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101 lines
2.3 KiB
101 lines
2.3 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef _ASM_X86_DIV64_H |
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#define _ASM_X86_DIV64_H |
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#ifdef CONFIG_X86_32 |
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#include <linux/types.h> |
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#include <linux/log2.h> |
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/* |
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* do_div() is NOT a C function. It wants to return |
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* two values (the quotient and the remainder), but |
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* since that doesn't work very well in C, what it |
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* does is: |
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* |
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* - modifies the 64-bit dividend _in_place_ |
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* - returns the 32-bit remainder |
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* |
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* This ends up being the most efficient "calling |
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* convention" on x86. |
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*/ |
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#define do_div(n, base) \ |
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({ \ |
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unsigned long __upper, __low, __high, __mod, __base; \ |
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__base = (base); \ |
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if (__builtin_constant_p(__base) && is_power_of_2(__base)) { \ |
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__mod = n & (__base - 1); \ |
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n >>= ilog2(__base); \ |
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} else { \ |
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asm("" : "=a" (__low), "=d" (__high) : "A" (n));\ |
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__upper = __high; \ |
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if (__high) { \ |
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__upper = __high % (__base); \ |
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__high = __high / (__base); \ |
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} \ |
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asm("divl %2" : "=a" (__low), "=d" (__mod) \ |
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: "rm" (__base), "0" (__low), "1" (__upper)); \ |
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asm("" : "=A" (n) : "a" (__low), "d" (__high)); \ |
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} \ |
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__mod; \ |
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}) |
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static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) |
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{ |
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union { |
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u64 v64; |
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u32 v32[2]; |
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} d = { dividend }; |
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u32 upper; |
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upper = d.v32[1]; |
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d.v32[1] = 0; |
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if (upper >= divisor) { |
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d.v32[1] = upper / divisor; |
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upper %= divisor; |
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} |
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asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) : |
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"rm" (divisor), "0" (d.v32[0]), "1" (upper)); |
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return d.v64; |
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} |
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#define div_u64_rem div_u64_rem |
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static inline u64 mul_u32_u32(u32 a, u32 b) |
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{ |
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u32 high, low; |
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asm ("mull %[b]" : "=a" (low), "=d" (high) |
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: [a] "a" (a), [b] "rm" (b) ); |
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return low | ((u64)high) << 32; |
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} |
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#define mul_u32_u32 mul_u32_u32 |
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#else |
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# include <asm-generic/div64.h> |
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/* |
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* Will generate an #DE when the result doesn't fit u64, could fix with an |
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* __ex_table[] entry when it becomes an issue. |
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*/ |
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static inline u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div) |
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{ |
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u64 q; |
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asm ("mulq %2; divq %3" : "=a" (q) |
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: "a" (a), "rm" (mul), "rm" (div) |
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: "rdx"); |
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return q; |
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} |
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#define mul_u64_u64_div_u64 mul_u64_u64_div_u64 |
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static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div) |
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{ |
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return mul_u64_u64_div_u64(a, mul, div); |
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} |
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#define mul_u64_u32_div mul_u64_u32_div |
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#endif /* CONFIG_X86_32 */ |
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#endif /* _ASM_X86_DIV64_H */
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