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shuffle variables in HashChainFindCopy

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might lead to observable speed-up on some compiler/arch

Change-Id: I6c89ec9cd4f490e7e22b790785f80097a47d27b5
This commit is contained in:
Pascal Massimino 2012-07-16 19:08:59 -07:00
parent 8130c4cc64
commit cdf885c67c
1 changed files with 8 additions and 6 deletions
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14
src/enc/backward_references.c
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@ -146,18 +146,20 @@ static int HashChainFindCopy(const HashChain* const p,
const uint64_t hash_code = GetPixPairHash64(&argb[index]); const uint64_t hash_code = GetPixPairHash64(&argb[index]);
int prev_length = 0; int prev_length = 0;
int64_t best_val = 0; int64_t best_val = 0;
int best_length = 0;
int best_distance = 0;
const uint32_t* const argb_start = argb + index;
const int iter_min_mult = (quality < 50) ? 2 : (quality < 75) ? 4 : 8; const int iter_min_mult = (quality < 50) ? 2 : (quality < 75) ? 4 : 8;
const int iter_min = -quality * iter_min_mult; const int iter_min = -quality * iter_min_mult;
int iter_cnt = 10 + (quality >> 1); int iter_cnt = 10 + (quality >> 1);
const int min_pos = (index > WINDOW_SIZE) ? index - WINDOW_SIZE : 0; const int min_pos = (index > WINDOW_SIZE) ? index - WINDOW_SIZE : 0;
int32_t pos; int pos;
int64_t val;
int best_length = 0;
int best_distance = 0;
assert(xsize > 0); assert(xsize > 0);
for (pos = p->hash_to_first_index_[hash_code]; for (pos = p->hash_to_first_index_[hash_code];
pos >= min_pos; pos >= min_pos;
pos = p->chain_[pos]) { pos = p->chain_[pos]) {
int64_t val;
int curr_length; int curr_length;
if (iter_cnt < 0) { if (iter_cnt < 0) {
if (iter_cnt < iter_min || best_val >= 0xff0000) { if (iter_cnt < iter_min || best_val >= 0xff0000) {
@ -166,10 +168,10 @@ static int HashChainFindCopy(const HashChain* const p,
} }
--iter_cnt; --iter_cnt;
if (best_length != 0 && if (best_length != 0 &&
argb[pos + best_length - 1] != argb[index + best_length - 1]) { argb[pos + best_length - 1] != argb_start[best_length - 1]) {
continue; continue;
} }
curr_length = FindMatchLength(argb + pos, argb + index, maxlen); curr_length = FindMatchLength(argb + pos, argb_start, maxlen);
if (curr_length < prev_length) { if (curr_length < prev_length) {
continue; continue;
} }