source: mainline/kernel/genarch/src/softint/division.c

Last change on this file was 6404aca, checked in by Jakub Jermar <jakub@…>, 7 years ago

Disambiguate doxygroup genarch*
  • Property mode set to 100644
File size: 5.1 KB
Line 
1/*
2 * Copyright (c) 2006 Josef Cejka
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/** @addtogroup kernel_genarch
30 * @{
31 */
32/** @file
33 */
34
35#include <genarch/softint/division.h>
36
37#define ABSVAL(x) ((x) > 0 ? (x) : -(x))
38#define SGN(x) ((x) >= 0 ? 1 : 0)
39
40static unsigned int divandmod32(unsigned int a, unsigned int b,
41 unsigned int *remainder)
42{
43 unsigned int result;
44 int steps = sizeof(unsigned int) * 8;
45
46 *remainder = 0;
47 result = 0;
48
49 if (b == 0) {
50 /* FIXME: division by zero */
51 return 0;
52 }
53
54 if (a < b) {
55 *remainder = a;
56 return 0;
57 }
58
59 for (; steps > 0; steps--) {
60 /* shift one bit to remainder */
61 *remainder = ((*remainder) << 1) | ((a >> 31) & 0x1);
62 result <<= 1;
63
64 if (*remainder >= b) {
65 *remainder -= b;
66 result |= 0x1;
67 }
68 a <<= 1;
69 }
70
71 return result;
72}
73
74static unsigned long long divandmod64(unsigned long long a,
75 unsigned long long b, unsigned long long *remainder)
76{
77 unsigned long long result;
78 int steps = sizeof(unsigned long long) * 8;
79
80 *remainder = 0;
81 result = 0;
82
83 if (b == 0) {
84 /* FIXME: division by zero */
85 return 0;
86 }
87
88 if (a < b) {
89 *remainder = a;
90 return 0;
91 }
92
93 for (; steps > 0; steps--) {
94 /* shift one bit to remainder */
95 *remainder = ((*remainder) << 1) | ((a >> 63) & 0x1);
96 result <<= 1;
97
98 if (*remainder >= b) {
99 *remainder -= b;
100 result |= 0x1;
101 }
102 a <<= 1;
103 }
104
105 return result;
106}
107
108/* 32bit integer division */
109int __divsi3(int a, int b)
110{
111 unsigned int rem;
112 int result = (int) divandmod32(ABSVAL(a), ABSVAL(b), &rem);
113
114 if (SGN(a) == SGN(b))
115 return result;
116
117 return -result;
118}
119
120/* 64bit integer division */
121long long __divdi3(long long a, long long b)
122{
123 unsigned long long rem;
124 long long result = (long long) divandmod64(ABSVAL(a), ABSVAL(b), &rem);
125
126 if (SGN(a) == SGN(b))
127 return result;
128
129 return -result;
130}
131
132/* 32bit unsigned integer division */
133unsigned int __udivsi3(unsigned int a, unsigned int b)
134{
135 unsigned int rem;
136 return divandmod32(a, b, &rem);
137}
138
139/* 64bit unsigned integer division */
140unsigned long long __udivdi3(unsigned long long a, unsigned long long b)
141{
142 unsigned long long rem;
143 return divandmod64(a, b, &rem);
144}
145
146/* 32bit remainder of the signed division */
147int __modsi3(int a, int b)
148{
149 unsigned int rem;
150 divandmod32(a, b, &rem);
151
152 /* if divident is negative, remainder must be too */
153 if (!(SGN(a)))
154 return -((int) rem);
155
156 return (int) rem;
157}
158
159/* 64bit remainder of the signed division */
160long long __moddi3(long long a, long long b)
161{
162 unsigned long long rem;
163 divandmod64(a, b, &rem);
164
165 /* if divident is negative, remainder must be too */
166 if (!(SGN(a)))
167 return -((long long) rem);
168
169 return (long long) rem;
170}
171
172/* 32bit remainder of the unsigned division */
173unsigned int __umodsi3(unsigned int a, unsigned int b)
174{
175 unsigned int rem;
176 divandmod32(a, b, &rem);
177 return rem;
178}
179
180/* 64bit remainder of the unsigned division */
181unsigned long long __umoddi3(unsigned long long a, unsigned long long b)
182{
183 unsigned long long rem;
184 divandmod64(a, b, &rem);
185 return rem;
186}
187
188int __divmodsi3(int a, int b, int *c)
189{
190 unsigned int rem;
191 int result = (int) divandmod32(ABSVAL(a), ABSVAL(b), &rem);
192
193 if (SGN(a) == SGN(b)) {
194 *c = rem;
195 return result;
196 }
197
198 *c = -rem;
199 return -result;
200}
201
202unsigned int __udivmodsi3(unsigned int a, unsigned int b,
203 unsigned int *c)
204{
205 return divandmod32(a, b, c);
206}
207
208long long __divmoddi3(long long a, long long b, long long *c)
209{
210 unsigned long long rem;
211 long long result = (int) divandmod64(ABSVAL(a), ABSVAL(b), &rem);
212
213 if (SGN(a) == SGN(b)) {
214 *c = rem;
215 return result;
216 }
217
218 *c = -rem;
219 return -result;
220}
221
222unsigned long long __udivmoddi3(unsigned long long a, unsigned long long b,
223 unsigned long long *c)
224{
225 return divandmod64(a, b, c);
226}
227
228unsigned long long __udivmoddi4(unsigned long long a, unsigned long long b,
229 unsigned long long *c)
230{
231 return divandmod64(a, b, c);
232}
233
234/** @}
235 */
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