include/linux/math64.h

1 /* SPDX-License-Identifier: GPL-2.0 */
16  * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
17  * @dividend: unsigned 64bit dividend
18  * @divisor: unsigned 32bit divisor
19  * @remainder: pointer to unsigned 32bit remainder
23  * This is commonly provided by 32bit archs to provide an optimized 64bit
33  * div_s64_rem - signed 64bit divide with 32bit divisor with remainder
34  * @dividend: signed 64bit dividend
35  * @divisor: signed 32bit divisor
36  * @remainder: pointer to signed 32bit remainder
47  * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
48  * @dividend: unsigned 64bit dividend
49  * @divisor: unsigned 64bit divisor
50  * @remainder: pointer to unsigned 64bit remainder
61  * div64_u64 - unsigned 64bit divide with 64bit divisor
62  * @dividend: unsigned 64bit dividend
63  * @divisor: unsigned 64bit divisor
73  * div64_s64 - signed 64bit divide with 64bit divisor
74  * @dividend: signed 64bit dividend
75  * @divisor: signed 64bit divisor
84 #elif BITS_PER_LONG == 32
116  * div_u64 - unsigned 64bit divide with 32bit divisor
117  * @dividend: unsigned 64bit dividend
118  * @divisor: unsigned 32bit divisor
120  * This is the most common 64bit divide and should be used if possible,
121  * as many 32bit archs can optimize this variant better than a full 64bit
135  * div_s64 - signed 64bit divide with 32bit divisor
136  * @dividend: signed 64bit dividend
137  * @divisor: signed 32bit divisor
153  * Many a GCC version messes this up and generates a 64x64 mult :-(
182 	u32 ah = a >> 32, al = a;  in mul_u64_u32_shr()
187 		ret += mul_u32_u32(ah, mul) << (32 - shift);  in mul_u64_u32_shr()
216 	 * Each of these lines computes a 64-bit intermediate result into "c",  in mul_u64_u64_shr()
217 	 * starting at bits 32-95.  The low 32-bits go into the result of the  in mul_u64_u64_shr()
218 	 * multiplication, the high 32-bits are carried into the next step.  in mul_u64_u64_shr()
221 	rh.l.low = c = (c >> 32) + rm.l.high + rn.l.high + rh.l.low;  in mul_u64_u64_shr()
222 	rh.l.high = (c >> 32) + rh.l.high;  in mul_u64_u64_shr()
225 	 * The 128-bit result of the multiplication is in rl.ll and rh.ll,  in mul_u64_u64_shr()
231 		return (rl.ll >> shift) | (rh.ll << (64 - shift));  in mul_u64_u64_shr()
250 		ret = -((s64) ret);  in mul_s64_u64_shr()
274 	/* Bits 32-63 of the result will be in rh.l.low. */  in mul_u64_u32_div()
277 	/* Bits 0-31 of the result will be in rl.l.low.	*/  in mul_u64_u32_div()
288  * DIV64_U64_ROUND_UP - unsigned 64bit divide with 64bit divisor rounded up
289  * @ll: unsigned 64bit dividend
290  * @d: unsigned 64bit divisor
292  * Divide unsigned 64bit dividend by unsigned 64bit divisor
298 	({ u64 _tmp = (d); div64_u64((ll) + _tmp - 1, _tmp); })
301  * DIV_U64_ROUND_UP - unsigned 64bit divide with 32bit divisor rounded up
302  * @ll: unsigned 64bit dividend
303  * @d: unsigned 32bit divisor
305  * Divide unsigned 64bit dividend by unsigned 32bit divisor
311 	({ u32 _tmp = (d); div_u64((ll) + _tmp - 1, _tmp); })
314  * DIV64_U64_ROUND_CLOSEST - unsigned 64bit divide with 64bit divisor rounded to nearest integer
315  * @dividend: unsigned 64bit dividend
316  * @divisor: unsigned 64bit divisor
318  * Divide unsigned 64bit dividend by unsigned 64bit divisor
327  * DIV_U64_ROUND_CLOSEST - unsigned 64bit divide with 32bit divisor rounded to nearest integer
328  * @dividend: unsigned 64bit dividend
329  * @divisor: unsigned 32bit divisor
331  * Divide unsigned 64bit dividend by unsigned 32bit divisor
340  * DIV_S64_ROUND_CLOSEST - signed 64bit divide with 32bit divisor rounded to nearest integer
341  * @dividend: signed 64bit dividend
342  * @divisor: signed 32bit divisor
344  * Divide signed 64bit dividend by signed 32bit divisor
355 		div_s64((__x - (__d / 2)), __d);	\
360  * roundup_u64 - Round up a 64bit value to the next specified 32bit multiple
362  * @y: 32bit multiple to round up to
364  * Rounds @x to the next multiple of @y. For 32bit @x values, see roundup and