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Tidying up Miniz compression code.

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This commit is contained in:
Daviw Williams 2013-02-25 16:33:39 +01:00
parent 81eab0ebfb
commit 34671130fb
2 changed files with 18 additions and 18 deletions
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4
library/PolyVoxCore/include/PolyVoxCore/MinizCompressor.h
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@ -16,12 +16,12 @@ namespace PolyVox
uint32_t decompress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength); uint32_t decompress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength);
private: private:
int m_iCompressionLevel; unsigned int m_uCompressionFlags;
// tdefl_compressor contains all the state needed by the low-level compressor so it's a pretty big struct (~300k). // tdefl_compressor contains all the state needed by the low-level compressor so it's a pretty big struct (~300k).
// We're storing it by void* because miniz does not supply a header and we don't want to include the .c file from // We're storing it by void* because miniz does not supply a header and we don't want to include the .c file from
// here as it will cause linker problems. // here as it will cause linker problems.
void* g_deflator; void* m_pDeflator;
}; };
} }

32
library/PolyVoxCore/source/MinizCompressor.cpp
View File

@ -23,16 +23,25 @@ namespace PolyVox
{ {
// Compression levels: 0-9 are the standard zlib-style levels, 10 is best possible compression (not zlib compatible, and may be very slow) // Compression levels: 0-9 are the standard zlib-style levels, 10 is best possible compression (not zlib compatible, and may be very slow)
MinizCompressor::MinizCompressor(int iCompressionLevel) MinizCompressor::MinizCompressor(int iCompressionLevel)
:m_iCompressionLevel(iCompressionLevel) :m_pDeflator(0)
,g_deflator(0)
{ {
tdefl_compressor* pDeflator = new tdefl_compressor; tdefl_compressor* pDeflator = new tdefl_compressor;
g_deflator = reinterpret_cast<void*>(pDeflator); m_pDeflator = reinterpret_cast<void*>(pDeflator);
// The number of dictionary probes to use at each compression level (0-10). 0=implies fastest/minimal possible probing.
static const mz_uint s_tdefl_num_probes[11] = { 0, 1, 6, 32, 16, 32, 128, 256, 512, 768, 1500 };
// create tdefl() compatible flags (we have to compose the low-level flags ourselves, or use tdefl_create_comp_flags_from_zip_params() but that means MINIZ_NO_ZLIB_APIS can't be defined).
m_uCompressionFlags = TDEFL_WRITE_ZLIB_HEADER | s_tdefl_num_probes[MZ_MIN(10, iCompressionLevel)] | ((iCompressionLevel <= 3) ? TDEFL_GREEDY_PARSING_FLAG : 0);
if (!iCompressionLevel)
{
m_uCompressionFlags |= TDEFL_FORCE_ALL_RAW_BLOCKS;
}
} }
MinizCompressor::~MinizCompressor() MinizCompressor::~MinizCompressor()
{ {
tdefl_compressor* pDeflator = reinterpret_cast<tdefl_compressor*>(g_deflator); tdefl_compressor* pDeflator = reinterpret_cast<tdefl_compressor*>(m_pDeflator);
delete pDeflator; delete pDeflator;
} }
@ -68,19 +77,10 @@ namespace PolyVox
// but it's implemented using the lower level API which does not conflict with zlib or perform any memory allocations. // but it's implemented using the lower level API which does not conflict with zlib or perform any memory allocations.
uint32_t MinizCompressor::compress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength) uint32_t MinizCompressor::compress(void* pSrcData, uint32_t uSrcLength, void* pDstData, uint32_t uDstLength)
{ {
tdefl_compressor* pDeflator = reinterpret_cast<tdefl_compressor*>(g_deflator); tdefl_compressor* pDeflator = reinterpret_cast<tdefl_compressor*>(m_pDeflator);
// The number of dictionary probes to use at each compression level (0-10). 0=implies fastest/minimal possible probing. // It seems we have to reinitialise the deflator for each fresh dataset (it's probably intended for streaming, which we're not doing here)
static const mz_uint s_tdefl_num_probes[11] = { 0, 1, 6, 32, 16, 32, 128, 256, 512, 768, 1500 }; tdefl_status status = tdefl_init(pDeflator, NULL, NULL, m_uCompressionFlags);
// create tdefl() compatible flags (we have to compose the low-level flags ourselves, or use tdefl_create_comp_flags_from_zip_params() but that means MINIZ_NO_ZLIB_APIS can't be defined).
mz_uint comp_flags = TDEFL_WRITE_ZLIB_HEADER | s_tdefl_num_probes[MZ_MIN(10, m_iCompressionLevel)] | ((m_iCompressionLevel <= 3) ? TDEFL_GREEDY_PARSING_FLAG : 0);
if (!m_iCompressionLevel)
{
comp_flags |= TDEFL_FORCE_ALL_RAW_BLOCKS;
}
tdefl_status status = tdefl_init(pDeflator, NULL, NULL, comp_flags);
if (status != TDEFL_STATUS_OKAY) if (status != TDEFL_STATUS_OKAY)
{ {
stringstream ss; stringstream ss;