_ak_mur_mur_hash_8h

Wwise SDK 2024.1.0

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 #ifndef _AKMURMURHASH_H_
 #define _AKMURMURHASH_H_
  
 #include <AK/SoundEngine/Common/AkTypes.h>
 #include <AK/Tools/Common/AkBitFuncs.h>
  
 // https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp
  
 #define MURMUR3_SEED    ( 0x41545731 )
 #define MURMUR3_C1      ( 0xcc9e2d51 )
 #define MURMUR3_C2      ( 0x1b873593 )
 #define MURMUR3_C3      ( 0xe6546b64 )
  
 AkForceInline AkUInt32 AkHashMurMurMix32( AkUInt32 uValue )
 {
     uValue ^= uValue >> 16;
     uValue *= 0x85ebca6b;
     uValue ^= uValue >> 13;
     uValue *= 0xc2b2ae35;
     uValue ^= uValue >> 16;
     return uValue;
 }
  
 AkForceInline AkUInt64 AkHashMurMurMix64( AkUInt64 uValue ) {
     uValue ^= uValue >> 33;
     uValue *= 0xff51afd7ed558ccd;
     uValue ^= uValue >> 33;
     uValue *= 0xc4ceb9fe1a85ec53;
     uValue ^= uValue >> 33;
     return uValue;
 }
  
 AkForceInline void AkHashMurMur32( AkUInt32* pHash, const void* pData, size_t uSize ) {
     AkUInt32 uH1 = MURMUR3_SEED;
     AkUInt8* pBytes = ( AkUInt8* )pData;
     AkUInt32 uNumBlocks = ( AkUInt32 )( uSize / 4 );
     AkUInt32* pBlocks = ( AkUInt32* )( pBytes + ( uNumBlocks * 4 ) );
     for ( AkInt32 i = -( AkInt32 )uNumBlocks; i; ++i ) {
         AkUInt32 uK1 = *( AkUInt32* )( pBlocks + i );
         uK1 *= MURMUR3_C1;
         uK1 = AK::ROTL32( uK1, 15 );
         uK1 *= MURMUR3_C2;
         uH1 ^= uK1;
         uH1 = AK::ROTL32( uH1, 13 );
         uH1 = uH1 * 5 + MURMUR3_C3;
     }
     AkUInt8* pBytesTail = ( AkUInt8* )( pBytes + ( uNumBlocks * 4 ) );
     AkUInt32 uK1 = 0;
     switch ( uSize & 3 ) {
     case 3: uK1 ^= pBytesTail[ 2 ] << 16;
     case 2: uK1 ^= pBytesTail[ 1 ] << 8;
     case 1: uK1 ^= pBytesTail[ 0 ];
             uK1 *= MURMUR3_C1;
             uK1 = AK::ROTL32( uK1, 15 );
             uK1 *= MURMUR3_C2;
             uH1 ^= uK1;
     }
     uH1 ^= uSize;
     uH1 = AkHashMurMurMix32( uH1 );
     *pHash = uH1;
 }
  
 #endif // _AKMURMURHASH_H_