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/*
* Copyright (c) 2012, Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef SaturatedArithmetic_h
#define SaturatedArithmetic_h
#include <limits>
#include <stdint.h>
#include <stdlib.h>
inline int32_t saturatedAddition(int32_t a, int32_t b)
{
uint32_t ua = a;
uint32_t ub = b;
uint32_t result = ua + ub;
// Can only overflow if the signed bit of the two values match. If the signed
// bit of the result and one of the values differ it did overflow.
if (!((ua ^ ub) >> 31) & (result ^ ua) >> 31)
result = std::numeric_limits<int>::max() + (ua >> 31);
return result;
}
inline int32_t saturatedSubtraction(int32_t a, int32_t b)
{
uint32_t ua = a;
uint32_t ub = b;
uint32_t result = ua - ub;
// Can only overflow if the signed bit of the two values do not match. If the
// signed bit of the result and the first value differ it did overflow.
if ((ua ^ ub) >> 31 & (result ^ ua) >> 31)
result = std::numeric_limits<int>::max() + (ua >> 31);
return result;
}
#endif // SaturatedArithmetic_h
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