect(arithmetic_overflow)]
3936 {
3937 // Zero but in a way that panics in debug
3938 Self::MAX + 1
3939 }
3940 }
3941 }
3942
3943 /// Returns the smallest power of two greater than or equal to `self`. If
3944 /// the next power of two is greater than the type's maximum value,
3945 /// `None` is returned, otherwise the power of two is wrapped in `Some`.
3946 ///
3947 /// # Examples
3948 ///
3949 /// ```
3950 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_next_power_of_two(), Some(2));")]
3951 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".checked_next_power_of_two(), Some(4));")]
3952 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_next_power_of_two(), None);")]
3953 /// ```
3954 #[inline]
3955 #[stable(feature = "rust1", since = "1.0.0")]
3956 #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
3957 #[must_use = "this returns the result of the operation, \
3958 without modifying the original"]
3959 pub const fn checked_next_power_of_two(self) -> Option<Self> {
3960 let m1 = self.saturating_sub(1);
3961 if m1.cast_signed() >= 0 {
3962 let exp = m1.bit_width();
3963 Some(1 << exp)
3964 } else {
3965 None
3966 }
3967 }
3968
3969 /// Returns the smallest power of two greater than or equal to `n`. If
3970 /// the next power of two is greater than the type's maximum value,
3971 /// the return value is wrapped to `0`.
3972 ///
3973 /// # Examples
3974 ///
3975 /// ```
3976 /// #![feature(wrapping_next_power_of_two)]
3977 ///
3978 #[doc = concat!("assert_eq!(2", stringify!($SelfT), ".wrapping_next_power_of_two(), 2);")]
3979 #[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_next_power_of_two(), 4);")]
3980 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.wrapping_next_power_of_two(), 0);")]
3981 /// ```
3982 #[inline]
3983 #[unstable(feature = "wrapping_next_power_of_two", issue = "32463",
3984 reason = "needs decision on wrapping behavior")]
3985 #[rustc_const_unstable(feature = "wrapping_next_power_of_two", issue = "32463")]
3986 #[must_use = "this returns the result of the operation, \
3987 without modifying the original"]
3988 pub const fn wrapping_next_power_of_two(self) -> Self {
3989 self.checked_next_power_of_two().unwrap_or(0)
3990 }
3991
3992 /// Returns the memory representation of this integer as a byte array in
3993 /// big-endian (network) byte order.
3994 ///
3995 #[doc = $to_xe_bytes_doc]
3996 ///
3997 /// # Examples
3998 ///
3999 /// ```
4000 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_be_bytes();")]
4001 #[doc = concat!("assert_eq!(bytes, ", $be_bytes, ");")]
4002 /// ```
4003 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4004 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4005 #[must_use = "this returns the result of the operation, \
4006 without modifying the original"]
4007 #[inline]
4008 pub const fn to_be_bytes(self) -> [u8; size_of::<Self>()] {
4009 self.to_be().to_ne_bytes()
4010 }
4011
4012 /// Returns the memory representation of this integer as a byte array in
4013 /// little-endian byte order.
4014 ///
4015 #[doc = $to_xe_bytes_doc]
4016 ///
4017 /// # Examples
4018 ///
4019 /// ```
4020 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_le_bytes();")]
4021 #[doc = concat!("assert_eq!(bytes, ", $le_bytes, ");")]
4022 /// ```
4023 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4024 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4025 #[must_use = "this returns the result of the operation, \
4026 without modifying the original"]
4027 #[inline]
4028 pub const fn to_le_bytes(self) -> [u8; size_of::<Self>()] {
4029 self.to_le().to_ne_bytes()
4030 }
4031
4032 /// Returns the memory representation of this integer as a byte array in
4033 /// native byte order.
4034 ///
4035 /// As the target platform's native endianness is used, portable code
4036 /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate,
4037 /// instead.
4038 ///
4039 #[doc = $to_xe_bytes_doc]
4040 ///
4041 /// [`to_be_bytes`]: Self::to_be_bytes
4042 /// [`to_le_bytes`]: Self::to_le_bytes
4043 ///
4044 /// # Examples
4045 ///
4046 /// ```
4047 #[doc = concat!("let bytes = ", $swap_op, stringify!($SelfT), ".to_ne_bytes();")]
4048 /// assert_eq!(
4049 /// bytes,
4050 /// if cfg!(target_endian = "big") {
4051 #[doc = concat!(" ", $be_bytes)]
4052 /// } else {
4053 #[doc = concat!(" ", $le_bytes)]
4054 /// }
4055 /// );
4056 /// ```
4057 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4058 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4059 #[must_use = "this returns the result of the operation, \
4060 without modifying the original"]
4061 #[allow(unnecessary_transmutes)]
4062 // SAFETY: const sound because integers are plain old datatypes so we can always
4063 // transmute them to arrays of bytes
4064 #[inline]
4065 pub const fn to_ne_bytes(self) -> [u8; size_of::<Self>()] {
4066 // SAFETY: integers are plain old datatypes so we can always transmute them to
4067 // arrays of bytes
4068 unsafe { mem::transmute(self) }
4069 }
4070
4071 /// Creates a native endian integer value from its representation
4072 /// as a byte array in big endian.
