#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 */