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http://git.netsurf-browser.org/libnsgif.git/shortlog/fada1a850cb1e88b9c19e45029092311ab7f869c
...commit
http://git.netsurf-browser.org/libnsgif.git/commit/fada1a850cb1e88b9c19e45029092311ab7f869c
...tree
http://git.netsurf-browser.org/libnsgif.git/tree/fada1a850cb1e88b9c19e45029092311ab7f869c
The branch, tlsa/lzw-optimise has been updated
via fada1a850cb1e88b9c19e45029092311ab7f869c (commit)
from 9be2acf63d9f293d0ca1321dfd985889bce4e37d (commit)
Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.
- Log -----------------------------------------------------------------
commitdiff
http://git.netsurf-browser.org/libnsgif.git/commit/?id=fada1a850cb1e88b9c19e45029092311ab7f869c
commit fada1a850cb1e88b9c19e45029092311ab7f869c
Author: Michael Drake <[email protected]>
Commit: Michael Drake <[email protected]>
lzw: Optimisation: Pre-multiply relative offsets by struct size.
diff --git a/src/lzw.c b/src/lzw.c
index 59c74a6..fe79556 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->table_size - ctx->prev_code;
+ entry->extends = (ctx->table_size - ctx->prev_code) * sizeof(*entry);
ctx->table_size++;
}
@@ -444,6 +444,19 @@ static inline lzw_result lzw__decode(
}
/**
+ * Get the LZW table entry that the given entry extends.
+ *
+ * \param[in] entry The starting entry/
+ * \return new table entry.
+ */
+static inline const struct lzw_table_entry *lzw__entry_get_extends(
+ const struct lzw_table_entry *entry)
+{
+ return (const struct lzw_table_entry *)
+ (((const uint8_t *)(entry)) - entry->extends);
+}
+
+/**
* Write values for this code to the output stack.
*
* If there isn't enough space in the output stack, this function will write
@@ -483,13 +496,13 @@ 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--) {
- entry -= entry->extends;
+ entry = lzw__entry_get_extends(entry);
}
output_pos += count;
for (unsigned i = count; i != 0; i--) {
*--output_pos = entry->value;
- entry -= entry->extends;
+ entry = lzw__entry_get_extends(entry);
}
return count;
@@ -561,7 +574,7 @@ static inline uint32_t lzw__map_write_fn(struct lzw_ctx
*ctx,
ctx->output_left = left;
for (unsigned i = left; i != 0; i--) {
- entry -= entry->extends;
+ entry = lzw__entry_get_extends(entry);
}
output_pos += count;
@@ -571,12 +584,12 @@ static inline uint32_t lzw__map_write_fn(struct lzw_ctx
*ctx,
if (entry->value != ctx->transparency_idx) {
*output_pos = ctx->colour_map[entry->value];
}
- entry -= entry->extends;
+ entry = lzw__entry_get_extends(entry);
}
} else {
for (unsigned i = count; i != 0; i--) {
*--output_pos = ctx->colour_map[entry->value];
- entry -= entry->extends;
+ entry = lzw__entry_get_extends(entry);
}
}
-----------------------------------------------------------------------
Summary of changes:
src/lzw.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)
diff --git a/src/lzw.c b/src/lzw.c
index 59c74a6..fe79556 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->table_size - ctx->prev_code;
+ entry->extends = (ctx->table_size - ctx->prev_code) * sizeof(*entry);
ctx->table_size++;
}
@@ -444,6 +444,19 @@ static inline lzw_result lzw__decode(
}
/**
+ * Get the LZW table entry that the given entry extends.
+ *
+ * \param[in] entry The starting entry/
+ * \return new table entry.
+ */
+static inline const struct lzw_table_entry *lzw__entry_get_extends(
+ const struct lzw_table_entry *entry)
+{
+ return (const struct lzw_table_entry *)
+ (((const uint8_t *)(entry)) - entry->extends);
+}
+
+/**
* Write values for this code to the output stack.
*
* If there isn't enough space in the output stack, this function will write
@@ -483,13 +496,13 @@ 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--) {
- entry -= entry->extends;
+ entry = lzw__entry_get_extends(entry);
}
output_pos += count;
for (unsigned i = count; i != 0; i--) {
*--output_pos = entry->value;
- entry -= entry->extends;
+ entry = lzw__entry_get_extends(entry);
}
return count;
@@ -561,7 +574,7 @@ static inline uint32_t lzw__map_write_fn(struct lzw_ctx
*ctx,
ctx->output_left = left;
for (unsigned i = left; i != 0; i--) {
- entry -= entry->extends;
+ entry = lzw__entry_get_extends(entry);
}
output_pos += count;
@@ -571,12 +584,12 @@ static inline uint32_t lzw__map_write_fn(struct lzw_ctx
*ctx,
if (entry->value != ctx->transparency_idx) {
*output_pos = ctx->colour_map[entry->value];
}
- entry -= entry->extends;
+ entry = lzw__entry_get_extends(entry);
}
} else {
for (unsigned i = count; i != 0; i--) {
*--output_pos = ctx->colour_map[entry->value];
- entry -= entry->extends;
+ entry = lzw__entry_get_extends(entry);
}
}
--
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