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1da177e4 LT |
1 | /* |
2 | * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com> | |
3 | * | |
4 | * Based on former do_div() implementation from asm-parisc/div64.h: | |
5 | * Copyright (C) 1999 Hewlett-Packard Co | |
6 | * Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com> | |
7 | * | |
8 | * | |
9 | * Generic C version of 64bit/32bit division and modulo, with | |
10 | * 64bit result and 32bit remainder. | |
11 | * | |
12 | * The fast case for (n>>32 == 0) is handled inline by do_div(). | |
13 | * | |
14 | * Code generated for this function might be very inefficient | |
15 | * for some CPUs. __div64_32() can be overridden by linking arch-specific | |
16 | * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S. | |
17 | */ | |
18 | ||
1da177e4 | 19 | #include <linux/module.h> |
2418f4f2 | 20 | #include <linux/math64.h> |
1da177e4 LT |
21 | |
22 | /* Not needed on 64bit architectures */ | |
23 | #if BITS_PER_LONG == 32 | |
24 | ||
cb8c181f | 25 | uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base) |
1da177e4 LT |
26 | { |
27 | uint64_t rem = *n; | |
28 | uint64_t b = base; | |
29 | uint64_t res, d = 1; | |
30 | uint32_t high = rem >> 32; | |
31 | ||
32 | /* Reduce the thing a bit first */ | |
33 | res = 0; | |
34 | if (high >= base) { | |
35 | high /= base; | |
36 | res = (uint64_t) high << 32; | |
37 | rem -= (uint64_t) (high*base) << 32; | |
38 | } | |
39 | ||
40 | while ((int64_t)b > 0 && b < rem) { | |
41 | b = b+b; | |
42 | d = d+d; | |
43 | } | |
44 | ||
45 | do { | |
46 | if (rem >= b) { | |
47 | rem -= b; | |
48 | res += d; | |
49 | } | |
50 | b >>= 1; | |
51 | d >>= 1; | |
52 | } while (d); | |
53 | ||
54 | *n = res; | |
55 | return rem; | |
56 | } | |
57 | ||
58 | EXPORT_SYMBOL(__div64_32); | |
59 | ||
2418f4f2 RZ |
60 | #ifndef div_s64_rem |
61 | s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder) | |
62 | { | |
63 | u64 quotient; | |
64 | ||
65 | if (dividend < 0) { | |
66 | quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder); | |
67 | *remainder = -*remainder; | |
68 | if (divisor > 0) | |
69 | quotient = -quotient; | |
70 | } else { | |
71 | quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder); | |
72 | if (divisor < 0) | |
73 | quotient = -quotient; | |
74 | } | |
75 | return quotient; | |
76 | } | |
77 | EXPORT_SYMBOL(div_s64_rem); | |
78 | #endif | |
79 | ||
3927f2e8 SH |
80 | /* 64bit divisor, dividend and result. dynamic precision */ |
81 | uint64_t div64_64(uint64_t dividend, uint64_t divisor) | |
82 | { | |
22b9a0a3 | 83 | uint32_t high, d; |
3927f2e8 | 84 | |
22b9a0a3 SH |
85 | high = divisor >> 32; |
86 | if (high) { | |
87 | unsigned int shift = fls(high); | |
3927f2e8 SH |
88 | |
89 | d = divisor >> shift; | |
90 | dividend >>= shift; | |
22b9a0a3 SH |
91 | } else |
92 | d = divisor; | |
3927f2e8 | 93 | |
22b9a0a3 | 94 | do_div(dividend, d); |
3927f2e8 SH |
95 | |
96 | return dividend; | |
97 | } | |
98 | EXPORT_SYMBOL(div64_64); | |
99 | ||
1da177e4 | 100 | #endif /* BITS_PER_LONG == 32 */ |