Add Chromium-only Blender WebEngine parity work

blender-5.2.0/extern/mantaflow/helper/util/randomstream.h

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+/******************************************************************************
+ *
+ * MantaFlow fluid solver framework
+ * Copyright 2011 Tobias Pfaff, Nils Thuerey
+ *
+ * This program is free software, distributed under the terms of the
+ * Apache License, Version 2.0
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Random numbers
+ *
+ * Based on an example by Makoto Matsumoto, Takuji Nishimura, Shawn Cokus, and Richard J. Wagner
+ *
+ ******************************************************************************/
+
+#ifndef _RANDOMSTREAM_H
+#define _RANDOMSTREAM_H
+
+#include <iostream>
+#include <stdio.h>
+#include <time.h>
+#include "vectorbase.h"
+
+namespace Manta {
+
+class MTRand {
+  // Data
+ public:
+  typedef unsigned long uint32;  // unsigned integer type, at least 32 bits
+
+  static constexpr int  N = 624;       // length of state vector
+  static constexpr int SAVE = N + 1;   // length of array for save()
+
+ protected:
+  static constexpr int  M = 397;  // period parameter
+
+  uint32 state[N];  // internal state
+  uint32 *pNext;    // next value to get from state
+  int left;         // number of values left before reload needed
+
+  // Methods
+ public:
+  MTRand(const uint32 &oneSeed);                               // initialize with a simple uint32
+  MTRand(uint32 *const bigSeed, uint32 const seedLength = N);  // or an array
+  MTRand();  // auto-initialize with /dev/urandom or time() and clock()
+
+  // Do NOT use for CRYPTOGRAPHY without securely hashing several returned
+  // values together, otherwise the generator state can be learned after
+  // reading 624 consecutive values.
+
+  // Access to 32-bit random numbers
+  double rand();                       // real number in [0,1]
+  double rand(const double &n);        // real number in [0,n]
+  double randExc();                    // real number in [0,1)
+  double randExc(const double &n);     // real number in [0,n)
+  double randDblExc();                 // real number in (0,1)
+  double randDblExc(const double &n);  // real number in (0,n)
+  uint32 randInt();                    // integer in [0,2^32-1]
+  uint32 randInt(const uint32 &n);     // integer in [0,n] for n < 2^32
+  double operator()()
+  {
+    return rand();
+  }  // same as rand()
+
+  // Access to 53-bit random numbers (capacity of IEEE double precision)
+  double rand53();  // real number in [0,1)
+
+  // Access to nonuniform random number distributions
+  double randNorm(const double &mean = 0.0, const double &variance = 1.0);
+
+  // Re-seeding functions with same behavior as initializers
+  void seed(const uint32 oneSeed);
+  void seed(uint32 *const bigSeed, const uint32 seedLength = N);
+  void seed();
+
+  // Saving and loading generator state
+  void save(uint32 *saveArray) const;  // to array of size SAVE
+  void load(uint32 *const loadArray);  // from such array
+  friend std::ostream &operator<<(std::ostream &os, const MTRand &mtrand);
+  friend std::istream &operator>>(std::istream &is, MTRand &mtrand);
+
+ protected:
+  void initialize(const uint32 oneSeed);
+  void reload();
+  uint32 hiBit(const uint32 &u) const
+  {
+    return u & 0x80000000UL;
+  }
+  uint32 loBit(const uint32 &u) const
+  {
+    return u & 0x00000001UL;
+  }
+  uint32 loBits(const uint32 &u) const
+  {
+    return u & 0x7fffffffUL;
+  }
+  uint32 mixBits(const uint32 &u, const uint32 &v) const
+  {
+    return hiBit(u) | loBits(v);
+  }
+  uint32 twist(const uint32 &m, const uint32 &s0, const uint32 &s1) const
+  {
+    return m ^ (mixBits(s0, s1) >> 1) ^ (-loBit(s1) & 0x9908b0dfUL);
+  }
+  static uint32 hash(time_t t, clock_t c);
+};
+
+inline MTRand::MTRand(const uint32 &oneSeed)
+{
+  seed(oneSeed);
+}
+
+inline MTRand::MTRand(uint32 *const bigSeed, const uint32 seedLength)
+{
+  seed(bigSeed, seedLength);
+}
+
+inline MTRand::MTRand()
+{
+  seed();
+}
+
+inline double MTRand::rand()
+{
