diff options
author | Ingo Molnar <mingo@elte.hu> | 2008-10-27 10:50:54 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-10-27 10:50:54 +0100 |
commit | 4944dd62de21230af039eda7cd218e9a09021d11 (patch) | |
tree | bac70f7bab8506c7e1b0408bacbdb0b1d77262e9 /arch/x86/include/asm/div64.h | |
parent | f17845e5d97ead8fbdadfd40039e058ec7cf4a42 (diff) | |
parent | 0173a3265b228da319ceb9c1ec6a5682fd1b2d92 (diff) |
Merge commit 'v2.6.28-rc2' into tracing/urgent
Diffstat (limited to 'arch/x86/include/asm/div64.h')
-rw-r--r-- | arch/x86/include/asm/div64.h | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/arch/x86/include/asm/div64.h b/arch/x86/include/asm/div64.h new file mode 100644 index 00000000000..9a2d644c08e --- /dev/null +++ b/arch/x86/include/asm/div64.h @@ -0,0 +1,60 @@ +#ifndef _ASM_X86_DIV64_H +#define _ASM_X86_DIV64_H + +#ifdef CONFIG_X86_32 + +#include <linux/types.h> + +/* + * do_div() is NOT a C function. It wants to return + * two values (the quotient and the remainder), but + * since that doesn't work very well in C, what it + * does is: + * + * - modifies the 64-bit dividend _in_place_ + * - returns the 32-bit remainder + * + * This ends up being the most efficient "calling + * convention" on x86. + */ +#define do_div(n, base) \ +({ \ + unsigned long __upper, __low, __high, __mod, __base; \ + __base = (base); \ + asm("":"=a" (__low), "=d" (__high) : "A" (n)); \ + __upper = __high; \ + if (__high) { \ + __upper = __high % (__base); \ + __high = __high / (__base); \ + } \ + asm("divl %2":"=a" (__low), "=d" (__mod) \ + : "rm" (__base), "0" (__low), "1" (__upper)); \ + asm("":"=A" (n) : "a" (__low), "d" (__high)); \ + __mod; \ +}) + +static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) +{ + union { + u64 v64; + u32 v32[2]; + } d = { dividend }; + u32 upper; + + upper = d.v32[1]; + d.v32[1] = 0; + if (upper >= divisor) { + d.v32[1] = upper / divisor; + upper %= divisor; + } + asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) : + "rm" (divisor), "0" (d.v32[0]), "1" (upper)); + return d.v64; +} +#define div_u64_rem div_u64_rem + +#else +# include <asm-generic/div64.h> +#endif /* CONFIG_X86_32 */ + +#endif /* _ASM_X86_DIV64_H */ |