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113 lines
3.9 KiB
C++
113 lines
3.9 KiB
C++
/*
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* Copyright (c) 2012, Google Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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* * Neither the name of Google Inc. nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef SKY_ENGINE_WTF_SATURATEDARITHMETIC_H_
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#define SKY_ENGINE_WTF_SATURATEDARITHMETIC_H_
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#include <stdint.h>
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#include <limits>
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#include "flutter/sky/engine/wtf/CPU.h"
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#if CPU(ARM) && COMPILER(GCC) && __OPTIMIZE__
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// If we're building ARM on GCC we replace the C++ versions with some
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// native ARM assembly for speed.
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#include "flutter/sky/engine/wtf/asm/SaturatedArithmeticARM.h"
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#else
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ALWAYS_INLINE int32_t saturatedAddition(int32_t a, int32_t b) {
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uint32_t ua = a;
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uint32_t ub = b;
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uint32_t result = ua + ub;
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// Can only overflow if the signed bit of the two values match. If the
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// signed bit of the result and one of the values differ it overflowed.
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if (~(ua ^ ub) & (result ^ ua) & (1 << 31))
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return std::numeric_limits<int>::max() + (ua >> 31);
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return result;
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}
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ALWAYS_INLINE int32_t saturatedSubtraction(int32_t a, int32_t b) {
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uint32_t ua = a;
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uint32_t ub = b;
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uint32_t result = ua - ub;
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// Can only overflow if the signed bit of the two input values differ. If
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// the signed bit of the result and the first value differ it overflowed.
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if ((ua ^ ub) & (result ^ ua) & (1 << 31))
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return std::numeric_limits<int>::max() + (ua >> 31);
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return result;
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}
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inline int getMaxSaturatedSetResultForTesting(int FractionalShift) {
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// For C version the set function maxes out to max int, this differs from
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// the ARM asm version, see SaturatedArithmetiARM.h for the equivalent asm
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// version.
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return std::numeric_limits<int>::max();
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}
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inline int getMinSaturatedSetResultForTesting(int FractionalShift) {
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return std::numeric_limits<int>::min();
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}
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ALWAYS_INLINE int saturatedSet(int value, int FractionalShift) {
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const int intMaxForLayoutUnit =
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std::numeric_limits<int>::max() >> FractionalShift;
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const int intMinForLayoutUnit =
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std::numeric_limits<int>::min() >> FractionalShift;
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if (value > intMaxForLayoutUnit)
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return std::numeric_limits<int>::max();
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if (value < intMinForLayoutUnit)
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return std::numeric_limits<int>::min();
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return value << FractionalShift;
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}
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ALWAYS_INLINE int saturatedSet(unsigned value, int FractionalShift) {
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const unsigned intMaxForLayoutUnit =
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std::numeric_limits<int>::max() >> FractionalShift;
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if (value >= intMaxForLayoutUnit)
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return std::numeric_limits<int>::max();
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return value << FractionalShift;
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}
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#endif // CPU(ARM) && COMPILER(GCC)
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#endif // SKY_ENGINE_WTF_SATURATEDARITHMETIC_H_
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