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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 | |
19 | #include <linux/module.h> |
20 | #include <linux/math64.h> |
21 | |
22 | /* Not needed on 64bit architectures */ |
23 | #if BITS_PER_LONG == 32 |
24 | |
25 | uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base) |
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 | |
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 | |
80 | /* 64bit divisor, dividend and result. dynamic precision */ |
81 | #ifndef div64_u64 |
82 | u64 div64_u64(u64 dividend, u64 divisor) |
83 | { |
84 | u32 high, d; |
85 | |
86 | high = divisor >> 32; |
87 | if (high) { |
88 | unsigned int shift = fls(high); |
89 | |
90 | d = divisor >> shift; |
91 | dividend >>= shift; |
92 | } else |
93 | d = divisor; |
94 | |
95 | return div_u64(dividend, d); |
96 | } |
97 | EXPORT_SYMBOL(div64_u64); |
98 | #endif |
99 | |
100 | #endif /* BITS_PER_LONG == 32 */ |
101 | |
102 | /* |
103 | * Iterative div/mod for use when dividend is not expected to be much |
104 | * bigger than divisor. |
105 | */ |
106 | u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder) |
107 | { |
108 | return __iter_div_u64_rem(dividend, divisor, remainder); |
109 | } |
110 | EXPORT_SYMBOL(iter_div_u64_rem); |
111 |
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