dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2024-12-27 06:08:21 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

Update BackwardRefsWithLocalCache.

Browse Source 
Update BackwardRefsWithLocalCache to do in-place update of backward
references w.r.t local color cache index.

No impact on the compression density or compression speed.

Change-Id: Ie066251464c3928c044e037b43df3af28b48ca30
This commit is contained in:
Vikas Arora 2014-11-12 16:53:46 -08:00
parent d69e36ec59
commit 0f23566558
1 changed files with 11 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
src/enc/backward_references.c
View File

@ -817,39 +817,33 @@ static int CalculateBestCacheSize(const uint32_t* const argb,
int* const lz77_computed,
int* const best_cache_bits);
// Create the backward references for specified cache_bits from a source
// backward refs that is created without local color cache.
// Update (in-place) backward references for specified cache_bits.
static int BackwardRefsWithLocalCache(const uint32_t* const argb,
int cache_bits,
const VP8LBackwardRefs* const refs_src,
VP8LBackwardRefs* const refs_dst) {
VP8LBackwardRefs* const refs) {
int pixel_index = 0;
VP8LColorCache hashers;
VP8LRefsCursor c = VP8LRefsCursorInit(refs_src);
VP8LRefsCursor c = VP8LRefsCursorInit(refs);
if (!VP8LColorCacheInit(&hashers, cache_bits)) return 0;
ClearBackwardRefs(refs_dst);
while (VP8LRefsCursorOk(&c)) {
const PixOrCopy* const v_src = c.cur_pos;
if (PixOrCopyIsLiteral(v_src)) {
const uint32_t argb_literal = v_src->argb_or_distance;
PixOrCopy* const v = c.cur_pos;
if (PixOrCopyIsLiteral(v)) {
const uint32_t argb_literal = v->argb_or_distance;
if (VP8LColorCacheContains(&hashers, argb_literal)) {
const int ix = VP8LColorCacheGetIndex(&hashers, argb_literal);
BackwardRefsCursorAdd(refs_dst, PixOrCopyCreateCacheIdx(ix));
*v = PixOrCopyCreateCacheIdx(ix);
} else {
VP8LColorCacheInsert(&hashers, argb_literal);
BackwardRefsCursorAdd(refs_dst, *v_src);
}
++pixel_index;
} else {
// refs_src was created without local cache, so it can not have cache
// indexes.
// refs was created without local cache, so it can not have cache indexes.
int k;
assert(PixOrCopyIsCopy(v_src));
for (k = 0; k < v_src->len; ++k) {
assert(PixOrCopyIsCopy(v));
for (k = 0; k < v->len; ++k) {
VP8LColorCacheInsert(&hashers, argb[pixel_index++]);
}
BackwardRefsCursorAdd(refs_dst, *v_src);
}
VP8LRefsCursorNext(&c);
}
@ -877,13 +871,9 @@ VP8LBackwardRefs* VP8LGetBackwardReferences(
if (lz77_computed) {
// Transform refs_lz77 for the optimized cache_bits.
if (*cache_bits > 0) {
if (!BackwardRefsWithLocalCache(argb, *cache_bits, refs_lz77, refs_rle)) {
if (!BackwardRefsWithLocalCache(argb, *cache_bits, refs_lz77)) {
goto Error;
}
// Swap refs_lz77 and refs_rle.
best = refs_lz77;
refs_lz77 = refs_rle;
refs_rle = best;
}
} else {
if (!BackwardReferencesLz77(width, height, argb, *cache_bits, quality,