4073 ///
4074 #[doc = $from_xe_bytes_doc]
4075 ///
4076 /// # Examples
4077 ///
4078 /// ```
4079 #[doc = concat!("let value = ", stringify!($SelfT), "::from_be_bytes(", $be_bytes, ");")]
4080 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4081 /// ```
4082 ///
4083 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4084 ///
4085 /// ```
4086 #[doc = concat!("fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4087 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4088 /// *input = rest;
4089 #[doc = concat!(" ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())")]
4090 /// }
4091 /// ```
4092 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4093 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4094 #[must_use]
4095 #[inline]
4096 pub const fn from_be_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4097 Self::from_be(Self::from_ne_bytes(bytes))
4098 }
4099
4100 /// Creates a native endian integer value from its representation
4101 /// as a byte array in little endian.
4102 ///
4103 #[doc = $from_xe_bytes_doc]
4104 ///
4105 /// # Examples
4106 ///
4107 /// ```
4108 #[doc = concat!("let value = ", stringify!($SelfT), "::from_le_bytes(", $le_bytes, ");")]
4109 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4110 /// ```
4111 ///
4112 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4113 ///
4114 /// ```
4115 #[doc = concat!("fn read_le_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4116 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4117 /// *input = rest;
4118 #[doc = concat!(" ", stringify!($SelfT), "::from_le_bytes(int_bytes.try_into().unwrap())")]
4119 /// }
4120 /// ```
4121 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4122 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4123 #[must_use]
4124 #[inline]
4125 pub const fn from_le_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4126 Self::from_le(Self::from_ne_bytes(bytes))
4127 }
4128
4129 /// Creates a native endian integer value from its memory representation
4130 /// as a byte array in native endianness.
4131 ///
4132 /// As the target platform's native endianness is used, portable code
4133 /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
4134 /// appropriate instead.
4135 ///
4136 /// [`from_be_bytes`]: Self::from_be_bytes
4137 /// [`from_le_bytes`]: Self::from_le_bytes
4138 ///
4139 #[doc = $from_xe_bytes_doc]
4140 ///
4141 /// # Examples
4142 ///
4143 /// ```
4144 #[doc = concat!("let value = ", stringify!($SelfT), "::from_ne_bytes(if cfg!(target_endian = \"big\") {")]
4145 #[doc = concat!(" ", $be_bytes, "")]
4146 /// } else {
4147 #[doc = concat!(" ", $le_bytes, "")]
4148 /// });
4149 #[doc = concat!("assert_eq!(value, ", $swap_op, ");")]
4150 /// ```
4151 ///
4152 /// When starting from a slice rather than an array, fallible conversion APIs can be used:
4153 ///
4154 /// ```
4155 #[doc = concat!("fn read_ne_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {")]
4156 #[doc = concat!(" let (int_bytes, rest) = input.split_at(size_of::<", stringify!($SelfT), ">());")]
4157 /// *input = rest;
4158 #[doc = concat!(" ", stringify!($SelfT), "::from_ne_bytes(int_bytes.try_into().unwrap())")]
4159 /// }
4160 /// ```
4161 #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
4162 #[rustc_const_stable(feature = "const_int_conversion", since = "1.44.0")]
4163 #[allow(unnecessary_transmutes)]
4164 #[must_use]
4165 // SAFETY: const sound because integers are plain old datatypes so we can always
4166 // transmute to them
4167 #[inline]
4168 pub const fn from_ne_bytes(bytes: [u8; size_of::<Self>()]) -> Self {
4169 // SAFETY: integers are plain old datatypes so we can always transmute to them
4170 unsafe { mem::transmute(bytes) }
4171 }
4172
4173 /// New code should prefer to use
4174 #[doc = concat!("[`", stringify!($SelfT), "::MIN", "`] instead.")]
4175 ///
4176 /// Returns the smallest value that can be represented by this integer type.
4177 #[stable(feature = "rust1", since = "1.0.0")]
4178 #[rustc_promotable]
4179 #[inline(always)]
4180 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4181 #[deprecated(since = "1.99.0", note = "replaced by the `MIN` associated constant on this type")]
4182 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_min_value")]
4183 pub const fn min_value() -> Self { Self::MIN }
4184
4185 /// New code should prefer to use
4186 #[doc = concat!("[`", stringify!($SelfT), "::MAX", "`] instead.")]
