1 files changed, 97 insertions, 0 deletions

diff --git a/source/core/slang-random-generator.h b/source/core/slang-random-generator.h
new file mode 100644
index 000000000..7b3e42288
--- /dev/null
+++ b/source/core/slang-random-generator.h
@@ -0,0 +1,97 @@
+#ifndef SLANG_RANDOM_GENERATOR_H
+#define SLANG_RANDOM_GENERATOR_H
+
+#include "../../slang.h"
+
+#include <assert.h>
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "smart-pointer.h"
+
+namespace Slang { 
+
+class RandomGenerator: public RefObject
+{
+    public:
+
+        /// Make a copy of the generator in the same state
+    virtual RandomGenerator* clone() = 0;
+
+        /// Reset with a seed
+    virtual void reset(int32_t seed) = 0;
+        /// Next int32_t random number
+    virtual int32_t nextInt32() = 0;
+        /// Next int64_t random number
+    virtual int64_t nextInt64();
+
+        /// Get a 0-1 range floating point
+    virtual float nextUnitFloat32();
+        
+        /// Get the next bool
+    virtual bool nextBool();
+
+        /// Next Int32 which can only be positive
+    int32_t nextPositiveInt32() { return nextInt32() & 0x7fffffff; }
+        /// Next Int64 which can only be positive
+    int64_t nextPositiveInt64() { return nextInt64() & SLANG_INT64(0x7fffffffffffffff); }
+
+        /// Returns value up to BUT NOT INCLUDING maxValue. 
+    int32_t nextInt32UpTo(int32_t maxValue) { assert(maxValue > 0); return (maxValue <= 1) ? 0 : (nextPositiveInt32() % maxValue); }
+
+        /// Returns value from min up to BUT NOT INCLUDING max
+    int32_t nextInt32InRange(int32_t min, int32_t max);
+
+        /// Returns value up to BUT NOT INCLUDING maxValue
+    int64_t nextInt64UpTo(int64_t maxValue) { assert(maxValue > 0); return (maxValue <= 1) ? 0 : (nextPositiveInt64() % maxValue); }
+
+        /// Returns value from min up to BUT NOT INCLUDING max
+    int64_t nextInt64InRange(int64_t min, int64_t max);
+
+        /// Create a RandomGenerator with specified seed using default generator type
+    static RandomGenerator* create(int32_t seed);
+};
+
+/* Mersenne Twister random number generator 
+https://en.wikipedia.org/wiki/Mersenne_Twister
+*/
+class Mt19937RandomGenerator: public RandomGenerator
+{
+    public:
+    typedef Mt19937RandomGenerator ThisType;
+
+    enum 
+    {
+        kNumEntries = 624
+    };
+
+    Mt19937RandomGenerator* clone() SLANG_OVERRIDE { return new ThisType(*this); }
+    void reset(int32_t seed) SLANG_OVERRIDE;
+    int32_t nextInt32() SLANG_OVERRIDE;
+    
+        /// Ctor
+    Mt19937RandomGenerator();
+    Mt19937RandomGenerator(const ThisType& rhs);
+    explicit Mt19937RandomGenerator(int32_t seed);
+
+        /// Assignment
+    void operator=(const ThisType& rhs)
+    {
+        m_index = rhs.m_index;
+        ::memcpy(m_mt, rhs.m_mt, sizeof(m_mt));
+    }
+    
+    protected:
+    void _generate();
+
+    uint32_t m_mt[kNumEntries];             ///< The random state vector
+    int m_index;                            ///< If set to >= kMaxEntries it means reset
+
+};
+
+typedef Mt19937RandomGenerator DefaultRandomGenerator;
+
+} // namespace Slang
+
+#endif // SLANG_RANDOM_GENERATOR_H
\ No newline at end of file