1#ifndef _ASM_X86_DIV64_H
 2#define _ASM_X86_DIV64_H
 3
 4#ifdef CONFIG_X86_32
 5
 6#include <linux/types.h>
 7#include <linux/log2.h>
 8
 9/*
10 * do_div() is NOT a C function. It wants to return
11 * two values (the quotient and the remainder), but
12 * since that doesn't work very well in C, what it
13 * does is:
14 *
15 * - modifies the 64-bit dividend _in_place_
16 * - returns the 32-bit remainder
17 *
18 * This ends up being the most efficient "calling
19 * convention" on x86.
20 */
21#define do_div(n, base)						\
22({								\
23	unsigned long __upper, __low, __high, __mod, __base;	\
24	__base = (base);					\
25	if (__builtin_constant_p(__base) && is_power_of_2(__base)) { \
26		__mod = n & (__base - 1);			\
27		n >>= ilog2(__base);				\
28	} else {						\
29		asm("" : "=a" (__low), "=d" (__high) : "A" (n));\
30		__upper = __high;				\
31		if (__high) {					\
32			__upper = __high % (__base);		\
33			__high = __high / (__base);		\
34		}						\
35		asm("divl %2" : "=a" (__low), "=d" (__mod)	\
36			: "rm" (__base), "0" (__low), "1" (__upper));	\
37		asm("" : "=A" (n) : "a" (__low), "d" (__high));	\
38	}							\
39	__mod;							\
40})
41
42static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
43{
44	union {
45		u64 v64;
46		u32 v32[2];
47	} d = { dividend };
48	u32 upper;
49
50	upper = d.v32[1];
51	d.v32[1] = 0;
52	if (upper >= divisor) {
53		d.v32[1] = upper / divisor;
54		upper %= divisor;
55	}
56	asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
57		"rm" (divisor), "0" (d.v32[0]), "1" (upper));
58	return d.v64;
59}
60#define div_u64_rem	div_u64_rem
61
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
62#else
63# include <asm-generic/div64.h>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
64#endif /* CONFIG_X86_32 */
65
66#endif /* _ASM_X86_DIV64_H */

  1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef _ASM_X86_DIV64_H
  3#define _ASM_X86_DIV64_H
  4
  5#ifdef CONFIG_X86_32
  6
  7#include <linux/types.h>
  8#include <linux/log2.h>
  9
 10/*
 11 * do_div() is NOT a C function. It wants to return
 12 * two values (the quotient and the remainder), but
 13 * since that doesn't work very well in C, what it
 14 * does is:
 15 *
 16 * - modifies the 64-bit dividend _in_place_
 17 * - returns the 32-bit remainder
 18 *
 19 * This ends up being the most efficient "calling
 20 * convention" on x86.
 21 */
 22#define do_div(n, base)						\
 23({								\
 24	unsigned long __upper, __low, __high, __mod, __base;	\
 25	__base = (base);					\
 26	if (__builtin_constant_p(__base) && is_power_of_2(__base)) { \
 27		__mod = n & (__base - 1);			\
 28		n >>= ilog2(__base);				\
 29	} else {						\
 30		asm("" : "=a" (__low), "=d" (__high) : "A" (n));\
 31		__upper = __high;				\
 32		if (__high) {					\
 33			__upper = __high % (__base);		\
 34			__high = __high / (__base);		\
 35		}						\
 36		asm("divl %2" : "=a" (__low), "=d" (__mod)	\
 37			: "rm" (__base), "0" (__low), "1" (__upper));	\
 38		asm("" : "=A" (n) : "a" (__low), "d" (__high));	\
 39	}							\
 40	__mod;							\
 41})
 42
 43static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
 44{
 45	union {
 46		u64 v64;
 47		u32 v32[2];
 48	} d = { dividend };
 49	u32 upper;
 50
 51	upper = d.v32[1];
 52	d.v32[1] = 0;
 53	if (upper >= divisor) {
 54		d.v32[1] = upper / divisor;
 55		upper %= divisor;
 56	}
 57	asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
 58		"rm" (divisor), "0" (d.v32[0]), "1" (upper));
 59	return d.v64;
 60}
 61#define div_u64_rem	div_u64_rem
 62
 63static inline u64 mul_u32_u32(u32 a, u32 b)
 64{
 65	u32 high, low;
 66
 67	asm ("mull %[b]" : "=a" (low), "=d" (high)
 68			 : [a] "a" (a), [b] "rm" (b) );
 69
 70	return low | ((u64)high) << 32;
 71}
 72#define mul_u32_u32 mul_u32_u32
 73
 74/*
 75 * __div64_32() is never called on x86, so prevent the
 76 * generic definition from getting built.
 77 */
 78#define __div64_32
 79
 80#else
 81# include <asm-generic/div64.h>
 82
 83/*
 84 * Will generate an #DE when the result doesn't fit u64, could fix with an
 85 * __ex_table[] entry when it becomes an issue.
 86 */
 87static inline u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div)
 88{
 89	u64 q;
 90
 91	asm ("mulq %2; divq %3" : "=a" (q)
 92				: "a" (a), "rm" (mul), "rm" (div)
 93				: "rdx");
 94
 95	return q;
 96}
 97#define mul_u64_u64_div_u64 mul_u64_u64_div_u64
 98
 99static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div)
100{
101	return mul_u64_u64_div_u64(a, mul, div);
102}
103#define mul_u64_u32_div	mul_u64_u32_div
104
105#endif /* CONFIG_X86_32 */
106
107#endif /* _ASM_X86_DIV64_H */