+  return double(randInt()) * (1.0 / 4294967295.0);
+}
+
+inline double MTRand::rand(const double &n)
+{
+  return rand() * n;
+}
+
+inline double MTRand::randExc()
+{
+  return double(randInt()) * (1.0 / 4294967296.0);
+}
+
+inline double MTRand::randExc(const double &n)
+{
+  return randExc() * n;
+}
+
+inline double MTRand::randDblExc()
+{
+  return (double(randInt()) + 0.5) * (1.0 / 4294967296.0);
+}
+
+inline double MTRand::randDblExc(const double &n)
+{
+  return randDblExc() * n;
+}
+
+inline double MTRand::rand53()
+{
+  uint32 a = randInt() >> 5, b = randInt() >> 6;
+  return (a * 67108864.0 + b) * (1.0 / 9007199254740992.0);  // by Isaku Wada
+}
+
+inline double MTRand::randNorm(const double &mean, const double &variance)
+{
+  // Return a real number from a normal (Gaussian) distribution with given
+  // mean and variance by Box-Muller method
+  double r = sqrt(-2.0 * log(1.0 - randDblExc())) * variance;
+  double phi = 2.0 * 3.14159265358979323846264338328 * randExc();
+  return mean + r * cos(phi);
+}
+
+inline MTRand::uint32 MTRand::randInt()
+{
+  // Pull a 32-bit integer from the generator state
+  // Every other access function simply transforms the numbers extracted here
+
+  if (left == 0)
+    reload();
+  --left;
+
+  uint32 s1;
+  s1 = *pNext++;
+  s1 ^= (s1 >> 11);
+  s1 ^= (s1 << 7) & 0x9d2c5680UL;
+  s1 ^= (s1 << 15) & 0xefc60000UL;
+  return (s1 ^ (s1 >> 18));
+}
+
+inline MTRand::uint32 MTRand::randInt(const uint32 &n)
+{
+  // Find which bits are used in n
+  // Optimized by Magnus Jonsson (magnus@smartelectronix.com)
+  uint32 used = n;
+  used |= used >> 1;
+  used |= used >> 2;
+  used |= used >> 4;
+  used |= used >> 8;
+  used |= used >> 16;
+
+  // Draw numbers until one is found in [0,n]
+  uint32 i;
+  do
+    i = randInt() & used;  // toss unused bits to shorten search
+  while (i > n);
+  return i;
+}
+
+inline void MTRand::seed(const uint32 oneSeed)
+{
+  // Seed the generator with a simple uint32
+  initialize(oneSeed);
+  reload();
+}
+
+inline void MTRand::seed(uint32 *const bigSeed, const uint32 seedLength)
+{
+  // Seed the generator with an array of uint32's
+  // There are 2^19937-1 possible initial states.  This function allows
+  // all of those to be accessed by providing at least 19937 bits (with a
+  // default seed length of N = 624 uint32's).  Any bits above the lower 32
+  // in each element are discarded.
+  // Just call seed() if you want to get array from /dev/urandom
+  initialize(19650218UL);
+  const unsigned int Nenum = N;
+  int i = 1;
+  uint32 j = 0;
+  int k = (Nenum > seedLength ? Nenum : seedLength);
+  for (; k; --k) {
+    state[i] = state[i] ^ ((state[i - 1] ^ (state[i - 1] >> 30)) * 1664525UL);
+    state[i] += (bigSeed[j] & 0xffffffffUL) + j;
+    state[i] &= 0xffffffffUL;
+    ++i;
+    ++j;
+    if (i >= N) {
+      state[0] = state[N - 1];
+      i = 1;
+    }
+    if (j >= seedLength)
+      j = 0;
+  }
+  for (k = N - 1; k; --k) {
+    state[i] = state[i] ^ ((state[i - 1] ^ (state[i - 1] >> 30)) * 1566083941UL);
+    state[i] -= i;
+    state[i] &= 0xffffffffUL;
+    ++i;
+    if (i >= N) {
+      state[0] = state[N - 1];
+      i = 1;
+    }
+  }
+  state[0] = 0x80000000UL;  // MSB is 1, assuring non-zero initial array
+  reload();
+}
+
+inline void MTRand::seed()
+{
+  // Seed the generator with an array from /dev/urandom if available
+  // Otherwise use a hash of time() and clock() values
+
+  // First try getting an array from /dev/urandom
+  FILE *urandom = fopen("/dev/urandom", "rb");
+  if (urandom) {
+    uint32 bigSeed[N];
+    uint32 *s = bigSeed;
+    int i = N;
+    bool success = true;
+    while (success && i--)
+      success = fread(s++, sizeof(uint32), 1, urandom);
+    fclose(urandom);
+    if (success) {
+      seed(bigSeed, N);
+      return;
+    }
+  }
+
+  // Was not successful, so use time() and clock() instead
+  seed(hash(time(nullptr), clock()));
+}
+
+inline void MTRand::initialize(const uint32 intseed)
+{
+  // Initialize generator state with seed
+  // See Knuth TAOCP Vol 2, 3rd Ed, p.106 for multiplier.
