demboyz/external/sourcesdk/common.cpp
2016-04-20 21:18:56 -04:00

73 lines
2.0 KiB
C++

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