Chris Snook | 428c5a2 | 2007-10-20 07:51:29 -0400 | [diff] [blame] | 1 | #ifndef _ASM_X86_DIV64_H |
| 2 | #define _ASM_X86_DIV64_H |
| 3 | |
Thomas Gleixner | 96a388d | 2007-10-11 11:20:03 +0200 | [diff] [blame] | 4 | #ifdef CONFIG_X86_32 |
Chris Snook | 428c5a2 | 2007-10-20 07:51:29 -0400 | [diff] [blame] | 5 | |
| 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 Perches | 925a09b | 2008-03-23 01:01:59 -0700 | [diff] [blame] | 20 | #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 Snook | 428c5a2 | 2007-10-20 07:51:29 -0400 | [diff] [blame] | 34 | }) |
| 35 | |
Roman Zippel | 2418f4f | 2008-05-01 04:34:25 -0700 | [diff] [blame] | 36 | static 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 Gleixner | 96a388d | 2007-10-11 11:20:03 +0200 | [diff] [blame] | 56 | #else |
Chris Snook | 428c5a2 | 2007-10-20 07:51:29 -0400 | [diff] [blame] | 57 | # include <asm-generic/div64.h> |
| 58 | #endif /* CONFIG_X86_32 */ |
| 59 | |
| 60 | #endif /* _ASM_X86_DIV64_H */ |