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#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