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Merge "Small LZ77 speedups."

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This commit is contained in:
Pascal Massimino 2016-09-22 12:50:13 +00:00 committed by Gerrit Code Review
commit eee0cce158
1 changed files with 9 additions and 14 deletions
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23
src/enc/backward_references.c
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@ -247,7 +247,6 @@ int VP8LHashChainFill(VP8LHashChain* const p, int quality,
int low_effort) {
const int size = xsize * ysize;
const int iter_max = GetMaxItersForQuality(quality);
const int iter_min = iter_max - quality / 10;
const uint32_t window_size = GetWindowSizeForHashChain(quality, xsize);
int pos;
int argb_comp;
@ -331,6 +330,7 @@ int VP8LHashChainFill(VP8LHashChain* const p, int quality,
int iter = iter_max;
int best_length = 0;
uint32_t best_distance = 0;
uint32_t best_argb;
const int min_pos =
(base_position > window_size) ? base_position - window_size : 0;
const int length_max = (max_len < 256) ? max_len : 256;
@ -360,26 +360,21 @@ int VP8LHashChainFill(VP8LHashChain* const p, int quality,
// Skip the for loop if we already have the maximum.
if (best_length == MAX_LENGTH) pos = min_pos - 1;
}
best_argb = argb_start[best_length];
for (; pos >= min_pos; pos = chain[pos]) {
for (; pos >= min_pos && --iter; pos = chain[pos]) {
int curr_length;
if (--iter < 0) {
break;
}
assert(base_position > (uint32_t)pos);
curr_length =
FindMatchLength(argb + pos, argb_start, best_length, max_len);
if (argb[pos + best_length] != best_argb) continue;
curr_length = VP8LVectorMismatch(argb + pos, argb_start, max_len);
if (best_length < curr_length) {
best_length = curr_length;
best_distance = base_position - pos;
// Stop if we have reached the maximum length. Otherwise, make sure
// we have executed a minimum number of iterations depending on the
// quality.
if ((best_length == MAX_LENGTH) ||
(curr_length >= length_max && iter < iter_min)) {
break;
}
best_argb = argb_start[best_length];
// Stop if we have reached a good enough length.
if (best_length >= length_max) break;
}
}
// We have the best match but in case the two intervals continue matching