1 files changed, 216 insertions, 0 deletions
diff --git a/source/core/StarRandom.hpp b/source/core/StarRandom.hpp
new file mode 100644
index 0000000..b3c8ba2
--- /dev/null
+++ b/source/core/StarRandom.hpp
@@ -0,0 +1,216 @@
+#ifndef STAR_RANDOM_HPP
+#define STAR_RANDOM_HPP
+
+#include "StarStaticRandom.hpp"
+#include "StarByteArray.hpp"
+
+namespace Star {
+
+STAR_EXCEPTION(RandomException, StarException);
+
+// Deterministic random number source.  Uses multiply-with-carry algorithm.
+// Much higher quality than the predictable random number generators.  Not
+// thread safe (won't crash or anything, but might return less than optimal
+// values).
+class RandomSource {
+public:
+  // Generates a RandomSource with a seed from Random::randu64()
+  RandomSource();
+  RandomSource(uint64_t seed);
+
+  // Re-initializes the random number generator using the given seed.  It is
+  // exactly equivalent to constructing a new RandomSource, just using the same
+  // buffer.
+  void init();
+  void init(uint64_t seed);
+
+  void addEntropy();
+  void addEntropy(uint64_t seed);
+
+  uint32_t randu32();
+  uint64_t randu64();
+
+  int32_t randi32();
+  int64_t randi64();
+
+  // Generates values in the range [0.0, 1.0]
+  float randf();
+  // Generates values in the range [0.0, 1.0]
+  double randd();
+
+  // Random integer from [0, max], max must be >= 0
+  int64_t randInt(int64_t max);
+  uint64_t randUInt(uint64_t max);
+
+  // Random integer from [min, max]
+  int64_t randInt(int64_t min, int64_t max);
+  uint64_t randUInt(uint64_t min, uint64_t max);
+
+  float randf(float min, float max);
+  double randd(double min, double max);
+
+  bool randb();
+
+  // Generates values via normal distribution with box-muller algorithm
+  float nrandf(float stddev = 1.0f, float mean = 0.0f);
+  double nrandd(double stddev = 1.0, double mean = 0.0);
+
+  // Round a fractional value statistically towards the floor or ceiling.  For
+  // example, if a value is 5.2, 80% of the time it will round to 5, but 20% of
+  // the time it will round to 6.
+  int64_t stochasticRound(double val);
+
+  void randBytes(char* buf, size_t len);
+  ByteArray randBytes(size_t len);
+
+  // Pick a random value out of a container
+  template <typename Container>
+  typename Container::value_type const& randFrom(Container const& container);
+  template <typename Container>
+  typename Container::value_type& randFrom(Container& container);
+  template <typename Container>
+  typename Container::value_type randValueFrom(Container const& container);
+  template <typename Container>
+  typename Container::value_type randValueFrom(Container const& container, typename Container::value_type const& defaultVal);
+
+  template <typename Container>
+  void shuffle(Container& container);
+
+private:
+  uint32_t gen32();
+
+  uint32_t m_data[256];
+  uint32_t m_carry;
+  uint8_t m_index;
+};
+
+// Global static versions of the methods in RandomSource.  It is not necessary
+// to initialize the global RandomSource manually, it will be automatically
+// initialized with a random seed on first use if it is not already initialized.
+namespace Random {
+  void init();
+  void init(uint64_t seed);
+
+  void addEntropy();
+  void addEntropy(uint64_t seed);
+
+  uint32_t randu32();
+  uint64_t randu64();
+  int32_t randi32();
+  int64_t randi64();
+  float randf();
+  double randd();
+  long long randInt(long long max);
+  unsigned long long randUInt(unsigned long long max);
+  long long randInt(long long min, long long max);
+  unsigned long long randUInt(unsigned long long min, unsigned long long max);
+  float randf(float min, float max);
+  double randd(double min, double max);
+  bool randb();
+
+  float nrandf(float stddev = 1.0f, float mean = 0.0f);
+  double nrandd(double stddev = 1.0, double mean = 0.0);
+
+  int64_t stochasticRound(double val);
+
+  void randBytes(char* buf, size_t len);
+  ByteArray randBytes(size_t len);
+
+  template <typename Container>
+  typename Container::value_type const& randFrom(Container const& container);
+  template <typename Container>
+  typename Container::value_type& randFrom(Container& container);
+  template <typename Container>
+  typename Container::value_type randValueFrom(Container const& container);
+  template <typename Container>
+  typename Container::value_type randValueFrom(Container const& container, typename Container::value_type const& defaultVal);
+
+  template <typename Container>
+  void shuffle(Container& container);
+}
+
+template <typename Container>
+typename Container::value_type const& RandomSource::randFrom(Container const& container) {
+  if (container.empty())
+    throw RandomException("Empty container in randFrom");
+
+  auto i = container.begin();
+  std::advance(i, randUInt(container.size() - 1));
+  return *i;
+}
+
+template <typename Container>
+typename Container::value_type& RandomSource::randFrom(Container& container) {
+  if (container.empty())
+    throw RandomException("Empty container in randFrom");
+
+  auto i = container.begin();
+  std::advance(i, randUInt(container.size() - 1));
+  return *i;
+}
+
+template <typename Container>
+typename Container::value_type const& Random::randFrom(Container const& container) {
+  if (container.empty())
+    throw RandomException("Empty container in randFrom");
+
+  auto i = container.begin();
+  std::advance(i, Random::randUInt(container.size() - 1));
+  return *i;
+}
+
+template <typename Container>
+typename Container::value_type& Random::randFrom(Container& container) {
+  if (container.empty())
+    throw RandomException("Empty container in randFrom");
+
+  auto i = container.begin();
+  std::advance(i, Random::randUInt(container.size() - 1));
+  return *i;
+}
+
+template <typename Container>
+typename Container::value_type RandomSource::randValueFrom(Container const& container) {
+  return randValueFrom(container, typename Container::value_type());
+}
+
+template <typename Container>
+typename Container::value_type RandomSource::randValueFrom(
+    Container const& container, typename Container::value_type const& defaultVal) {
+  if (container.empty())
+    return defaultVal;
+
+  auto i = container.begin();
+  std::advance(i, randInt(container.size() - 1));
+  return *i;
+}
+
+template <typename Container>
+void RandomSource::shuffle(Container& container) {
+  std::random_shuffle(container.begin(), container.end(), [this](size_t max) { return randUInt(max - 1); });
+}
+
+template <typename Container>
+typename Container::value_type Random::randValueFrom(Container const& container) {
+  return randValueFrom(container, typename Container::value_type());
+}
+
+template <typename Container>
+typename Container::value_type Random::randValueFrom(
+    Container const& container, typename Container::value_type const& defaultVal) {
+  if (container.empty())
+    return defaultVal;
+
+  auto i = container.begin();
+  std::advance(i, Random::randInt(container.size() - 1));
+  return *i;
+}
+
+template <typename Container>
+void Random::shuffle(Container& container) {
+  std::random_shuffle(container.begin(), container.end(), [](size_t max) { return Random::randUInt(max - 1); });
+}
+
+}
+
+#endif