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| Rev | Author | Line No. | Line |
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| 991 | cejka | 1 | /* |
| 2 | * Copyright (C) 2006 Josef Cejka |
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| 3 | * All rights reserved. |
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| 4 | * |
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| 5 | * Redistribution and use in source and binary forms, with or without |
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| 6 | * modification, are permitted provided that the following conditions |
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| 7 | * are met: |
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| 8 | * |
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| 9 | * - Redistributions of source code must retain the above copyright |
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| 10 | * notice, this list of conditions and the following disclaimer. |
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| 11 | * - Redistributions in binary form must reproduce the above copyright |
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| 12 | * notice, this list of conditions and the following disclaimer in the |
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| 13 | * documentation and/or other materials provided with the distribution. |
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| 14 | * - The name of the author may not be used to endorse or promote products |
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| 15 | * derived from this software without specific prior written permission. |
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| 16 | * |
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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| 27 | */ |
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| 28 | |||
| 1740 | jermar | 29 | /** @addtogroup softint |
| 1653 | cejka | 30 | * @{ |
| 31 | */ |
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| 32 | /** |
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| 33 | * @file |
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| 34 | * SW implementation of 32 and 64 bit division and modulo. |
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| 35 | */ |
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| 36 | |||
| 991 | cejka | 37 | #include <division.h> |
| 38 | |||
| 39 | #define ABSVAL(x) ( (x) > 0 ? (x) : -(x)) |
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| 40 | #define SGN(x) ( (x) >= 0 ? 1 : 0 ) |
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| 41 | |||
| 42 | static unsigned int divandmod32(unsigned int a, unsigned int b, unsigned int *remainder) |
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| 43 | { |
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| 44 | unsigned int result; |
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| 45 | int steps = sizeof(unsigned int) * 8; |
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| 46 | |||
| 47 | *remainder = 0; |
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| 48 | result = 0; |
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| 49 | |||
| 50 | if (b == 0) { |
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| 51 | /* FIXME: division by zero */ |
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| 52 | return 0; |
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| 53 | } |
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| 54 | |||
| 55 | if ( a < b) { |
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| 56 | *remainder = a; |
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| 57 | return 0; |
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| 58 | } |
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| 59 | |||
| 60 | for ( ; steps > 0; steps--) { |
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| 61 | /* shift one bit to remainder */ |
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| 62 | *remainder = ( (*remainder) << 1) | (( a >> 31) & 0x1); |
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| 63 | result <<= 1; |
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| 64 | |||
| 65 | if (*remainder >= b) { |
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| 66 | *remainder -= b; |
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| 67 | result |= 0x1; |
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| 68 | } |
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| 69 | a <<= 1; |
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| 70 | } |
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| 71 | |||
| 72 | return result; |
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| 73 | } |
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| 74 | |||
| 75 | |||
| 76 | static unsigned long long divandmod64(unsigned long long a, unsigned long long b, unsigned long long *remainder) |
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| 77 | { |
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| 78 | unsigned long long result; |
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| 79 | int steps = sizeof(unsigned long long) * 8; |
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| 80 | |||
| 81 | *remainder = 0; |
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| 82 | result = 0; |
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| 83 | |||
| 84 | if (b == 0) { |
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| 85 | /* FIXME: division by zero */ |
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| 86 | return 0; |
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| 87 | } |
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| 88 | |||
| 89 | if ( a < b) { |
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| 90 | *remainder = a; |
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| 91 | return 0; |
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| 92 | } |
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| 93 | |||
| 94 | for ( ; steps > 0; steps--) { |
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| 95 | /* shift one bit to remainder */ |
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| 96 | *remainder = ( (*remainder) << 1) | ((a >> 63) & 0x1); |
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| 97 | result <<= 1; |
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| 98 | |||
| 99 | if (*remainder >= b) { |
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| 100 | *remainder -= b; |
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| 101 | result |= 0x1; |
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| 102 | } |
