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fix #876

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by introducing a max limit acceleration value
This commit is contained in:
Yann Collet 2020-08-10 11:03:27 -07:00
parent b01c58000e
commit 7b1b078dfc
2 changed files with 16 additions and 6 deletions
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19
lib/lz4.c
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@ -45,10 +45,16 @@
#endif
/*
* ACCELERATION_DEFAULT :
* LZ4_ACCELERATION_DEFAULT :
* Select "acceleration" for LZ4_compress_fast() when parameter value <= 0
*/
#define ACCELERATION_DEFAULT 1
#define LZ4_ACCELERATION_DEFAULT 1
/*
* LZ4_ACCELERATION_MAX :
* Any "acceleration" value higher than this threshold
* get treated as LZ4_ACCELERATION_MAX instead (fix #876)
*/
#define LZ4_ACCELERATION_MAX 65537
/*-************************************
@ -1200,7 +1206,8 @@ int LZ4_compress_fast_extState(void* state, const char* source, char* dest, int
{
LZ4_stream_t_internal* const ctx = & LZ4_initStream(state, sizeof(LZ4_stream_t)) -> internal_donotuse;
assert(ctx != NULL);
if (acceleration < 1) acceleration = ACCELERATION_DEFAULT;
if (acceleration < 1) acceleration = LZ4_ACCELERATION_DEFAULT;
if (acceleration > LZ4_ACCELERATION_MAX) acceleration = LZ4_ACCELERATION_MAX;
if (maxOutputSize >= LZ4_compressBound(inputSize)) {
if (inputSize < LZ4_64Klimit) {
return LZ4_compress_generic(ctx, source, dest, inputSize, NULL, 0, notLimited, byU16, noDict, noDictIssue, acceleration);
@ -1230,7 +1237,8 @@ int LZ4_compress_fast_extState(void* state, const char* source, char* dest, int
int LZ4_compress_fast_extState_fastReset(void* state, const char* src, char* dst, int srcSize, int dstCapacity, int acceleration)
{
LZ4_stream_t_internal* ctx = &((LZ4_stream_t*)state)->internal_donotuse;
if (acceleration < 1) acceleration = ACCELERATION_DEFAULT;
if (acceleration < 1) acceleration = LZ4_ACCELERATION_DEFAULT;
if (acceleration > LZ4_ACCELERATION_MAX) acceleration = LZ4_ACCELERATION_MAX;
if (dstCapacity >= LZ4_compressBound(srcSize)) {
if (srcSize < LZ4_64Klimit) {
@ -1514,7 +1522,8 @@ int LZ4_compress_fast_continue (LZ4_stream_t* LZ4_stream,
if (streamPtr->dirty) { return 0; } /* Uninitialized structure detected */
LZ4_renormDictT(streamPtr, inputSize); /* avoid index overflow */
if (acceleration < 1) acceleration = ACCELERATION_DEFAULT;
if (acceleration < 1) acceleration = LZ4_ACCELERATION_DEFAULT;
if (acceleration > LZ4_ACCELERATION_MAX) acceleration = LZ4_ACCELERATION_MAX;
/* invalidate tiny dictionaries */
if ( (streamPtr->dictSize-1 < 4-1) /* intentional underflow */

3
lib/lz4.h
View File

@ -186,7 +186,8 @@ LZ4LIB_API int LZ4_compressBound(int inputSize);
The larger the acceleration value, the faster the algorithm, but also the lesser the compression.
It's a trade-off. It can be fine tuned, with each successive value providing roughly +~3% to speed.
An acceleration value of "1" is the same as regular LZ4_compress_default()
Values <= 0 will be replaced by ACCELERATION_DEFAULT (currently == 1, see lz4.c).
Values <= 0 will be replaced by LZ4_ACCELERATION_DEFAULT (currently == 1, see lz4.c).
Values > LZ4_ACCELERATION_MAX will be replaced by LZ4_ACCELERATION_MAX (currently == 65537, see lz4.c).
*/
LZ4LIB_API int LZ4_compress_fast (const char* src, char* dst, int srcSize, int dstCapacity, int acceleration);