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...log
http://git.netsurf-browser.org/libnsgif.git/shortlog/9be2acf63d9f293d0ca1321dfd985889bce4e37d
...commit
http://git.netsurf-browser.org/libnsgif.git/commit/9be2acf63d9f293d0ca1321dfd985889bce4e37d
...tree
http://git.netsurf-browser.org/libnsgif.git/tree/9be2acf63d9f293d0ca1321dfd985889bce4e37d
The branch, tlsa/lzw-optimise has been created
at 9be2acf63d9f293d0ca1321dfd985889bce4e37d (commit)
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commitdiff
http://git.netsurf-browser.org/libnsgif.git/commit/?id=9be2acf63d9f293d0ca1321dfd985889bce4e37d
commit 9be2acf63d9f293d0ca1321dfd985889bce4e37d
Author: Michael Drake <[email protected]>
Commit: Michael Drake <[email protected]>
lzw: Use relative offset to next output entry, rather than absolute.
diff --git a/src/lzw.c b/src/lzw.c
index 710895e..59c74a6 100644
--- a/src/lzw.c
+++ b/src/lzw.c
@@ -364,7 +364,7 @@ static inline void lzw__table_add_entry(
entry->value = code;
entry->first = ctx->prev_code_first;
entry->count = ctx->prev_code_count + 1;
- entry->extends = ctx->prev_code;
+ entry->extends = ctx->table_size - ctx->prev_code;
ctx->table_size++;
}
@@ -467,7 +467,7 @@ static inline uint32_t lzw__write_fn(struct lzw_ctx *ctx,
uint16_t left)
{
uint8_t *restrict output_pos = (uint8_t *)output_data + output_used;
- const struct lzw_table_entry * const table = ctx->table;
+ const struct lzw_table_entry *entry = ctx->table + code;
uint32_t space = output_length - output_used;
uint16_t count = left;
@@ -483,15 +483,13 @@ static inline uint32_t lzw__write_fn(struct lzw_ctx *ctx,
/* Skip over any values we don't have space for. */
for (unsigned i = left; i != 0; i--) {
- const struct lzw_table_entry *entry = table + code;
- code = entry->extends;
+ entry -= entry->extends;
}
output_pos += count;
for (unsigned i = count; i != 0; i--) {
- const struct lzw_table_entry *entry = table + code;
*--output_pos = entry->value;
- code = entry->extends;
+ entry -= entry->extends;
}
return count;
@@ -548,7 +546,7 @@ static inline uint32_t lzw__map_write_fn(struct lzw_ctx
*ctx,
uint16_t left)
{
uint32_t *restrict output_pos = (uint32_t *)output_data + output_used;
- const struct lzw_table_entry * const table = ctx->table;
+ const struct lzw_table_entry *entry = ctx->table + code;
uint32_t space = output_length - output_used;
uint16_t count = left;
@@ -563,25 +561,22 @@ static inline uint32_t lzw__map_write_fn(struct lzw_ctx
*ctx,
ctx->output_left = left;
for (unsigned i = left; i != 0; i--) {
- const struct lzw_table_entry *entry = table + code;
- code = entry->extends;
+ entry -= entry->extends;
}
output_pos += count;
if (ctx->has_transparency) {
for (unsigned i = count; i != 0; i--) {
- const struct lzw_table_entry *entry = table + code;
--output_pos;
if (entry->value != ctx->transparency_idx) {
*output_pos = ctx->colour_map[entry->value];
}
- code = entry->extends;
+ entry -= entry->extends;
}
} else {
for (unsigned i = count; i != 0; i--) {
- const struct lzw_table_entry *entry = table + code;
*--output_pos = ctx->colour_map[entry->value];
- code = entry->extends;
+ entry -= entry->extends;
}
}
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