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| 1 /* | |
| 2 * Copyright (c) 2012, Google Inc. All rights reserved. | |
| 3 * | |
| 4 * Redistribution and use in source and binary forms, with or without | |
| 5 * modification, are permitted provided that the following conditions are | |
| 6 * met: | |
| 7 * | |
| 8 * * Redistributions of source code must retain the above copyright | |
| 9 * notice, this list of conditions and the following disclaimer. | |
| 10 * * Redistributions in binary form must reproduce the above | |
| 11 * copyright notice, this list of conditions and the following disclaimer | |
| 12 * in the documentation and/or other materials provided with the | |
| 13 * distribution. | |
| 14 * * Neither the name of Google Inc. nor the names of its | |
| 15 * contributors may be used to endorse or promote products derived from | |
| 16 * this software without specific prior written permission. | |
| 17 * | |
| 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
| 21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
| 22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| 23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
| 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
| 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 29 */ | |
| 30 | |
| 31 #ifndef SaturatedArithmetic_h | |
| 32 #define SaturatedArithmetic_h | |
| 33 | |
| 34 #include <limits> | |
| 35 #include <stdint.h> | |
| 36 #include <stdlib.h> | |
| 37 | |
| 38 inline int32_t saturatedAddition(int32_t a, int32_t b) | |
| 39 { | |
| 40 uint32_t ua = a; | |
| 41 uint32_t ub = b; | |
| 42 uint32_t result = ua + ub; | |
| 43 | |
| 44 // Can only overflow if the signed bit of the two values match. If the signe
d | |
| 45 // bit of the result and one of the values differ it did overflow. | |
| 46 if (!((ua ^ ub) >> 31) & (result ^ ua) >> 31) | |
| 47 result = std::numeric_limits<int>::max() + (ua >> 31); | |
| 48 | |
| 49 return result; | |
| 50 } | |
| 51 | |
| 52 inline int32_t saturatedSubtraction(int32_t a, int32_t b) | |
| 53 { | |
| 54 uint32_t ua = a; | |
| 55 uint32_t ub = b; | |
| 56 uint32_t result = ua - ub; | |
| 57 | |
| 58 // Can only overflow if the signed bit of the two values do not match. If th
e | |
| 59 // signed bit of the result and the first value differ it did overflow. | |
| 60 if ((ua ^ ub) >> 31 & (result ^ ua) >> 31) | |
| 61 result = std::numeric_limits<int>::max() + (ua >> 31); | |
| 62 | |
| 63 return result; | |
| 64 } | |
| 65 | |
| 66 #endif // SaturatedArithmetic_h | |
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Chromium Code Reviews
Issue 14238015:
Move Source/WTF/wtf to Source/wtf (Closed)
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