Move SaturatedArithmetic from Blink to base

third_party/WebKit/Source/wtf/asm/SaturatedArithmeticARM.h

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef SaturatedArithmeticARM_h
-#define SaturatedArithmeticARM_h
-
-#include "wtf/CPU.h"
-#include <limits>
-#include <stdint.h>
-
-ALWAYS_INLINE int32_t saturatedAddition(int32_t a, int32_t b) {
-  int32_t result;
-
-  asm("qadd %[output],%[first],%[second]"
-      : [output] "=r"(result)
-      : [first] "r"(a), [second] "r"(b));
-
-  return result;
-}
-
-ALWAYS_INLINE int32_t saturatedSubtraction(int32_t a, int32_t b) {
-  int32_t result;
-
-  asm("qsub %[output],%[first],%[second]"
-      : [output] "=r"(result)
-      : [first] "r"(a), [second] "r"(b));
-
-  return result;
-}
-
-ALWAYS_INLINE int32_t saturatedNegative(int32_t a) {
-  return saturatedSubtraction(0, a);
-}
-
-inline int getMaxSaturatedSetResultForTesting(int FractionalShift) {
-  // For ARM Asm version the set function maxes out to the biggest
-  // possible integer part with the fractional part zero'd out.
-  // e.g. 0x7fffffc0.
-  return std::numeric_limits<int>::max() & ~((1 << FractionalShift) - 1);
-}
-
-inline int getMinSaturatedSetResultForTesting(int FractionalShift) {
-  return std::numeric_limits<int>::min();
-}
-
-template <int FractionalShift>
-ALWAYS_INLINE int saturatedSet(int value) {
-  // Figure out how many bits are left for storing the integer part of
-  // the fixed point number, and saturate our input to that
-  enum { Saturate = 32 - FractionalShift };
-
-  int result;
-
-  // The following ARM code will Saturate the passed value to the number of
-  // bits used for the whole part of the fixed point representation, then
-  // shift it up into place. This will result in the low <FractionShift> bits
-  // all being 0's. When the value saturates this gives a different result
-  // to from the C++ case; in the C++ code a saturated value has all the low
-  // bits set to 1 (for a +ve number at least). This cannot be done rapidly
-  // in ARM ... we live with the difference, for the sake of speed.
-
-  asm("ssat %[output],%[saturate],%[value]\n\t"
-      "lsl  %[output],%[shift]"
-      : [output] "=r"(result)
-      : [value] "r"(value), [saturate] "n"(Saturate),
-        [shift] "n"(FractionalShift));
-
-  return result;
-}
-
-template <int FractionalShift>
-ALWAYS_INLINE int saturatedSet(unsigned value) {
-  // Here we are being passed an unsigned value to saturate,
-  // even though the result is returned as a signed integer. The ARM
-  // instruction for unsigned saturation therefore needs to be given one
-  // less bit (i.e. the sign bit) for the saturation to work correctly; hence
-  // the '31' below.
-  enum { Saturate = 31 - FractionalShift };
-
-  // The following ARM code will Saturate the passed value to the number of
-  // bits used for the whole part of the fixed point representation, then
-  // shift it up into place. This will result in the low <FractionShift> bits
-  // all being 0's. When the value saturates this gives a different result
-  // to from the C++ case; in the C++ code a saturated value has all the low
-  // bits set to 1. This cannot be done rapidly in ARM, so we live with the
-  // difference, for the sake of speed.
-
-  int result;
-
-  asm("usat %[output],%[saturate],%[value]\n\t"
-      "lsl  %[output],%[shift]"
-      : [output] "=r"(result)
-      : [value] "r"(value), [saturate] "n"(Saturate),
-        [shift] "n"(FractionalShift));
-
-  return result;
-}
-
-#endif  // SaturatedArithmeticARM_h