dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2024-12-27 22:28:22 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

lossless: simplify HashChainFindCopy heuristics

Browse Source 
for small speedup
0.0003 % worse compression

Change-Id: Ic4b6b21e5279231c6321f2cec1c79f7e17e56afa
This commit is contained in:
Jyrki Alakuijala 2015-06-23 14:25:06 +00:00 committed by James Zern
parent 888429f409
commit 8e9c94dedb
1 changed files with 9 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
src/enc/backward_references.c
View File

@ -281,34 +281,32 @@ static int HashChainFindCopy(const VP8LHashChain* const p,
int* const distance_ptr, int* const distance_ptr,
int* const length_ptr) { int* const length_ptr) {
const uint32_t* const argb_start = argb + base_position; const uint32_t* const argb_start = argb + base_position;
int iter = 0; int iter = iter_max;
int best_length = 1; int best_length = 1;
const int length_max = 256;
int best_distance = 0; int best_distance = 0;
const int min_pos = const int min_pos =
(base_position > window_size) ? base_position - window_size : 0; (base_position > window_size) ? base_position - window_size : 0;
int pos; int pos;
int length_max = 256;
if (max_len < length_max) {
length_max = max_len;
}
assert(xsize > 0); assert(xsize > 0);
for (pos = p->hash_to_first_index_[GetPixPairHash64(argb_start)]; for (pos = p->hash_to_first_index_[GetPixPairHash64(argb_start)];
pos >= min_pos; pos >= min_pos;
pos = p->chain_[pos]) { pos = p->chain_[pos]) {
int curr_length; int curr_length;
int distance; int distance;
if (iter > 8) { if (--iter < 0) {
if (iter > iter_max || best_length >= length_max) { break;
break;
}
} }
++iter;
curr_length = FindMatchLength(argb + pos, argb_start, best_length, max_len); curr_length = FindMatchLength(argb + pos, argb_start, best_length, max_len);
if (curr_length < best_length) continue;
distance = base_position - pos;
if (best_length < curr_length) { if (best_length < curr_length) {
distance = base_position - pos;
best_length = curr_length; best_length = curr_length;
best_distance = distance; best_distance = distance;
if (curr_length >= max_len) { if (curr_length >= length_max) {
break; break;
} }
if ((distance == 1 || distance == xsize) && if ((distance == 1 || distance == xsize) &&