Move SaturatedArithmetic from Blink to base

third_party/WebKit/Source/wtf/SaturatedArithmetic.h

-/*
- * 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 "wtf/CPU.h"
-#include <limits>
-#include <stdint.h>
-
-#if CPU(ARM) && COMPILER(GCC) && __OPTIMIZE__
-
-// If we're building ARM on GCC we replace the C++ versions with some
-// native ARM assembly for speed.
-#include "wtf/asm/SaturatedArithmeticARM.h"
-
-#else
-
-ALWAYS_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 overflowed.
-  // The branch compiles to a CMOVNS instruction on x86.
-  if (~(ua ^ ub) & (result ^ ua) & (1 << 31))
-    return std::numeric_limits<int>::max() + (ua >> 31);
-
-  return result;
-}
-
-ALWAYS_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 input values differ. If
-  // the signed bit of the result and the first value differ it overflowed.
-  // The branch compiles to a CMOVNS instruction on x86.
-  if ((ua ^ ub) & (result ^ ua) & (1 << 31))
-    return std::numeric_limits<int>::max() + (ua >> 31);
-
-  return result;
-}
-
-ALWAYS_INLINE int32_t saturatedNegative(int32_t a) {
-  if (UNLIKELY(a == std::numeric_limits<int>::min()))
-    return std::numeric_limits<int>::max();
-  return -a;
-}
-
-inline int getMaxSaturatedSetResultForTesting(int FractionalShift) {
-  // For C version the set function maxes out to max int, this differs from
-  // the ARM asm version, see SaturatedArithmetiARM.h for the equivalent asm
-  // version.
-  return std::numeric_limits<int>::max();
-}
-
-inline int getMinSaturatedSetResultForTesting(int FractionalShift) {
-  return std::numeric_limits<int>::min();
-}
-
-template <int FractionalShift>
-ALWAYS_INLINE int saturatedSet(int value) {
-  const int intMaxForLayoutUnit =
-      std::numeric_limits<int>::max() >> FractionalShift;
-
-  const int intMinForLayoutUnit =
-      std::numeric_limits<int>::min() >> FractionalShift;
-
-  if (value > intMaxForLayoutUnit)
-    return std::numeric_limits<int>::max();
-
-  if (value < intMinForLayoutUnit)
-    return std::numeric_limits<int>::min();
-
-  return value << FractionalShift;
-}
-
-template <int FractionalShift>
-ALWAYS_INLINE int saturatedSet(unsigned value) {
-  const unsigned intMaxForLayoutUnit =
-      std::numeric_limits<int>::max() >> FractionalShift;
-
-  if (value >= intMaxForLayoutUnit)
-    return std::numeric_limits<int>::max();
-
-  return value << FractionalShift;
-}
-
-#endif  // CPU(ARM) && COMPILER(GCC)
-#endif  // SaturatedArithmetic_h