1 files changed, 143 insertions, 0 deletions
diff --git a/source/core/slang-random-generator.cpp b/source/core/slang-random-generator.cpp
new file mode 100644
index 000000000..7e8476c30
--- /dev/null
+++ b/source/core/slang-random-generator.cpp
@@ -0,0 +1,143 @@
+
+#include "slang-random-generator.h"
+
+namespace Slang {
+
+/* !!!!!!!!!!!!!!!!!!!!!!!!!!!! RandomGenerator !!!!!!!!!!!!!!!!!!!!!!!! */
+
+float RandomGenerator::nextUnitFloat32()
+{
+    int32_t intValue = nextInt32();
+    return (intValue & 0x7fffffff) * (1.0f / 0x7fffffff);
+}
+
+bool RandomGenerator::nextBool()
+{
+    uint32_t bits = uint32_t(nextInt32());
+
+    // Xor together all bits in each byte
+    bits = ((bits & 0xaaaaaaaa) >> 1) ^ (bits & 0x55555555);
+    bits = ((bits & 0x44444444) >> 2) ^ (bits & 0x11111111);
+    bits = ((bits & 0x10101010) >> 4) ^ (bits & 0x01010101);
+
+    // In effect is the xor of all the bits of the original last byte 
+    return ( bits & 1) != 0;
+}
+
+int64_t RandomGenerator::nextInt64()
+{
+    const int32_t high = nextInt32();
+    const int32_t low = nextInt32();
+
+    return (int64_t(high) << 32) | low;
+}
+
+int32_t RandomGenerator::nextInt32InRange(int32_t min, int32_t max)
+{
+    int32_t diff = max - min;
+    if (diff <= 1)
+    {
+        return min;
+    }
+
+    return (nextPositiveInt32() % diff) + min;
+}
+
+int64_t RandomGenerator::nextInt64InRange(int64_t min, int64_t max)
+{
+    int64_t diff = max - min;
+    if (diff <= 1)
+    {
+        return min;
+    }
+    return (nextPositiveInt64() % diff) + min;
+}
+
+/* static */RandomGenerator* RandomGenerator::create(int32_t seed)
+{
+    return new DefaultRandomGenerator(seed);
+}
+
+/* !!!!!!!!!!!!!!!!!!!!!!!!!!!! Mt19937RandomGenerator !!!!!!!!!!!!!!!!!!!!!!!! */
+
+Mt19937RandomGenerator::Mt19937RandomGenerator()
+{
+    reset(21452);
+}
+
+Mt19937RandomGenerator::Mt19937RandomGenerator(const ThisType& rhs)
+{
+    *this = rhs;
+}
+
+Mt19937RandomGenerator::Mt19937RandomGenerator(int32_t seed)
+{
+    reset(seed);
+}
+
+void Mt19937RandomGenerator::_generate()
+{
+    const uint32_t xorValue = 2567483615u;
+    for (int i = 0; i < kNumEntries - 1; ++i)
+    {
+        const uint32_t y = (m_mt[i] & 0x80000000) + (m_mt[i + 1] & 0x7fffffff);    
+
+        // o = (i + 397) % kNumEntries
+        int32_t o = i + 397;
+        o = (o >= kNumEntries) ? (o - kNumEntries) : o;
+
+        m_mt[i] = m_mt[o] ^ (y >> 1);
+        // If y is odd
+        if (y & 1)
+        {
+            m_mt[i] = m_mt[i] ^ xorValue;
+        }
+    }
+
+    // Last
+    {
+        const int i = kNumEntries - 1;
+        const uint32_t y = (m_mt[i] & 0x80000000) + (m_mt[0] & 0x7fffffff);
+        const int32_t o = ((i + 397) - kNumEntries);
+
+        m_mt[i] = m_mt[o] ^ (y >> 1);
+        // If y is odd
+        if (y & 1)
+        {
+            m_mt[i] = m_mt[i] ^ xorValue;
+        }
+    }
+
+    m_index = 0;
+}
+
+void Mt19937RandomGenerator::reset(int32_t seedIn)
+{
+    m_index = 0;
+    m_mt[0] = uint32_t(seedIn);
+    for (int i = 1; i < kNumEntries; ++i)
+    {
+        m_mt[i] = (1812433253 * (m_mt[i - 1] ^ (m_mt[i - 1] >> 30)) + i);
+    }
+}
+
+int32_t Mt19937RandomGenerator::nextInt32()
+{
+    if (m_index >= kNumEntries)
+    {
+        _generate();
+    }
+
+    uint32_t y = m_mt[m_index++];
+    y = y ^ (y >> 11);
+    y = y ^ ((y << 7) & uint32_t(0x9d2c5680u));
+    y = y ^ ((y << 15) & uint32_t(0xefc6000u)); 
+    y = y ^ (y >> 18);
+
+    return int32_t(y);
+}
+
+
+
+
+} // namespace Slang