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1da177e4 LT |
1 | #ifndef __I386_DIV64 |
2 | #define __I386_DIV64 | |
3 | ||
4 | /* | |
5 | * do_div() is NOT a C function. It wants to return | |
6 | * two values (the quotient and the remainder), but | |
7 | * since that doesn't work very well in C, what it | |
8 | * does is: | |
9 | * | |
10 | * - modifies the 64-bit dividend _in_place_ | |
11 | * - returns the 32-bit remainder | |
12 | * | |
13 | * This ends up being the most efficient "calling | |
14 | * convention" on x86. | |
15 | */ | |
16 | #define do_div(n,base) ({ \ | |
17 | unsigned long __upper, __low, __high, __mod, __base; \ | |
18 | __base = (base); \ | |
19 | asm("":"=a" (__low), "=d" (__high):"A" (n)); \ | |
20 | __upper = __high; \ | |
21 | if (__high) { \ | |
22 | __upper = __high % (__base); \ | |
23 | __high = __high / (__base); \ | |
24 | } \ | |
25 | asm("divl %2":"=a" (__low), "=d" (__mod):"rm" (__base), "0" (__low), "1" (__upper)); \ | |
26 | asm("":"=A" (n):"a" (__low),"d" (__high)); \ | |
27 | __mod; \ | |
28 | }) | |
29 | ||
30 | /* | |
31 | * (long)X = ((long long)divs) / (long)div | |
32 | * (long)rem = ((long long)divs) % (long)div | |
33 | * | |
34 | * Warning, this will do an exception if X overflows. | |
35 | */ | |
36 | #define div_long_long_rem(a,b,c) div_ll_X_l_rem(a,b,c) | |
37 | ||
e2afe674 | 38 | static inline long |
1da177e4 LT |
39 | div_ll_X_l_rem(long long divs, long div, long *rem) |
40 | { | |
41 | long dum2; | |
42 | __asm__("divl %2":"=a"(dum2), "=d"(*rem) | |
43 | : "rm"(div), "A"(divs)); | |
44 | ||
45 | return dum2; | |
46 | ||
47 | } | |
48 | #endif |