sharpetronics/zstd
1
0
Fork 0
mirror of https://github.com/facebook/zstd.git synced 2025-10-08 00:04:02 -04:00
Code Issues Projects Releases Wiki Activity

Shrink Pipeline from 4 Positions to 3

Browse Source
This commit is contained in:
W. Felix Handte 2021-08-18 13:44:27 -04:00
parent 387840af79
commit b092dd75b7
1 changed files with 10 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
lib/compress/zstd_fast.c
View File

@ -247,7 +247,6 @@ ZSTD_compressBlock_fast_generic_pipelined(
const BYTE* ip0 = istart;
const BYTE* ip1;
const BYTE* ip2;
const BYTE* ip3;
U32 current0;
U32 rep_offset1 = rep[0];
@ -257,12 +256,9 @@ ZSTD_compressBlock_fast_generic_pipelined(
size_t hash0; /* hash for ip0 */
size_t hash1; /* hash for ip1 */
size_t hash2; /* hash for ip2 */
size_t hash3; /* hash for ip3 */
U32 idx0; /* match idx for ip0 */
U32 idx1; /* match idx for ip1 */
U32 idx2; /* match idx for ip2 */
U32 mval; /* src value at match idx */
U32 rval; /* src value at ip2 - repcode */
U32 offcode;
const BYTE* match0;
@ -290,32 +286,20 @@ _start: /* Requires: ip0 */
/* calculate positions, ip0 - anchor == 0, so we skip step calc */
ip1 = ip0 + stepSize;
ip2 = ip1 + stepSize;
ip3 = ip2 + stepSize;
if (ip3 >= ilimit) {
if (ip2 >= ilimit) {
goto _cleanup;
}
hash0 = ZSTD_hashPtr(ip0, hlog, mls);
hash1 = ZSTD_hashPtr(ip1, hlog, mls);
hash2 = ZSTD_hashPtr(ip2, hlog, mls);
idx0 = hashTable[hash0];
idx1 = hashTable[hash1];
if (idx0 >= prefixStartIndex) {
mval = MEM_read32(base + idx0);
} else {
mval = MEM_read32(ip0) ^ 1;
}
rval = MEM_read32(ip2 - rep_offset1);
do {
const U32 rval = MEM_read32(ip2 - rep_offset1);
current0 = ip0 - base;
// DEBUGLOG(5, "Searching ip0 = %u", (U32)(ip0 - istart));
/* write back hash table entry */
hashTable[hash0] = current0;
@ -331,7 +315,7 @@ _start: /* Requires: ip0 */
goto _match;
}
/* load match for ip[1] */
/* load match for ip[0] */
if (idx0 >= prefixStartIndex) {
mval = MEM_read32(base + idx0);
} else {
@ -344,35 +328,29 @@ _start: /* Requires: ip0 */
goto _offset;
}
/* hash ip[3] */
hash3 = ZSTD_hashPtr(ip3, hlog, mls);
/* hash ip[2] */
hash2 = ZSTD_hashPtr(ip2, hlog, mls);
/* lookup ip[2] */
idx2 = hashTable[hash2];
/* load next rval */
rval = MEM_read32(ip3 - rep_offset1);
/* lookup ip[1] */
idx1 = hashTable[hash1];
/* advance to next positions */
{
if (ip2 >= nextStep) {
if (ip1 >= nextStep) {
step++;
nextStep += kStepIncr;
}
idx0 = idx1;
idx1 = idx2;
hash0 = hash1;
hash1 = hash2;
hash2 = hash3;
ip0 = ip1;
ip1 = ip2;
ip2 = ip3;
ip3 = ip3 + step;
ip2 = ip2 + step;
}
} while (ip3 < ilimit);
} while (ip2 < ilimit);
_cleanup: