_ak_mur_mur_hash_8h

Wwise SDK 2021.1.14

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 Version: v2021.1.14  Build: 6590

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 #ifndef _AKMURMURHASH_H_

 #define _AKMURMURHASH_H_

 #include <AK/SoundEngine/Common/AkTypes.h>

 #include <AK/Tools/Common/AkPlatformFuncs.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_