blob: 9a2d644c08efc0981dbc13b1700e81917fef7c63 [file] [log] [blame]
Chris Snook428c5a22007-10-20 07:51:29 -04001#ifndef _ASM_X86_DIV64_H
2#define _ASM_X86_DIV64_H
3
Thomas Gleixner96a388d2007-10-11 11:20:03 +02004#ifdef CONFIG_X86_32
Chris Snook428c5a22007-10-20 07:51:29 -04005
6#include <linux/types.h>
7
8/*
9 * do_div() is NOT a C function. It wants to return
10 * two values (the quotient and the remainder), but
11 * since that doesn't work very well in C, what it
12 * does is:
13 *
14 * - modifies the 64-bit dividend _in_place_
15 * - returns the 32-bit remainder
16 *
17 * This ends up being the most efficient "calling
18 * convention" on x86.
19 */
Joe Perches925a09b2008-03-23 01:01:59 -070020#define do_div(n, base) \
21({ \
22 unsigned long __upper, __low, __high, __mod, __base; \
23 __base = (base); \
24 asm("":"=a" (__low), "=d" (__high) : "A" (n)); \
25 __upper = __high; \
26 if (__high) { \
27 __upper = __high % (__base); \
28 __high = __high / (__base); \
29 } \
30 asm("divl %2":"=a" (__low), "=d" (__mod) \
31 : "rm" (__base), "0" (__low), "1" (__upper)); \
32 asm("":"=A" (n) : "a" (__low), "d" (__high)); \
33 __mod; \
Chris Snook428c5a22007-10-20 07:51:29 -040034})
35
Roman Zippel2418f4f2008-05-01 04:34:25 -070036static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
37{
38 union {
39 u64 v64;
40 u32 v32[2];
41 } d = { dividend };
42 u32 upper;
43
44 upper = d.v32[1];
45 d.v32[1] = 0;
46 if (upper >= divisor) {
47 d.v32[1] = upper / divisor;
48 upper %= divisor;
49 }
50 asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
51 "rm" (divisor), "0" (d.v32[0]), "1" (upper));
52 return d.v64;
53}
54#define div_u64_rem div_u64_rem
55
Thomas Gleixner96a388d2007-10-11 11:20:03 +020056#else
Chris Snook428c5a22007-10-20 07:51:29 -040057# include <asm-generic/div64.h>
58#endif /* CONFIG_X86_32 */
59
60#endif /* _ASM_X86_DIV64_H */