75 lines
2.1 KiB
C++
75 lines
2.1 KiB
C++
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#include "sourcesdk/common.h"
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#include "snappy.h"
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#include "snappy-sinksource.h"
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#include <string.h>
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static const uint32 INVALID = static_cast<uint32>(-1);
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static const uint32 LZSS_ID = BigLong(('L' << 24) | ('Z' << 16) | ('S' << 8) | ('S'));
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static const uint32 SNAPPY_ID = BigLong(('S' << 24) | ('N' << 16) | ('A' << 8) | ('P'));
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inline uint32_t U8ToU32(const uint8* from)
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{
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union U8ToU32
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{
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uint8 bytes[4];
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uint32 dword;
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};
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return reinterpret_cast<const U8ToU32*>(from)->dword;
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}
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uint32 COM_BufferToBufferDecompress(uint8* dest, uint32 destLen, const uint8* src, uint32 srcLen)
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{
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const uint32 uncompressedLen = COM_GetUncompressedSize(src, srcLen);
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if (uncompressedLen == INVALID)
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{
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if (srcLen <= destLen)
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{
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memcpy(dest, src, srcLen);
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}
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}
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else if (uncompressedLen <= destLen)
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{
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const uint32 id = U8ToU32(src);
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if (id == LZSS_ID)
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{
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assert(false);
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}
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else if (id == SNAPPY_ID)
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{
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snappy::RawUncompress(reinterpret_cast<const char*>(src + 4), srcLen - 4, reinterpret_cast<char*>(dest));
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}
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}
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return (uncompressedLen != INVALID) ? uncompressedLen : 0;
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}
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uint32 COM_GetUncompressedSize(const uint8* data, uint32 numBytes)
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{
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uint32 uncompressedLength = INVALID;
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if (numBytes > 4)
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{
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const uint32 magic = U8ToU32(data);
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if (numBytes >= 8 && magic == LZSS_ID)
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{
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return U8ToU32(data + 4);
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}
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if (magic == SNAPPY_ID)
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{
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snappy::ByteArraySource source = {reinterpret_cast<const char*>(data + 4), numBytes - 4};
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snappy::GetUncompressedLength(&source, &uncompressedLength);
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}
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}
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return static_cast<uint32>(uncompressedLength);
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}
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uint32 COM_GetIdealDestinationCompressionBufferSize_Snappy(uint32 srcLen)
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{
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return snappy::MaxCompressedLength(srcLen) + sizeof(uint32);
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}
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/*uint32 COM_CompressBuffer_Snappy(const uint8* src, uint32 srcLen, uint8* dest, uint32 destLen)
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{
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return COM_GetIdealDestinationCompressionBufferSize_Snappy(srcLen);
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}*/
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