diff -r 000000000000 -r 6474c204b198 gfx/skia/trunk/src/utils/SkFloatUtils.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/skia/trunk/src/utils/SkFloatUtils.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,173 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkFloatUtils_DEFINED
+#define SkFloatUtils_DEFINED
+
+#include "SkTypes.h"
+#include <limits.h>
+#include <float.h>
+
+template <size_t size>
+class SkTypeWithSize {
+public:
+    // Prevents using SkTypeWithSize<N> with non-specialized N.
+    typedef void UInt;
+};
+
+template <>
+class SkTypeWithSize<32> {
+public:
+    typedef uint32_t UInt;
+};
+
+template <>
+class SkTypeWithSize<64> {
+public:
+    typedef uint64_t UInt;
+};
+
+template <typename RawType>
+struct SkNumericLimits {
+    static const int digits = 0;
+};
+
+template <>
+struct SkNumericLimits<double> {
+    static const int digits = DBL_MANT_DIG;
+};
+
+template <>
+struct SkNumericLimits<float> {
+    static const int digits = FLT_MANT_DIG;
+};
+
+//See
+//http://stackoverflow.com/questions/17333/most-effective-way-for-float-and-double-comparison/3423299#3423299
+//http://code.google.com/p/googletest/source/browse/trunk/include/gtest/internal/gtest-internal.h
+//http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm
+
+template <typename RawType, unsigned int ULPs>
+class SkFloatingPoint {
+public:
+    /** Bits is a unsigned integer the same size as the floating point number. */
+    typedef typename SkTypeWithSize<sizeof(RawType) * CHAR_BIT>::UInt Bits;
+
+    /** # of bits in a number. */
+    static const size_t kBitCount = CHAR_BIT * sizeof(RawType);
+
+    /** # of fraction bits in a number. */
+    static const size_t kFractionBitCount = SkNumericLimits<RawType>::digits - 1;
+
+    /** # of exponent bits in a number. */
+    static const size_t kExponentBitCount = kBitCount - 1 - kFractionBitCount;
+
+    /** The mask for the sign bit. */
+    static const Bits kSignBitMask = static_cast<Bits>(1) << (kBitCount - 1);
+
+    /** The mask for the fraction bits. */
+    static const Bits kFractionBitMask =
+        ~static_cast<Bits>(0) >> (kExponentBitCount + 1);
+
+    /** The mask for the exponent bits. */
+    static const Bits kExponentBitMask = ~(kSignBitMask | kFractionBitMask);
+
+    /** How many ULP's (Units in the Last Place) to tolerate when comparing. */
+    static const size_t kMaxUlps = ULPs;
+
+    /**
+     *  Constructs a FloatingPoint from a raw floating-point number.
+     *
+     *  On an Intel CPU, passing a non-normalized NAN (Not a Number)
+     *  around may change its bits, although the new value is guaranteed
+     *  to be also a NAN.  Therefore, don't expect this constructor to
+     *  preserve the bits in x when x is a NAN.
+     */
+    explicit SkFloatingPoint(const RawType& x) { fU.value = x; }
+
+    /** Returns the exponent bits of this number. */
+    Bits exponent_bits() const { return kExponentBitMask & fU.bits; }
+
+    /** Returns the fraction bits of this number. */
+    Bits fraction_bits() const { return kFractionBitMask & fU.bits; }
+
+    /** Returns true iff this is NAN (not a number). */
+    bool is_nan() const {
+        // It's a NAN if both of the folloowing are true:
+        // * the exponent bits are all ones
+        // * the fraction bits are not all zero.
+        return (exponent_bits() == kExponentBitMask) && (fraction_bits() != 0);
+    }
+
+    /**
+     *  Returns true iff this number is at most kMaxUlps ULP's away from ths.
+     *  In particular, this function:
+     *   - returns false if either number is (or both are) NAN.
+     *   - treats really large numbers as almost equal to infinity.
+     *   - thinks +0.0 and -0.0 are 0 DLP's apart.
+     */
+    bool AlmostEquals(const SkFloatingPoint& rhs) const {
+        // Any comparison operation involving a NAN must return false.
+        if (is_nan() || rhs.is_nan()) return false;
+
+        const Bits dist = DistanceBetweenSignAndMagnitudeNumbers(fU.bits,
+                                                                 rhs.fU.bits);
+        //SkDEBUGF(("(%f, %f, %d) ", u_.value_, rhs.u_.value_, dist));
+        return dist <= kMaxUlps;
+    }
+
+private:
+    /** The data type used to store the actual floating-point number. */
+    union FloatingPointUnion {
+        /** The raw floating-point number. */
+        RawType value;
+        /** The bits that represent the number. */
+        Bits bits;
+    };
+
+    /**
+     *  Converts an integer from the sign-and-magnitude representation to
+     *  the biased representation. More precisely, let N be 2 to the
+     *  power of (kBitCount - 1), an integer x is represented by the
+     *  unsigned number x + N.
+     *
+     *  For instance,
+     *
+     *    -N + 1 (the most negative number representable using
+     *           sign-and-magnitude) is represented by 1;
+     *    0      is represented by N; and
+     *    N - 1  (the biggest number representable using
+     *           sign-and-magnitude) is represented by 2N - 1.
+     *
+     *  Read http://en.wikipedia.org/wiki/Signed_number_representations
+     *  for more details on signed number representations.
+     */
+    static Bits SignAndMagnitudeToBiased(const Bits &sam) {
+        if (kSignBitMask & sam) {
+            // sam represents a negative number.
+            return ~sam + 1;
+        } else {
+            // sam represents a positive number.
+            return kSignBitMask | sam;
+        }
+    }
+
+    /**
+     *  Given two numbers in the sign-and-magnitude representation,
+     *  returns the distance between them as an unsigned number.
+     */
+    static Bits DistanceBetweenSignAndMagnitudeNumbers(const Bits &sam1,
+                                                       const Bits &sam2) {
+        const Bits biased1 = SignAndMagnitudeToBiased(sam1);
+        const Bits biased2 = SignAndMagnitudeToBiased(sam2);
+        return (biased1 >= biased2) ? (biased1 - biased2) : (biased2 - biased1);
+    }
+
+    FloatingPointUnion fU;
+};
+
+#endif