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
div_ll_X_l_rem(long long divs,long div,long * rem)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