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author | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
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committer | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
commit | 871480933a1c28f8a9fed4c4d34d06c439a7a422 (patch) | |
tree | 8718f573808810c2a1e8cb8fb6ac469093ca2784 /arch/x86/include/asm/div64.h | |
parent | 9d40ac5867b9aefe0722bc1f110b965ff294d30d (diff) | |
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Moved, renamed, and deleted files
The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.
Diffstat (limited to 'arch/x86/include/asm/div64.h')
-rw-r--r-- | arch/x86/include/asm/div64.h | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/arch/x86/include/asm/div64.h b/arch/x86/include/asm/div64.h new file mode 100644 index 00000000..ced283ac --- /dev/null +++ b/arch/x86/include/asm/div64.h @@ -0,0 +1,66 @@ +#ifndef _ASM_X86_DIV64_H +#define _ASM_X86_DIV64_H + +#ifdef CONFIG_X86_32 + +#include <linux/types.h> +#include <linux/log2.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); \ + if (__builtin_constant_p(__base) && is_power_of_2(__base)) { \ + __mod = n & (__base - 1); \ + n >>= ilog2(__base); \ + } else { \ + 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 */ |