TCompress_Decompress.cpp

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#include "ToshiPCH.h"
#include "TCompress.h"
 
//-----------------------------------------------------------------------------
// Enables memory debugging.
// Note: Should be the last include!
//-----------------------------------------------------------------------------
#include "Core/TMemoryDebugOn.h"
 
TOSHI_NAMESPACE_START
 
// $Barnyard: FUNCTION 006dc4f0
uintptr_t TCompress::Decompress( TFile* file, TCompress::Header* header, TBYTE* buffer, TUINT32 bufferSize )
{
    TPROFILER_SCOPE();
 
    if ( header->Magic != TFourCC( "BTEC" ) )
        return TCOMPRESS_ERROR_WRONG_MAGIC;
    if ( header->Version != TVERSION( 1, 2 ) && header->Version != TVERSION( 1, 3 ) )
        return TCOMPRESS_ERROR_WRONG_VERSION;
    if ( header->Size > bufferSize )
        return TCOMPRESS_ERROR_WRONG_SIZE;
 
    TBYTE*  pBufferPos     = buffer;
    TUINT32 compressedLeft = header->CompressedSize;
 
    while ( compressedLeft > 0 )
    {
        TUINT32 chunkSize;
        TBOOL   noOffset;
        TINT    offset;
 
        compressedLeft -= GetCommand( file, noOffset, chunkSize, offset );
 
        if ( !noOffset )
        {
            // The data is already unpacked so just copy it
            TBYTE* unpackedData = pBufferPos - offset;
 
            while ( chunkSize > 0 )
            {
                *( pBufferPos++ ) = *( unpackedData++ );
                chunkSize--;
            }
        }
        else
        {
            // The data wasn't previously unpacked, read it from file
            TSIZE readedCount = file->Read( pBufferPos, chunkSize );
            pBufferPos += readedCount;
            compressedLeft -= readedCount;
        }
    }
 
    if ( header->Version == TVERSION( 1, 3 ) )
    {
        pBufferPos = buffer;
        for ( TSIZE i = 0; i < header->Size; i++, pBufferPos++ )
        {
            *pBufferPos ^= header->XorValue;
        }
    }
 
    uintptr_t sizeDecompressed = pBufferPos - buffer;
    TASSERT( sizeDecompressed == header->Size, "Wrong decompressed size" );
 
    return sizeDecompressed;
}
 
// $Barnyard: FUNCTION 006dc220
int8_t TCompress::GetHeader( TFile* file, TCompress::Header& btecHeader )
{
    TUINT32 headerSize = TCompress::HEADER_SIZE_12;
    TUINT32 savedPos   = file->Tell();
    TSIZE   readedSize = file->Read( &btecHeader, headerSize );
 
    if ( ms_bIsBigEndian )
    {
        btecHeader.Size           = CONVERTENDIANESS( Endianess_Big, btecHeader.Size );
        btecHeader.CompressedSize = CONVERTENDIANESS( Endianess_Big, btecHeader.CompressedSize );
        btecHeader.Magic          = CONVERTENDIANESS( Endianess_Big, btecHeader.Magic );
        btecHeader.Version        = CONVERTENDIANESS( Endianess_Big, btecHeader.Version.Value );
    }
 
    if ( btecHeader.Version == TVERSION( 1, 3 ) )
    {
        readedSize += file->Read( &btecHeader.XorValue, sizeof( TCompress::Header::XorValue ) );
        headerSize += sizeof( TCompress::Header::XorValue );
 
        if ( ms_bIsBigEndian )
        {
            btecHeader.XorValue = CONVERTENDIANESS( Endianess_Big, btecHeader.XorValue );
        }
    }
 
    if ( readedSize != headerSize )
    {
        file->Seek( savedPos, TSEEK_SET );
        return TCOMPRESS_ERROR_WRONG_HEADERSIZE;
    }
 
    if ( btecHeader.Magic != TFourCC( "BTEC" ) )
    {
        file->Seek( savedPos, TSEEK_SET );
        return TCOMPRESS_ERROR_WRONG_MAGIC;
    }
 
    return TCOMPRESS_ERROR_OK;
}
 
// With the help of Revel8n approach
// Could use some code cleanup
// $Barnyard: FUNCTION 006dc340
TINT TCompress::GetCommand( TFile* file, TBOOL& noOffset, TUINT32& size, TINT& offset )
{
    TINT  read_count = file->Read( &size, 1 );
    TBOOL isBigSize  = size & BTECSizeFlag_BigSize;
    noOffset         = size & BTECSizeFlag_NoOffset;
    offset           = -1;
 
    // by default size is 6 bits long
    size &= BTECSizeFlag_SizeMask;
 
    if ( isBigSize )
    {
        // now the size is 14 bits long
        uint8_t secondByte;
        read_count += file->Read( &secondByte, 1 );
        size = ( size << 8 ) | secondByte;
    }
 
    if ( !noOffset )
    {
        // by default offset is 7 bits long
        read_count += file->Read( &offset, 1 );
        TBOOL bigOffset = offset & BTECOffsetFlag_BigOffset;
        offset &= BTECOffsetFlag_OffsetMask;
 
        if ( bigOffset )
        {
            // now the offset is 15 bits long
            uint8_t secondByte;
            read_count += file->Read( &secondByte, 1 );
            offset = ( offset << 8 ) | secondByte;
        }
    }
 
    size += 1;
    offset += 1;
 
    return read_count;
}
 
TOSHI_NAMESPACE_END