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This commit is contained in:
Yann Collet 2018-05-02 10:33:12 -07:00
parent 0114b63b40
commit 1a191b3f8d
1 changed files with 20 additions and 53 deletions
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73
lib/lz4.c
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@ -1429,62 +1429,29 @@ LZ4_FORCE_INLINE int LZ4_decompress_generic(
*/
if ((endOnInput ? length != RUN_MASK : length <= 8) &&
/* strictly "less than" on input, to re-enter the loop with at least one byte */
likely((endOnInput ? ip < shortiend : 1) && (op <= shortoend)))
likely((endOnInput ? ip < shortiend : 1) & (op <= shortoend)))
{
/* Can we copy the literals with a single memcpy invocation? Sometimes we can't
* copy 16 bytes, because they can clobber the dictionary in the ring buffer. */
if (!endOnInput /* only 8 bytes */ || /* nothing to clobber */ dict != usingExtDict) {
/* Copy the literals. */
memcpy(op, ip, endOnInput ? 16 : 8);
op += length; ip += length;
/* Copy the literals. */
memcpy(op, ip, endOnInput ? 16 : 8);
op += length; ip += length;
/* The second stage: prepare for match copying, decode full info.
* It if doesn't work out, the info won't be wasted. */
length = token & ML_MASK; /* match length */
offset = LZ4_readLE16(ip); ip += 2;
match = op - offset;
/* The second stage: prepare for match copying, decode full info.
* If it doesn't work out, the info won't be wasted. */
length = token & ML_MASK; /* match length */
offset = LZ4_readLE16(ip); ip += 2;
match = op - offset;
/* Do not deal with overlapping matches. */
if ((length != 15) && (offset >= 8) &&
(dict==withPrefix64k || match >= lowPrefix))
{
/* Copy the match. */
memcpy(op + 0, match + 0, 8);
memcpy(op + 8, match + 8, 8);
memcpy(op +16, match +16, 2);
op += length + MINMATCH;
/* Both stages worked, load the next token. */
continue;
}
} else {
/* Save the literal length, can't copy 16 bytes just yet. */
size_t ll = length;
/* Prepare for the second satge. */
length = token & ML_MASK;
offset = LZ4_readLE16(ip+ll);
match = op + ll - offset;
if ((length != 15) && (offset >= 8) &&
(dict==withPrefix64k || match >= lowPrefix))
{
/* Copy the literals. */
memcpy(op, ip, 16);
op += ll; ip += ll + 2;
/* Copy the match. */
memcpy(op + 0, match + 0, 8);
memcpy(op + 8, match + 8, 8);
memcpy(op +16, match +16, 2);
op += length + MINMATCH;
/* Both stages worked, load the next token. */
continue;
}
/* So we took the literlas, but the second stage didn't work. */
memcpy(op, ip, 8);
if (ll > 8)
memcpy(op + 8, ip + 8, 8);
op += ll; ip += ll + 2;
/* Do not deal with overlapping matches. */
if ((length != 15) && (offset >= 8) &&
(dict==withPrefix64k || match >= lowPrefix))
{
/* Copy the match. */
memcpy(op + 0, match + 0, 8);
memcpy(op + 8, match + 8, 8);
memcpy(op +16, match +16, 2);
op += length + MINMATCH;
/* Both stages worked, load the next token. */
continue;
}
/* The second stage didn't work out, but the info is ready.