Add Retro compliant CCRC32

Runtime/CCRC32.hpp

@@ -0,0 +1,15 @@
+#ifndef RETRO_CRC32_HPP
+#define RETRO_CRC32_HPP
+#include <cstdint>
+
+class CCRC32
+{
+    static const uint32_t crc32Table[256];
+    static inline uint32_t permute(uint32_t checksum, uint8_t b)
+    { return (checksum >> 8) ^ crc32Table[(checksum & 0xFF) ^ b]; }
+
+public:
+    static uint32_t Calculate(const void* data, uint32_t length);
+};
+
+#endif