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Lossless decoder fix for a special transform order

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Fix the lossless decoder for the case when it has to apply other
inverse transforms before applying Color indexing inverse transform.

The main idea is to make ColorIndexingInverse virtually in-place: we
use the fact that the argb_cache is allocated to accommodate all
*unpacked* pixels of a macro-row, not just *packed* pixels.

Change-Id: I27f11f3043f863dfd753cc2580bc5b36376800c4
This commit is contained in:
Urvang Joshi
2012-08-09 02:44:38 +05:30
committed by Gerrit Code Review
parent 62dd9bb242
commit a0a488554d
2 changed files with 23 additions and 7 deletions
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14
src/dec/vp8l.c
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@ -615,20 +615,22 @@ static WEBP_INLINE HTreeGroup* GetHtreeGroupForPos(VP8LMetadata* const hdr,
typedef void (*ProcessRowsFunc)(VP8LDecoder* const dec, int row);
static void ApplyTransforms(VP8LDecoder* const dec, int num_rows,
static void ApplyInverseTransforms(VP8LDecoder* const dec, int num_rows,
const uint32_t* const rows) {
int n = dec->next_transform_;
const int cache_pixs = dec->width_ * num_rows;
uint32_t* rows_data = dec->argb_cache_;
const int start_row = dec->last_row_;
const int end_row = start_row + num_rows;
const uint32_t* rows_in = rows;
uint32_t* const rows_out = dec->argb_cache_;
// Inverse transforms.
// TODO: most transforms only need to operate on the cropped region only.
memcpy(rows_data, rows, cache_pixs * sizeof(*rows_data));
memcpy(rows_out, rows_in, cache_pixs * sizeof(*rows_out));
while (n-- > 0) {
VP8LTransform* const transform = &dec->transforms_[n];
VP8LInverseTransform(transform, start_row, end_row, rows, rows_data);
VP8LInverseTransform(transform, start_row, end_row, rows_in, rows_out);
rows_in = rows_out;
}
}
@ -639,7 +641,7 @@ static void ProcessRows(VP8LDecoder* const dec, int row) {
const int num_rows = row - dec->last_row_;
if (num_rows <= 0) return; // Nothing to be done.
ApplyTransforms(dec, num_rows, rows);
ApplyInverseTransforms(dec, num_rows, rows);
// Emit output.
{
@ -1066,7 +1068,7 @@ static void ExtractAlphaRows(VP8LDecoder* const dec, int row) {
const uint32_t* const in = dec->argb_ + dec->width_ * dec->last_row_;
if (num_rows <= 0) return; // Nothing to be done.
ApplyTransforms(dec, num_rows, in);
ApplyInverseTransforms(dec, num_rows, in);
// Extract alpha (which is stored in the green plane).
{