several core runtime stubs added

Runtime/CRandom16.hpp

@@ -0,0 +1,80 @@
+#ifndef RETRO_CRANDOM16_HPP
+#define RETRO_CRANDOM16_HPP
+
+#include <stdint.h>
+
+namespace Retro
+{
+
+extern class CRandom16* GLOBAL_RANDOM;
+extern class CGlobalRandom* GLOBAL_RANDOM_TOKEN;
+
+class CRandom16
+{
+    uint32_t m_seed;
+public:
+    CRandom16(uint32_t p) : m_seed(p) {}
+
+    inline uint32_t Next()
+    {
+        m_seed = (m_seed * 0x41c64e6d) + 0x00003039;
+        return m_seed >> 16;
+    }
+
+    inline uint32_t GetSeed() const
+    {
+        return m_seed;
+    }
+
+    inline void SetSeed(uint32_t p)
+    {
+        m_seed = p;
+    }
+
+    inline float Float()
+    {
+        return Next() * 0.000015259022;
+    }
+
+    inline float Range(float min, float max)
+    {
+        return min + Float() * (max - min);
+    }
+
+    inline int32_t Range(int32_t min, int32_t max)
+    {
+        int64_t diff = max - min;
+        int64_t rand = -1;
+        while (rand < 0)
+            rand = int32_t((Next() << 16) | Next());
+        return rand % diff + min;
+    }
+
+    static CRandom16* GetRandomNumber() {return GLOBAL_RANDOM;}
+    static void SetRandomNumber(CRandom16* rnd) {GLOBAL_RANDOM = rnd;}
+};
+
+class CGlobalRandom
+{
+    CRandom16& m_random;
+    CGlobalRandom* m_prev;
+public:
+    CGlobalRandom(CRandom16& rand)
+    : m_random(rand), m_prev(GLOBAL_RANDOM_TOKEN)
+    {
+        GLOBAL_RANDOM_TOKEN = this;
+        CRandom16::SetRandomNumber(&m_random);
+    }
+    ~CGlobalRandom()
+    {
+        GLOBAL_RANDOM_TOKEN = m_prev;
+        if (m_prev)
+            CRandom16::SetRandomNumber(&m_prev->m_random);
+        else
+            CRandom16::SetRandomNumber(nullptr);
+    }
+};
+
+}
+
+#endif // RETRO_CRANDOM16_HPP