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diff --git a/gfx/skia/skia/include/utils/SkRandom.h b/gfx/skia/skia/include/utils/SkRandom.h
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+/*
+ * Copyright 2006 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkRandom_DEFINED
+#define SkRandom_DEFINED
+
+#include "../private/SkFixed.h"
+#include "SkScalar.h"
+
+/** \class SkRandom
+
+ Utility class that implements pseudo random 32bit numbers using Marsaglia's
+ multiply-with-carry "mother of all" algorithm. Unlike rand(), this class holds
+ its own state, so that multiple instances can be used with no side-effects.
+
+ Has a large period and all bits are well-randomized.
+ */
+class SkRandom {
+public:
+ SkRandom() { init(0); }
+ SkRandom(uint32_t seed) { init(seed); }
+ SkRandom(const SkRandom& rand) : fK(rand.fK), fJ(rand.fJ) {}
+
+ SkRandom& operator=(const SkRandom& rand) {
+ fK = rand.fK;
+ fJ = rand.fJ;
+
+ return *this;
+ }
+
+ /** Return the next pseudo random number as an unsigned 32bit value.
+ */
+ uint32_t nextU() {
+ fK = kKMul*(fK & 0xffff) + (fK >> 16);
+ fJ = kJMul*(fJ & 0xffff) + (fJ >> 16);
+ return (((fK << 16) | (fK >> 16)) + fJ);
+ }
+
+ /** Return the next pseudo random number as a signed 32bit value.
+ */
+ int32_t nextS() { return (int32_t)this->nextU(); }
+
+ /** Return the next pseudo random number as an unsigned 16bit value.
+ */
+ U16CPU nextU16() { return this->nextU() >> 16; }
+
+ /** Return the next pseudo random number as a signed 16bit value.
+ */
+ S16CPU nextS16() { return this->nextS() >> 16; }
+
+ /**
+ * Returns value [0...1) as an IEEE float
+ */
+ float nextF() {
+ unsigned int floatint = 0x3f800000 | (this->nextU() >> 9);
+ float f = SkBits2Float(floatint) - 1.0f;
+ return f;
+ }
+
+ /**
+ * Returns value [min...max) as a float
+ */
+ float nextRangeF(float min, float max) {
+ return min + this->nextF() * (max - min);
+ }
+
+ /** Return the next pseudo random number, as an unsigned value of
+ at most bitCount bits.
+ @param bitCount The maximum number of bits to be returned
+ */
+ uint32_t nextBits(unsigned bitCount) {
+ SkASSERT(bitCount > 0 && bitCount <= 32);
+ return this->nextU() >> (32 - bitCount);
+ }
+
+ /** Return the next pseudo random unsigned number, mapped to lie within
+ [min, max] inclusive.
+ */
+ uint32_t nextRangeU(uint32_t min, uint32_t max) {
+ SkASSERT(min <= max);
+ uint32_t range = max - min + 1;
+ if (0 == range) {
+ return this->nextU();
+ } else {
+ return min + this->nextU() % range;
+ }
+ }
+
+ /** Return the next pseudo random unsigned number, mapped to lie within
+ [0, count).
+ */
+ uint32_t nextULessThan(uint32_t count) {
+ SkASSERT(count > 0);
+ return this->nextRangeU(0, count - 1);
+ }
+
+ /** Return the next pseudo random number expressed as a SkScalar
+ in the range [0..SK_Scalar1).
+ */
+ SkScalar nextUScalar1() { return SkFixedToScalar(this->nextUFixed1()); }
+
+ /** Return the next pseudo random number expressed as a SkScalar
+ in the range [min..max).
+ */
+ SkScalar nextRangeScalar(SkScalar min, SkScalar max) {
+ return this->nextUScalar1() * (max - min) + min;
+ }
+
+ /** Return the next pseudo random number expressed as a SkScalar
+ in the range [-SK_Scalar1..SK_Scalar1).
+ */
+ SkScalar nextSScalar1() { return SkFixedToScalar(this->nextSFixed1()); }
+
+ /** Return the next pseudo random number as a bool.
+ */
+ bool nextBool() { return this->nextU() >= 0x80000000; }
+
+ /** A biased version of nextBool().
+ */
+ bool nextBiasedBool(SkScalar fractionTrue) {
+ SkASSERT(fractionTrue >= 0 && fractionTrue <= SK_Scalar1);
+ return this->nextUScalar1() <= fractionTrue;
+ }
+
+ /**
+ * Return the next pseudo random number as a signed 64bit value.
+ */
+ int64_t next64() {
+ int64_t hi = this->nextS();
+ return (hi << 32) | this->nextU();
+ }
+
+ /** Reset the random object.
+ */
+ void setSeed(uint32_t seed) { init(seed); }
+
+private:
+ // Initialize state variables with LCG.
+ // We must ensure that both J and K are non-zero, otherwise the
+ // multiply-with-carry step will forevermore return zero.
+ void init(uint32_t seed) {
+ fK = NextLCG(seed);
+ if (0 == fK) {
+ fK = NextLCG(fK);
+ }
+ fJ = NextLCG(fK);
+ if (0 == fJ) {
+ fJ = NextLCG(fJ);
+ }
+ SkASSERT(0 != fK && 0 != fJ);
+ }
+ static uint32_t NextLCG(uint32_t seed) { return kMul*seed + kAdd; }
+
+ /** Return the next pseudo random number expressed as an unsigned SkFixed
+ in the range [0..SK_Fixed1).
+ */
+ SkFixed nextUFixed1() { return this->nextU() >> 16; }
+
+ /** Return the next pseudo random number expressed as a signed SkFixed
+ in the range [-SK_Fixed1..SK_Fixed1).
+ */
+ SkFixed nextSFixed1() { return this->nextS() >> 15; }
+
+ // See "Numerical Recipes in C", 1992 page 284 for these constants
+ // For the LCG that sets the initial state from a seed
+ enum {
+ kMul = 1664525,
+ kAdd = 1013904223
+ };
+ // Constants for the multiply-with-carry steps
+ enum {
+ kKMul = 30345,
+ kJMul = 18000,
+ };
+
+ uint32_t fK;
+ uint32_t fJ;
+};
+
+#endif