AuroraMiddleware/lz4
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added comments, as suggested by @terrelln

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This commit is contained in:
Yann Collet 2017-10-31 11:49:57 -07:00
parent e0914ff70c
commit 3f173052ae
1 changed files with 5 additions and 4 deletions
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9
lib/lz4.c
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@ -1180,15 +1180,16 @@ LZ4_FORCE_INLINE int LZ4_decompress_generic(
unsigned const token = *ip++;
/* shortcut for common case */
/* this shortcut was tested on x86 and x64, where it improves decoding speed.
/* shortcut for common case :
* in most circumstances, we expect to decode small matches (<= 16 bytes) separated by few literals (<= 14 bytes).
* this shortcut was tested on x86 and x64, where it improves decoding speed.
* it has not yet been benchmarked on ARM, Power, mips, etc. */
if (((ip + 14 + 2 <= iend) & (op + 14 + 16 <= oend))
& ((token < 15*16) & ((token & 0xF) <= 12)) ) {
& ((token < (15<<ML_BITS)) & ((token & 0xF) <= 12)) ) {
size_t const ll = token >> ML_BITS;
size_t const off = LZ4_readLE16(ip+ll);
const BYTE* const matchPtr = op + ll - off; /* pointer underflow risk ? */
if ((off >= 16) & (matchPtr >= lowPrefix)) {
if ((off >= 16) /* do not deal with overlapping matches */ & (matchPtr >= lowPrefix)) {
size_t const ml = (token & 0xF) + MINMATCH;
memcpy(op, ip, 16); op += ll; ip += ll + 2 /*offset*/;
memcpy(op, matchPtr, 16); op += ml;