4187 ///
4188 /// Returns the largest value that can be represented by this integer type.
4189 #[stable(feature = "rust1", since = "1.0.0")]
4190 #[rustc_promotable]
4191 #[inline(always)]
4192 #[rustc_const_stable(feature = "const_max_value", since = "1.32.0")]
4193 #[deprecated(since = "1.99.0", note = "replaced by the `MAX` associated constant on this type")]
4194 #[rustc_diagnostic_item = concat!(stringify!($SelfT), "_legacy_fn_max_value")]
4195 pub const fn max_value() -> Self { Self::MAX }
4196
4197 /// Truncate an integer to an integer of the same size or smaller, preserving the least
4198 /// significant bits.
4199 ///
4200 /// # Examples
4201 ///
4202 /// ```
4203 /// #![feature(integer_widen_truncate)]
4204 #[doc = concat!("assert_eq!(120u8, 120", stringify!($SelfT), ".truncate());")]
4205 /// assert_eq!(120u8, 376u32.truncate());
4206 /// ```
4207 #[must_use = "this returns the truncated value and does not modify the original"]
4208 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4209 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4210 #[inline]
4211 pub const fn truncate<Target>(self) -> Target
4212 where Self: [const] traits::TruncateTarget<Target>
4213 {
4214 traits::TruncateTarget::internal_truncate(self)
4215 }
4216
4217 /// Truncate an integer to an integer of the same size or smaller, saturating at numeric bounds
4218 /// instead of truncating.
4219 ///
4220 /// # Examples
4221 ///
4222 /// ```
4223 /// #![feature(integer_widen_truncate)]
4224 #[doc = concat!("assert_eq!(120u8, 120", stringify!($SelfT), ".saturating_truncate());")]
4225 /// assert_eq!(255u8, 376u32.saturating_truncate());
4226 /// ```
4227 #[must_use = "this returns the truncated value and does not modify the original"]
4228 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4229 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4230 #[inline]
4231 pub const fn saturating_truncate<Target>(self) -> Target
4232 where Self: [const] traits::TruncateTarget<Target>
4233 {
4234 traits::TruncateTarget::internal_saturating_truncate(self)
4235 }
4236
4237 /// Truncate an integer to an integer of the same size or smaller, returning `None` if the value
4238 /// is outside the bounds of the smaller type.
4239 ///
4240 /// # Examples
4241 ///
4242 /// ```
4243 /// #![feature(integer_widen_truncate)]
4244 #[doc = concat!("assert_eq!(Some(120u8), 120", stringify!($SelfT), ".checked_truncate());")]
4245 /// assert_eq!(None, 376u32.checked_truncate::<u8>());
4246 /// ```
4247 #[must_use = "this returns the truncated value and does not modify the original"]
4248 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4249 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4250 #[inline]
4251 pub const fn checked_truncate<Target>(self) -> Option<Target>
4252 where Self: [const] traits::TruncateTarget<Target>
4253 {
4254 traits::TruncateTarget::internal_checked_truncate(self)
4255 }
4256
4257 /// Widen to an integer of the same size or larger, preserving its value.
4258 ///
4259 /// # Examples
4260 ///
4261 /// ```
4262 /// #![feature(integer_widen_truncate)]
4263 #[doc = concat!("assert_eq!(120u128, 120u8.widen());")]
4264 /// ```
4265 #[must_use = "this returns the widened value and does not modify the original"]
4266 #[unstable(feature = "integer_widen_truncate", issue = "154330")]
4267 #[rustc_const_unstable(feature = "integer_widen_truncate", issue = "154330")]
4268 #[inline]
4269 pub const fn widen<Target>(self) -> Target
4270 where Self: [const] traits::WidenTarget<Target>
4271 {
4272 traits::WidenTarget::internal_widen(self)
4273 }
4274
4275 /// Converts `self` to the target integer type, saturating at the numeric
4276 /// bounds instead of overflowing.
4277 ///
4278 /// # Examples
4279 ///
4280 /// ```
4281 /// #![feature(integer_casts)]
4282 #[doc = concat!("assert_eq!(255u8, ", stringify!($SelfT), "::MAX.saturating_cast());")]
4283 #[doc = concat!("assert_eq!(127i8, ", stringify!($SelfT), "::MAX.saturating_cast());")]
4284 #[doc = concat!("assert_eq!(42i8, 42", stringify!($SelfT), ".saturating_cast());")]
4285 /// ```
4286 #[must_use = "this returns the cast result and does not modify the original"]
4287 #[unstable(feature = "integer_casts", issue = "157388")]
4288 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4289 #[inline(always)]
4290 pub const fn saturating_cast<T: [const] BoundedCastFromInt<Self>>(self) -> T {
4291 T::saturating_cast_from(self)
4292 }
4293
4294 /// Converts `self` to the target integer type, wrapping around at the
4295 /// boundary of the target type.
