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/*
* Copyright 2012 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "DataTypes.h"
#include <sys/types.h>
#include <stdlib.h>
#if USE_EPSILON
const double PointEpsilon = 0.000001;
const double SquaredEpsilon = PointEpsilon * PointEpsilon;
#endif
const int UlpsEpsilon = 16;
// from http://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/
union Float_t
{
Float_t(float num = 0.0f) : f(num) {}
// Portable extraction of components.
bool negative() const { return (i >> 31) != 0; }
#if 0 // unused
int32_t RawMantissa() const { return i & ((1 << 23) - 1); }
int32_t RawExponent() const { return (i >> 23) & 0xFF; }
#endif
int32_t i;
float f;
#if SK_DEBUG
struct
{ // Bitfields for exploration. Do not use in production code.
uint32_t mantissa : 23;
uint32_t exponent : 8;
uint32_t sign : 1;
} parts;
#endif
};
bool AlmostEqualUlps(float A, float B)
{
Float_t uA(A);
Float_t uB(B);
// Different signs means they do not match.
if (uA.negative() != uB.negative())
{
// Check for equality to make sure +0==-0
return A == B;
}
// Find the difference in ULPs.
int ulpsDiff = abs(uA.i - uB.i);
return ulpsDiff <= UlpsEpsilon;
}
// FIXME: obsolete, delete
#if 1
int UlpsDiff(float A, float B)
{
Float_t uA(A);
Float_t uB(B);
return abs(uA.i - uB.i);
}
#endif
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