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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// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com>
4 *
5 * Based on former do_div() implementation from asm-parisc/div64.h:
6 * Copyright (C) 1999 Hewlett-Packard Co
7 * Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
8 *
9 *
10 * Generic C version of 64bit/32bit division and modulo, with
11 * 64bit result and 32bit remainder.
12 *
13 * The fast case for (n>>32 == 0) is handled inline by do_div().
14 *
15 * Code generated for this function might be very inefficient
16 * for some CPUs. __div64_32() can be overridden by linking arch-specific
17 * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S
18 * or by defining a preprocessor macro in arch/include/asm/div64.h.
19 */
20
21#include <linux/export.h>
22#include <linux/kernel.h>
23#include <linux/math64.h>
24
25/* Not needed on 64bit architectures */
26#if BITS_PER_LONG == 32
27
28#ifndef __div64_32
29uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base)
30{
31 uint64_t rem = *n;
32 uint64_t b = base;
33 uint64_t res, d = 1;
34 uint32_t high = rem >> 32;
35
36 /* Reduce the thing a bit first */
37 res = 0;
38 if (high >= base) {
39 high /= base;
40 res = (uint64_t) high << 32;
41 rem -= (uint64_t) (high*base) << 32;
42 }
43
44 while ((int64_t)b > 0 && b < rem) {
45 b = b+b;
46 d = d+d;
47 }
48
49 do {
50 if (rem >= b) {
51 rem -= b;
52 res += d;
53 }
54 b >>= 1;
55 d >>= 1;
56 } while (d);
57
58 *n = res;
59 return rem;
60}
61EXPORT_SYMBOL(__div64_32);
62#endif
63
64/**
65 * div_s64_rem - signed 64bit divide with 64bit divisor and remainder
66 * @dividend: 64bit dividend
67 * @divisor: 64bit divisor
68 * @remainder: 64bit remainder
69 */
70#ifndef div_s64_rem
71s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
72{
73 u64 quotient;
74
75 if (dividend < 0) {
76 quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
77 *remainder = -*remainder;
78 if (divisor > 0)
79 quotient = -quotient;
80 } else {
81 quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
82 if (divisor < 0)
83 quotient = -quotient;
84 }
85 return quotient;
86}
87EXPORT_SYMBOL(div_s64_rem);
88#endif
89
90/**
91 * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
92 * @dividend: 64bit dividend
93 * @divisor: 64bit divisor
94 * @remainder: 64bit remainder
95 *
96 * This implementation is a comparable to algorithm used by div64_u64.
97 * But this operation, which includes math for calculating the remainder,
98 * is kept distinct to avoid slowing down the div64_u64 operation on 32bit
99 * systems.
100 */
101#ifndef div64_u64_rem
102u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
103{
104 u32 high = divisor >> 32;
105 u64 quot;
106
107 if (high == 0) {
108 u32 rem32;
109 quot = div_u64_rem(dividend, divisor, &rem32);
110 *remainder = rem32;
111 } else {
112 int n = 1 + fls(high);
113 quot = div_u64(dividend >> n, divisor >> n);
114
115 if (quot != 0)
116 quot--;
117
118 *remainder = dividend - quot * divisor;
119 if (*remainder >= divisor) {
120 quot++;
121 *remainder -= divisor;
122 }
123 }
124
125 return quot;
126}
127EXPORT_SYMBOL(div64_u64_rem);
128#endif
129
130/**
131 * div64_u64 - unsigned 64bit divide with 64bit divisor
132 * @dividend: 64bit dividend
133 * @divisor: 64bit divisor
134 *
135 * This implementation is a modified version of the algorithm proposed
136 * by the book 'Hacker's Delight'. The original source and full proof
137 * can be found here and is available for use without restriction.
138 *
139 * 'http://www.hackersdelight.org/hdcodetxt/divDouble.c.txt'
140 */
141#ifndef div64_u64
142u64 div64_u64(u64 dividend, u64 divisor)
143{
144 u32 high = divisor >> 32;
145 u64 quot;
146
147 if (high == 0) {
148 quot = div_u64(dividend, divisor);
149 } else {
150 int n = 1 + fls(high);
151 quot = div_u64(dividend >> n, divisor >> n);
152
153 if (quot != 0)
154 quot--;
155 if ((dividend - quot * divisor) >= divisor)
156 quot++;
157 }
158
159 return quot;
160}
161EXPORT_SYMBOL(div64_u64);
162#endif
163
164/**
165 * div64_s64 - signed 64bit divide with 64bit divisor
166 * @dividend: 64bit dividend
167 * @divisor: 64bit divisor
168 */
169#ifndef div64_s64
170s64 div64_s64(s64 dividend, s64 divisor)
171{
172 s64 quot, t;
173
174 quot = div64_u64(abs(dividend), abs(divisor));
175 t = (dividend ^ divisor) >> 63;
176
177 return (quot ^ t) - t;
178}
179EXPORT_SYMBOL(div64_s64);
180#endif
181
182#endif /* BITS_PER_LONG == 32 */
183
184/*
185 * Iterative div/mod for use when dividend is not expected to be much
186 * bigger than divisor.
187 */
188u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
189{
190 return __iter_div_u64_rem(dividend, divisor, remainder);
191}
192EXPORT_SYMBOL(iter_div_u64_rem);