4296 ///
4297 /// # Examples
4298 ///
4299 /// ```
4300 /// #![feature(integer_casts)]
4301 #[doc = concat!("assert_eq!(255u8, ", stringify!($SelfT), "::MAX.wrapping_cast());")]
4302 #[doc = concat!("assert_eq!(42i8, 42", stringify!($SelfT), ".wrapping_cast());")]
4303 #[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX as i8, ", stringify!($SelfT), "::MAX.wrapping_cast());")]
4304 /// ```
4305 #[must_use = "this returns the cast result and does not modify the original"]
4306 #[unstable(feature = "integer_casts", issue = "157388")]
4307 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4308 #[inline(always)]
4309 pub const fn wrapping_cast<T: [const] BoundedCastFromInt<Self>>(self) -> T {
4310 T::wrapping_cast_from(self)
4311 }
4312
4313 /// Converts `self` to the target integer type, returning `None` if the value
4314 /// is not representable by the target type.
4315 ///
4316 /// # Examples
4317 ///
4318 /// ```
4319 /// #![feature(integer_casts)]
4320 #[doc = concat!("assert_eq!(Some(42u8), 42", stringify!($SelfT), ".checked_cast());")]
4321 #[doc = concat!("assert_eq!(128", stringify!($SelfT), ".checked_cast::<i8>(), None);")]
4322 /// ```
4323 #[must_use = "this returns the cast result and does not modify the original"]
4324 #[unstable(feature = "integer_casts", issue = "157388")]
4325 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4326 #[inline(always)]
4327 pub const fn checked_cast<T: [const] CheckedCastFromInt<Self>>(self) -> Option<T> {
4328 T::checked_cast_from(self)
4329 }
4330
4331 /// Converts `self` to the target integer type, panicking if the value
4332 /// is not representable by the target type.
4333 ///
4334 /// # Panics
4335 ///
4336 /// This function will panic if the value is not representable by the target type.
4337 ///
4338 /// # Examples
4339 ///
4340 /// ```
4341 /// #![feature(integer_casts)]
4342 #[doc = concat!("assert_eq!(42u8, 42", stringify!($SelfT), ".strict_cast());")]
4343 /// ```
4344 ///
4345 /// The following will panic:
4346 ///
4347 /// ```should_panic
4348 /// #![feature(integer_casts)]
4349 #[doc = concat!("let _ = 128", stringify!($SelfT), ".strict_cast::<i8>();")]
4350 /// ```
4351 #[must_use = "this returns the cast result and does not modify the original"]
4352 #[unstable(feature = "integer_casts", issue = "157388")]
4353 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4354 #[inline(always)]
4355 #[track_caller]
4356 pub const fn strict_cast<T: [const] CheckedCastFromInt<Self>>(self) -> T {
4357 T::strict_cast_from(self)
4358 }
4359
4360 /// Converts `self` to the target integer type, assuming the value is
4361 /// representable by the target type.
4362 ///
4363 /// # Safety
4364 ///
4365 /// This results in undefined behavior if the integer value of `self` is bigger than `T::MAX`,
4366 /// or smaller than `T::MIN`, where `T` is the target type.
4367 #[must_use = "this returns the cast result and does not modify the original"]
4368 #[unstable(feature = "integer_casts", issue = "157388")]
4369 #[rustc_const_unstable(feature = "integer_casts", issue = "157388")]
4370 #[inline(always)]
4371 pub const unsafe fn unchecked_cast<T: [const] CheckedCastFromInt<Self>>(self) -> T {
4372 assert_unsafe_precondition!(
4373 check_language_ub,
4374 concat!(stringify!($SelfT), "::unchecked_cast must fit in the target type"),
4375 (
4376 // Check has to be performed up-front because it depends on generic T.
4377 in_bounds: bool = {
4378 let cast_val = self.checked_cast::<T>();
4379 let ret = cast_val.is_some();
4380 core::mem::forget(cast_val); // We don't have const Drop, but we know it's an int.
4381 ret
4382 },
4383 ) => in_bounds,
4384 );
4385
4386 // SAFETY: this is guaranteed to be safe by the caller.
4387 unsafe { T::unchecked_cast_from(self) }
4388 }
4389 }
4390}