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Improved decompression speed

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This commit is contained in:
Yann Collet 2014-06-12 23:29:06 +01:00
parent 2040c97c63
commit 8ee9e6d04e
1 changed files with 33 additions and 23 deletions
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56
lz4.c Executable file → Normal file
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@ -111,6 +111,7 @@
#endif
#ifdef _MSC_VER /* Visual Studio */
# define FORCE_INLINE static __forceinline
# include <intrin.h> /* For Visual 2005 */
# if LZ4_ARCH64 /* 64-bits */
# pragma intrinsic(_BitScanForward64) /* For Visual 2005 */
@ -120,6 +121,15 @@
# pragma intrinsic(_BitScanReverse) /* For Visual 2005 */
# endif
# pragma warning(disable : 4127) /* disable: C4127: conditional expression is constant */
#else
# ifdef __GNUC__
# define FORCE_INLINE static inline __attribute__((always_inline))
# else
# define FORCE_INLINE static inline
# endif
#endif
#ifdef _MSC_VER /* Visual Studio */
# define lz4_bswap16(x) _byteswap_ushort(x)
#else
# define lz4_bswap16(x) ((unsigned short int) ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8)))
@ -831,7 +841,7 @@ int LZ4_moveDict (void* LZ4_dict, char* safeBuffer, int dictSize)
* Note that it is essential this generic function is really inlined,
* in order to remove useless branches during compilation optimisation.
*/
static int LZ4_decompress_generic(
FORCE_INLINE int LZ4_decompress_generic(
const char* source,
char* dest,
int inputSize,
@ -855,18 +865,19 @@ static int LZ4_decompress_generic(
BYTE* cpy;
BYTE* oexit = op + targetOutputSize;
const BYTE* const dictEnd = (dict==usingExtDict) ? (const BYTE*)dictStart + dictSize : NULL;
const BYTE* const dictEnd = (const BYTE*)dictStart + dictSize;
const size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0}; /* static reduces speed for LZ4_decompress_safe() on GCC64 */
/*const size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0}; / static reduces speed for LZ4_decompress_safe() on GCC64 */
const size_t dec32table[] = {4-0, 4-3, 4-2, 4-3, 4-0, 4-0, 4-0, 4-0}; /* static reduces speed for LZ4_decompress_safe() on GCC64 */
static const size_t dec64table[] = {0, 0, 0, (size_t)-1, 0, 1, 2, 3};
/* Special cases */
(void)dictStart; (void)dictSize;
if ((partialDecoding) && (oexit> oend-MFLIMIT)) oexit = oend-MFLIMIT; /* targetOutputSize too high => decode everything */
if ((partialDecoding) && (oexit> oend-MFLIMIT)) oexit = oend-MFLIMIT; /* targetOutputSize too high => decode everything */
if ((endOnInput) && (unlikely(outputSize==0))) return ((inputSize==1) && (*ip==0)) ? 0 : -1; /* Empty output buffer */
if ((!endOnInput) && (unlikely(outputSize==0))) return (*ip==0?1:-1);
/* Main Loop */
while (1)
{
@ -878,7 +889,11 @@ static int LZ4_decompress_generic(
if ((length=(token>>ML_BITS)) == RUN_MASK)
{
unsigned s=255;
while (((endOnInput)?ip<iend:1) && (s==255)) { s = *ip++; length += s; }
while (((endOnInput)?ip<iend:1) && (s==255))
{
s = *ip++;
length += s;
}
}
/* copy literals */
@ -910,17 +925,13 @@ static int LZ4_decompress_generic(
/* get matchlength */
if ((length=(token&ML_MASK)) == ML_MASK)
{
_readNextMLByte:
if ((!endOnInput) || (ip<iend-(LASTLITERALS+1))) /* Ensure enough bytes remain for LASTLITERALS + token */
unsigned s;
do
{
unsigned s = *ip++;
if (endOnInput && (ip > iend-LASTLITERALS)) goto _output_error;
s = *ip++;
length += s;
if (s==255) goto _readNextMLByte;
}
else
{
goto _output_error;
}
} while (s==255);
}
/* check external dictionary */
@ -963,9 +974,12 @@ static int LZ4_decompress_generic(
op[1] = ref[1];
op[2] = ref[2];
op[3] = ref[3];
op += 4, ref += 4; ref -= dec32table[op-ref];
/*op += 4, ref += 4; ref -= dec32table[op-ref];
A32(op) = A32(ref);
op += STEPSIZE-4; ref -= dec64;
op += STEPSIZE-4; ref -= dec64;*/
ref += dec32table[op-ref];
A32(op+4) = A32(ref);
op += STEPSIZE; ref -= dec64;
} else { LZ4_COPYSTEP(op,ref); }
cpy = op + length - (STEPSIZE-4);
@ -1015,11 +1029,7 @@ int LZ4_decompress_safe_partial(const char* source, char* dest, int compressedSi
int LZ4_decompress_fast(const char* source, char* dest, int originalSize)
{
#ifdef _MSC_VER /* This version is faster with Visual */
return LZ4_decompress_generic(source, dest, 0, originalSize, endOnOutputSize, full, 0, noDict, NULL, 0);
#else
return LZ4_decompress_generic(source, dest, 0, originalSize, endOnOutputSize, full, 0, withPrefix64k, NULL, 0);
#endif
}
int LZ4_decompress_fast_withPrefix64k(const char* source, char* dest, int originalSize)
@ -1086,7 +1096,7 @@ int LZ4_sizeofState() { return LZ4_STREAMSIZE; }
int LZ4_compress_withState (void* state, const char* source, char* dest, int inputSize)
{
if (((size_t)(state)&3) != 0) return 0; /* Error : state is not aligned on 4-bytes boundary */
MEM_INIT(state, 0, LZ4_sizeofState());
MEM_INIT(state, 0, LZ4_STREAMSIZE);
if (inputSize < (int)LZ4_64KLIMIT)
return LZ4_compress_generic(state, source, dest, inputSize, 0, notLimited, byU16, noDict);
@ -1097,7 +1107,7 @@ int LZ4_compress_withState (void* state, const char* source, char* dest, int inp
int LZ4_compress_limitedOutput_withState (void* state, const char* source, char* dest, int inputSize, int maxOutputSize)
{
if (((size_t)(state)&3) != 0) return 0; /* Error : state is not aligned on 4-bytes boundary */
MEM_INIT(state, 0, LZ4_sizeofState());
MEM_INIT(state, 0, LZ4_STREAMSIZE);
if (inputSize < (int)LZ4_64KLIMIT)
return LZ4_compress_generic(state, source, dest, inputSize, maxOutputSize, limitedOutput, byU16, noDict);