diff options
Diffstat (limited to 'src/lzw.c')
| -rw-r--r-- | src/lzw.c | 47 |
1 files changed, 35 insertions, 12 deletions
@@ -241,8 +241,7 @@ lzw_result lzw_decode_init( const uint8_t *compressed_data, uint32_t compressed_data_len, uint32_t compressed_data_pos, - uint8_t minimum_code_size, - const uint8_t ** const stack_base_out) + uint8_t minimum_code_size) { struct lzw_table_entry *table = ctx->table; @@ -274,7 +273,6 @@ lzw_result lzw_decode_init( lzw__clear_table(ctx); ctx->prev_code = ctx->clear_code; - *stack_base_out = ctx->stack_base; return LZW_OK; } @@ -301,30 +299,45 @@ static inline void lzw__table_add_entry( /** * Write values for this code to the output stack. * - * \param[in] ctx LZW reading context, updated. - * \param[in] code LZW code to output values for. + * \param[in] ctx LZW reading context, updated. + * \param[in] output Array to write output values into. + * \param[in] code LZW code to output values for. * \return Number of pixel values written. */ static inline uint32_t lzw__write_pixels(struct lzw_ctx *ctx, + void *restrict output, uint32_t code) { - uint8_t *stack_pos = ctx->stack_base; + uint8_t *restrict output_pos = (uint8_t *)output; struct lzw_table_entry * const table = ctx->table; uint32_t count = table[code].count; - stack_pos += count; + output_pos += count; for (unsigned i = count; i != 0; i--) { struct lzw_table_entry *entry = table + code; - *--stack_pos = entry->value; + *--output_pos = entry->value; code = entry->extends; } return count; } -/* Exported function, documented in lzw.h */ -lzw_result lzw_decode(struct lzw_ctx *ctx, - uint32_t *written) +/** + * Fill the LZW stack with decompressed data + * + * 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[in] output Array to write output values into. + * \param[out] used Returns the number of values written. + * Use with `stack_base_out` value from previous + * lzw_decode_init() call. + * \return LZW_OK on success, or appropriate error code otherwise. + */ +static inline lzw_result lzw__decode(struct lzw_ctx *ctx, + uint8_t *restrict output, + uint32_t *restrict used) { lzw_result res; uint32_t code; @@ -362,7 +375,7 @@ lzw_result lzw_decode(struct lzw_ctx *ctx, } } - *written += lzw__write_pixels(ctx, code); + *used += lzw__write_pixels(ctx, output, code); } /* Store details of this code as "previous code" to the context. */ @@ -372,3 +385,13 @@ lzw_result lzw_decode(struct lzw_ctx *ctx, return LZW_OK; } + +/* Exported function, documented in lzw.h */ +lzw_result lzw_decode(struct lzw_ctx *ctx, + const uint8_t *restrict* const restrict data, + uint32_t *restrict used) +{ + *used = 0; + *data = ctx->stack_base; + return lzw__decode(ctx, ctx->stack_base, used); +} |