1 #ifndef _ASM_X86_DIV64_H 2 #define _ASM_X86_DIV64_H 3 4 #ifdef CONFIG_X86_32 5 6 #include <linux/types.h> 7 8 /* 9 * do_div() is NOT a C function. It wants to return 10 * two values (the quotient and the remainder), but 11 * since that doesn't work very well in C, what it 12 * does is: 13 * 14 * - modifies the 64-bit dividend _in_place_ 15 * - returns the 32-bit remainder 16 * 17 * This ends up being the most efficient "calling 18 * convention" on x86. 19 */ 20 #define do_div(n,base) ({ \ 21 unsigned long __upper, __low, __high, __mod, __base; \ 22 __base = (base); \ 23 asm("":"=a" (__low), "=d" (__high):"A" (n)); \ 24 __upper = __high; \ 25 if (__high) { \ 26 __upper = __high % (__base); \ 27 __high = __high / (__base); \ 28 } \ 29 asm("divl %2":"=a" (__low), "=d" (__mod):"rm" (__base), "0" (__low), "1" (__upper)); \ 30 asm("":"=A" (n):"a" (__low),"d" (__high)); \ 31 __mod; \ 32 }) 33 34 /* 35 * (long)X = ((long long)divs) / (long)div 36 * (long)rem = ((long long)divs) % (long)div 37 * 38 * Warning, this will do an exception if X overflows. 39 */ 40 #define div_long_long_rem(a,b,c) div_ll_X_l_rem(a,b,c) 41 42 static inline long 43 div_ll_X_l_rem(long long divs, long div, long *rem) 44 { 45 long dum2; 46 __asm__("divl %2":"=a"(dum2), "=d"(*rem) 47 : "rm"(div), "A"(divs)); 48 49 return dum2; 50 51 } 52 53 extern uint64_t div64_64(uint64_t dividend, uint64_t divisor); 54 55 #else 56 # include <asm-generic/div64.h> 57 #endif /* CONFIG_X86_32 */ 58 59 #endif /* _ASM_X86_DIV64_H */ 60
