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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/export.h>
20#include <linux/kernel.h>
21#include <linux/math64.h>
22
23/* Not needed on 64bit architectures */
24#if BITS_PER_LONG == 32
25
26uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base)
27{
28 uint64_t rem = *n;
29 uint64_t b = base;
30 uint64_t res, d = 1;
31 uint32_t high = rem >> 32;
32
33 /* Reduce the thing a bit first */
34 res = 0;
35 if (high >= base) {
36 high /= base;
37 res = (uint64_t) high << 32;
38 rem -= (uint64_t) (high*base) << 32;
39 }
40
41 while ((int64_t)b > 0 && b < rem) {
42 b = b+b;
43 d = d+d;
44 }
45
46 do {
47 if (rem >= b) {
48 rem -= b;
49 res += d;
50 }
51 b >>= 1;
52 d >>= 1;
53 } while (d);
54
55 *n = res;
56 return rem;
57}
58
59EXPORT_SYMBOL(__div64_32);
60
61#ifndef div_s64_rem
62s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
63{
64 u64 quotient;
65
66 if (dividend < 0) {
67 quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
68 *remainder = -*remainder;
69 if (divisor > 0)
70 quotient = -quotient;
71 } else {
72 quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
73 if (divisor < 0)
74 quotient = -quotient;
75 }
76 return quotient;
77}
78EXPORT_SYMBOL(div_s64_rem);
79#endif
80
81/**
82 * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
83 * @dividend: 64bit dividend
84 * @divisor: 64bit divisor
85 * @remainder: 64bit remainder
86 *
87 * This implementation is a comparable to algorithm used by div64_u64.
88 * But this operation, which includes math for calculating the remainder,
89 * is kept distinct to avoid slowing down the div64_u64 operation on 32bit
90 * systems.
91 */
92#ifndef div64_u64_rem
93u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
94{
95 u32 high = divisor >> 32;
96 u64 quot;
97
98 if (high == 0) {
99 u32 rem32;
100 quot = div_u64_rem(dividend, divisor, &rem32);
101 *remainder = rem32;
102 } else {
103 int n = 1 + fls(high);
104 quot = div_u64(dividend >> n, divisor >> n);
105
106 if (quot != 0)
107 quot--;
108
109 *remainder = dividend - quot * divisor;
110 if (*remainder >= divisor) {
111 quot++;
112 *remainder -= divisor;
113 }
114 }
115
116 return quot;
117}
118EXPORT_SYMBOL(div64_u64_rem);
119#endif
120
121/**
122 * div64_u64 - unsigned 64bit divide with 64bit divisor
123 * @dividend: 64bit dividend
124 * @divisor: 64bit divisor
125 *
126 * This implementation is a modified version of the algorithm proposed
127 * by the book 'Hacker's Delight'. The original source and full proof
128 * can be found here and is available for use without restriction.
129 *
130 * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c.txt'
131 */
132#ifndef div64_u64
133u64 div64_u64(u64 dividend, u64 divisor)
134{
135 u32 high = divisor >> 32;
136 u64 quot;
137
138 if (high == 0) {
139 quot = div_u64(dividend, divisor);
140 } else {
141 int n = 1 + fls(high);
142 quot = div_u64(dividend >> n, divisor >> n);
143
144 if (quot != 0)
145 quot--;
146 if ((dividend - quot * divisor) >= divisor)
147 quot++;
148 }
149
150 return quot;
151}
152EXPORT_SYMBOL(div64_u64);
153#endif
154
155/**
156 * div64_s64 - signed 64bit divide with 64bit divisor
157 * @dividend: 64bit dividend
158 * @divisor: 64bit divisor
159 */
160#ifndef div64_s64
161s64 div64_s64(s64 dividend, s64 divisor)
162{
163 s64 quot, t;
164
165 quot = div64_u64(abs64(dividend), abs64(divisor));
166 t = (dividend ^ divisor) >> 63;
167
168 return (quot ^ t) - t;
169}
170EXPORT_SYMBOL(div64_s64);
171#endif
172
173#endif /* BITS_PER_LONG == 32 */
174
175/*
176 * Iterative div/mod for use when dividend is not expected to be much
177 * bigger than divisor.
178 */
179u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
180{
181 return __iter_div_u64_rem(dividend, divisor, remainder);
182}
183EXPORT_SYMBOL(iter_div_u64_rem);
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
25uint32_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
58EXPORT_SYMBOL(__div64_32);
59
60#ifndef div_s64_rem
61s64 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}
77EXPORT_SYMBOL(div_s64_rem);
78#endif
79
80/**
81 * div64_u64 - unsigned 64bit divide with 64bit divisor
82 * @dividend: 64bit dividend
83 * @divisor: 64bit divisor
84 *
85 * This implementation is a modified version of the algorithm proposed
86 * by the book 'Hacker's Delight'. The original source and full proof
87 * can be found here and is available for use without restriction.
88 *
89 * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c'
90 */
91#ifndef div64_u64
92u64 div64_u64(u64 dividend, u64 divisor)
93{
94 u32 high = divisor >> 32;
95 u64 quot;
96
97 if (high == 0) {
98 quot = div_u64(dividend, divisor);
99 } else {
100 int n = 1 + fls(high);
101 quot = div_u64(dividend >> n, divisor >> n);
102
103 if (quot != 0)
104 quot--;
105 if ((dividend - quot * divisor) >= divisor)
106 quot++;
107 }
108
109 return quot;
110}
111EXPORT_SYMBOL(div64_u64);
112#endif
113
114/**
115 * div64_s64 - signed 64bit divide with 64bit divisor
116 * @dividend: 64bit dividend
117 * @divisor: 64bit divisor
118 */
119#ifndef div64_s64
120s64 div64_s64(s64 dividend, s64 divisor)
121{
122 s64 quot, t;
123
124 quot = div64_u64(abs64(dividend), abs64(divisor));
125 t = (dividend ^ divisor) >> 63;
126
127 return (quot ^ t) - t;
128}
129EXPORT_SYMBOL(div64_s64);
130#endif
131
132#endif /* BITS_PER_LONG == 32 */
133
134/*
135 * Iterative div/mod for use when dividend is not expected to be much
136 * bigger than divisor.
137 */
138u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
139{
140 return __iter_div_u64_rem(dividend, divisor, remainder);
141}
142EXPORT_SYMBOL(iter_div_u64_rem);