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| Rev | Author | Line No. | Line |
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| 5270 | serge | 1 | #ifndef _ASM_X86_DIV64_H |
| 2 | #define _ASM_X86_DIV64_H |
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| 3 | |||
| 4 | #ifdef CONFIG_X86_32 |
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| 5 | |||
| 6 | #include |
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| 7 | #include |
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| 8 | |||
| 9 | /* |
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| 10 | * do_div() is NOT a C function. It wants to return |
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| 11 | * two values (the quotient and the remainder), but |
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| 12 | * since that doesn't work very well in C, what it |
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| 13 | * does is: |
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| 14 | * |
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| 15 | * - modifies the 64-bit dividend _in_place_ |
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| 16 | * - returns the 32-bit remainder |
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| 17 | * |
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| 18 | * This ends up being the most efficient "calling |
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| 19 | * convention" on x86. |
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| 20 | */ |
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| 21 | #define do_div(n, base) \ |
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| 22 | ({ \ |
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| 23 | unsigned long __upper, __low, __high, __mod, __base; \ |
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| 24 | __base = (base); \ |
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| 25 | if (__builtin_constant_p(__base) && is_power_of_2(__base)) { \ |
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| 26 | __mod = n & (__base - 1); \ |
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| 27 | n >>= ilog2(__base); \ |
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| 28 | } else { \ |
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| 29 | asm("" : "=a" (__low), "=d" (__high) : "A" (n));\ |
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| 30 | __upper = __high; \ |
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| 31 | if (__high) { \ |
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| 32 | __upper = __high % (__base); \ |
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| 33 | __high = __high / (__base); \ |
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| 34 | } \ |
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| 35 | asm("divl %2" : "=a" (__low), "=d" (__mod) \ |
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| 36 | : "rm" (__base), "0" (__low), "1" (__upper)); \ |
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| 37 | asm("" : "=A" (n) : "a" (__low), "d" (__high)); \ |
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| 38 | } \ |
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| 39 | __mod; \ |
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| 40 | }) |
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| 41 | |||
| 42 | static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) |
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| 43 | { |
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| 44 | union { |
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| 45 | u64 v64; |
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| 46 | u32 v32[2]; |
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| 47 | } d = { dividend }; |
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| 48 | u32 upper; |
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| 49 | |||
| 50 | upper = d.v32[1]; |
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| 51 | d.v32[1] = 0; |
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| 52 | if (upper >= divisor) { |
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| 53 | d.v32[1] = upper / divisor; |
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| 54 | upper %= divisor; |
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| 55 | } |
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| 56 | asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) : |
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| 57 | "rm" (divisor), "0" (d.v32[0]), "1" (upper)); |
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| 58 | return d.v64; |
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| 59 | } |
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| 60 | #define div_u64_rem div_u64_rem |
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| 61 | |||
| 62 | #else |
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| 63 | # include |
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| 64 | #endif /* CONFIG_X86_32 */ |
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| 65 | |||
| 66 | #endif /* _ASM_X86_DIV64_H */ |