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| 103 | a <<= 1; |
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| 104 | } |
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| 105 | |||
| 106 | return result; |
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| 107 | } |
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| 108 | |||
| 109 | /* 32bit integer division */ |
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| 110 | int __divsi3(int a, int b) |
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| 111 | { |
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| 112 | unsigned int rem; |
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| 113 | int result; |
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| 114 | |||
| 115 | result = (int)divandmod32(ABSVAL(a), ABSVAL(b), &rem); |
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| 116 | |||
| 117 | if ( SGN(a) == SGN(b)) return result; |
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| 118 | return -result; |
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| 119 | } |
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| 120 | |||
| 121 | /* 64bit integer division */ |
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| 122 | long long __divdi3(long long a, long long b) |
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| 123 | { |
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| 124 | unsigned long long rem; |
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| 125 | long long result; |
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| 126 | |||
| 127 | result = (long long)divandmod64(ABSVAL(a), ABSVAL(b), &rem); |
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| 128 | |||
| 129 | if ( SGN(a) == SGN(b)) return result; |
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| 130 | return -result; |
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| 131 | } |
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| 132 | |||
| 133 | /* 32bit unsigned integer division */ |
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| 134 | unsigned int __udivsi3(unsigned int a, unsigned int b) |
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| 135 | { |
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| 136 | unsigned int rem; |
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| 137 | return divandmod32(a, b, &rem); |
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| 138 | } |
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| 139 | |||
| 140 | /* 64bit unsigned integer division */ |
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| 141 | unsigned long long __udivdi3(unsigned long long a, unsigned long long b) |
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| 142 | { |
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| 143 | unsigned long long rem; |
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| 144 | return divandmod64(a, b, &rem); |
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| 145 | } |
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| 146 | |||
| 147 | /* 32bit remainder of the signed division */ |
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| 148 | int __modsi3(int a, int b) |
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| 149 | { |
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| 150 | unsigned int rem; |
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| 151 | divandmod32(a, b, &rem); |
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| 152 | |||
| 153 | /* if divident is negative, remainder must be too */ |
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| 154 | if (!(SGN(a))) { |
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| 155 | return -((int)rem); |
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| 156 | } |
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| 157 | |||
| 158 | return (int)rem; |
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| 159 | } |
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| 160 | |||
| 161 | /* 64bit remainder of the signed division */ |
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| 162 | long long __moddi3(long long a,long long b) |
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| 163 | { |
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| 164 | unsigned long long rem; |
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| 165 | divandmod64(a, b, &rem); |
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| 166 | |||
| 167 | /* if divident is negative, remainder must be too */ |
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| 168 | if (!(SGN(a))) { |
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| 169 | return -((long long)rem); |
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| 170 | } |
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| 171 | |||
| 172 | return (long long)rem; |
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| 173 | } |
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| 174 | |||
| 175 | /* 32bit remainder of the unsigned division */ |
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| 176 | unsigned int __umodsi3(unsigned int a, unsigned int b) |
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| 177 | { |
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| 178 | unsigned int rem; |
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| 179 | divandmod32(a, b, &rem); |
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| 180 | return rem; |
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| 181 | } |
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| 182 | |||
| 183 | /* 64bit remainder of the unsigned division */ |
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| 184 | unsigned long long __umoddi3(unsigned long long a, unsigned long long b) |
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| 185 | { |
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| 186 | unsigned long long rem; |
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| 187 | divandmod64(a, b, &rem); |
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| 188 | return rem; |
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| 189 | } |
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| 190 | |||
| 191 | unsigned long long __udivmoddi3(unsigned long long a, unsigned long long b, unsigned long long *c) |
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| 192 | { |
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| 193 | return divandmod64(a, b, c); |
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| 194 | } |
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| 195 | |||
| 1653 | cejka | 196 | /** @} |
| 197 | */ |