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