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authorMichael Drake <tlsa@netsurf-browser.org>2021-04-04 22:27:52 +0100
committerMichael Drake <tlsa@netsurf-browser.org>2021-04-05 14:51:52 +0100
commit34d6277cf14fa104de5216fe156beab37d010d94 (patch)
tree0ce2397270ca256aa42c16fbbabc2e530313b687
parent28ee35e73ef56eefbe6992034a2b8046d343393b (diff)
downloadlibnsgif-34d6277cf14fa104de5216fe156beab37d010d94.tar.gz
libnsgif-34d6277cf14fa104de5216fe156beab37d010d94.tar.bz2
lzw: Add function for decoding multiple LZW codes at a time.
-rw-r--r--src/lzw.c26
-rw-r--r--src/lzw.h15
2 files changed, 41 insertions, 0 deletions
diff --git a/src/lzw.c b/src/lzw.c
index 6ac4d49..bd16aa1 100644
--- a/src/lzw.c
+++ b/src/lzw.c
@@ -437,3 +437,29 @@ lzw_result lzw_decode(struct lzw_ctx *ctx,
return lzw__decode(ctx, ctx->stack_base, sizeof(ctx->stack_base),
lzw__write_pixels, used);
}
+
+/* Exported function, documented in lzw.h */
+lzw_result lzw_decode_continuous(struct lzw_ctx *ctx,
+ const uint8_t ** const data,
+ uint32_t *used)
+{
+ *used = 0;
+ *data = ctx->stack_base;
+
+ if (ctx->output_left != 0) {
+ *used += lzw__write_pixels(ctx,
+ ctx->stack_base, sizeof(ctx->stack_base), *used,
+ ctx->output_code, ctx->output_left);
+ }
+
+ while (*used != sizeof(ctx->stack_base)) {
+ lzw_result res = lzw__decode(ctx,
+ ctx->stack_base, sizeof(ctx->stack_base),
+ lzw__write_pixels, used);
+ if (res != LZW_OK) {
+ return res;
+ }
+ }
+
+ return LZW_OK;
+}
diff --git a/src/lzw.h b/src/lzw.h
index dd0191e..c130c24 100644
--- a/src/lzw.h
+++ b/src/lzw.h
@@ -91,4 +91,19 @@ lzw_result lzw_decode(struct lzw_ctx *ctx,
const uint8_t *restrict *const restrict data,
uint32_t *restrict used);
+/**
+ * Read input codes until end of lzw context owned output buffer.
+ *
+ * Ensure anything in output is used before calling this, as anything
+ * on the there before this call will be trampled.
+ *
+ * \param[in] ctx LZW reading context, updated.
+ * \param[out] data Returns pointer to array of output values.
+ * \param[out] used Returns the number of values written to data.
+ * \return LZW_OK on success, or appropriate error code otherwise.
+ */
+lzw_result lzw_decode_continuous(struct lzw_ctx *ctx,
+ const uint8_t ** const data,
+ uint32_t *used);
+
#endif