+  // In previous versions, most significant bits (MSBs) of the seed affect
+  // only MSBs of the state array.  Modified 9 Jan 2002 by Makoto Matsumoto.
+  uint32 *s = state;
+  uint32 *r = state;
+  int i = 1;
+  *s++ = intseed & 0xffffffffUL;
+  for (; i < N; ++i) {
+    *s++ = (1812433253UL * (*r ^ (*r >> 30)) + i) & 0xffffffffUL;
+    r++;
+  }
+}
+
+inline void MTRand::reload()
+{
+  // Generate N new values in state
+  // Made clearer and faster by Matthew Bellew (matthew.bellew@home.com)
+  uint32 *p = state;
+  int i;
+  for (i = N - M; i--; ++p)
+    *p = twist(p[M], p[0], p[1]);
+  for (i = M; --i; ++p)
+    *p = twist(p[M - N], p[0], p[1]);
+  *p = twist(p[M - N], p[0], state[0]);
+
+  left = N, pNext = state;
+}
+
+inline MTRand::uint32 MTRand::hash(time_t t, clock_t c)
+{
+  // Get a uint32 from t and c
+  // Better than uint32(x) in case x is floating point in [0,1]
+  // Based on code by Lawrence Kirby (fred@genesis.demon.co.uk)
+
+  static uint32 differ = 0;  // guarantee time-based seeds will change
+
+  uint32 h1 = 0;
+  unsigned char *p = (unsigned char *)&t;
+  for (size_t i = 0; i < sizeof(t); ++i) {
+    h1 *= std::numeric_limits<unsigned char>::max() + 2U;
+    h1 += p[i];
+  }
+  uint32 h2 = 0;
+  p = (unsigned char *)&c;
+  for (size_t j = 0; j < sizeof(c); ++j) {
+    h2 *= std::numeric_limits<unsigned char>::max() + 2U;
+    h2 += p[j];
+  }
+  return (h1 + differ++) ^ h2;
+}
+
+inline void MTRand::save(uint32 *saveArray) const
+{
+  uint32 *sa = saveArray;
+  const uint32 *s = state;
+  int i = N;
+  for (; i--; *sa++ = *s++) {
+  }
+  *sa = left;
+}
+
+inline void MTRand::load(uint32 *const loadArray)
+{
+  uint32 *s = state;
+  uint32 *la = loadArray;
+  int i = N;
+  for (; i--; *s++ = *la++) {
+  }
+  left = *la;
+  pNext = &state[N - left];
+}
+
+inline std::ostream &operator<<(std::ostream &os, const MTRand &mtrand)
+{
+  const MTRand::uint32 *s = mtrand.state;
+  int i = mtrand.N;
+  for (; i--; os << *s++ << "\t") {
+  }
+  return os << mtrand.left;
+}
+
+inline std::istream &operator>>(std::istream &is, MTRand &mtrand)
+{
+  MTRand::uint32 *s = mtrand.state;
+  int i = mtrand.N;
+  for (; i--; is >> *s++) {
+  }
+  is >> mtrand.left;
+  mtrand.pNext = &mtrand.state[mtrand.N - mtrand.left];
+  return is;
+}
+
+// simple interface to mersenne twister
+class RandomStream {
+ public:
+  inline RandomStream(long seed) : mtr(seed){};
+  ~RandomStream()
+  {
+  }
+
+  /*! get a random number from the stream */
+  inline float getRandNorm(float mean, float var)
+  {
+    return mtr.randNorm(mean, var);
+  };
+
+#if FLOATINGPOINT_PRECISION == 1
+  inline Real getReal()
+  {
+    return getFloat();
+  }
+  inline Real getReal(float min, float max)
+  {
+    return getFloat(min, max);
+  }
+
+#else
+  inline Real getReal()
+  {
+    return getDouble();
+  }
+  inline Real getReal(double min, double max)
+  {
+    return getDouble(min, max);
+  }
+#endif
+
+  inline Vec3 getVec3()
+  {
+    Real a = getReal(), b = getReal(), c = getReal();
+    return Vec3(a, b, c);
+  }
+  inline Vec3 getVec3Norm()
+  {
+    Vec3 a = getVec3();
+    normalize(a);
+    return a;
+  }
+
+ private:
+  MTRand mtr;
+
+  inline double getDouble(void)
+  {
+    return mtr.rand();
+  };
+  inline float getFloat(void)
+  {
+    return (float)mtr.rand();
+  };
+
+  inline double getDouble(double min, double max)
+  {
+    return mtr.rand(max - min) + min;
+  };
+  inline float getFloat(float min, float max)
+  {
+    return (float)(mtr.rand(max - min) + min);
+  };
+};
+
+}  // namespace Manta
+
+#endif