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1965aae3 PA |
1 | #ifndef _ASM_X86_DIV64_H |
2 | #define _ASM_X86_DIV64_H | |
428c5a23 | 3 | |
96a388de | 4 | #ifdef CONFIG_X86_32 |
428c5a23 CS |
5 | |
6 | #include <linux/types.h> | |
668b4484 | 7 | #include <linux/log2.h> |
428c5a23 CS |
8 | |
9 | /* | |
10 | * do_div() is NOT a C function. It wants to return | |
11 | * two values (the quotient and the remainder), but | |
12 | * since that doesn't work very well in C, what it | |
13 | * does is: | |
14 | * | |
15 | * - modifies the 64-bit dividend _in_place_ | |
16 | * - returns the 32-bit remainder | |
17 | * | |
18 | * This ends up being the most efficient "calling | |
19 | * convention" on x86. | |
20 | */ | |
925a09b2 JP |
21 | #define do_div(n, base) \ |
22 | ({ \ | |
23 | unsigned long __upper, __low, __high, __mod, __base; \ | |
24 | __base = (base); \ | |
668b4484 SAS |
25 | if (__builtin_constant_p(__base) && is_power_of_2(__base)) { \ |
26 | __mod = n & (__base - 1); \ | |
27 | n >>= ilog2(__base); \ | |
28 | } else { \ | |
29 | asm("" : "=a" (__low), "=d" (__high) : "A" (n));\ | |
30 | __upper = __high; \ | |
31 | if (__high) { \ | |
32 | __upper = __high % (__base); \ | |
33 | __high = __high / (__base); \ | |
34 | } \ | |
35 | asm("divl %2" : "=a" (__low), "=d" (__mod) \ | |
36 | : "rm" (__base), "0" (__low), "1" (__upper)); \ | |
37 | asm("" : "=A" (n) : "a" (__low), "d" (__high)); \ | |
925a09b2 | 38 | } \ |
925a09b2 | 39 | __mod; \ |
428c5a23 CS |
40 | }) |
41 | ||
2418f4f2 RZ |
42 | static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) |
43 | { | |
44 | union { | |
45 | u64 v64; | |
46 | u32 v32[2]; | |
47 | } d = { dividend }; | |
48 | u32 upper; | |
49 | ||
50 | upper = d.v32[1]; | |
51 | d.v32[1] = 0; | |
52 | if (upper >= divisor) { | |
53 | d.v32[1] = upper / divisor; | |
54 | upper %= divisor; | |
55 | } | |
56 | asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) : | |
57 | "rm" (divisor), "0" (d.v32[0]), "1" (upper)); | |
58 | return d.v64; | |
59 | } | |
60 | #define div_u64_rem div_u64_rem | |
61 | ||
96a388de | 62 | #else |
428c5a23 CS |
63 | # include <asm-generic/div64.h> |
64 | #endif /* CONFIG_X86_32 */ | |
65 | ||
1965aae3 | 66 | #endif /* _ASM_X86_DIV64_H */ |