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