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author | Michael Drake <michael.drake@codethink.co.uk> | 2017-04-03 10:14:25 +0100 |
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committer | Michael Drake <michael.drake@codethink.co.uk> | 2017-04-05 11:06:23 +0100 |
commit | 86ebd63cc1e9570cf247da26635375e31fc57d40 (patch) | |
tree | f214edddb90d031d37e96f3adbeb39119ad35429 /src/lzw.h | |
parent | 960c3b6d2229dcc7cc4a4ef60838329b78880e66 (diff) | |
download | libnsgif-86ebd63cc1e9570cf247da26635375e31fc57d40.tar.gz libnsgif-86ebd63cc1e9570cf247da26635375e31fc57d40.tar.bz2 |
New LZW decoder: Add client calls to initialise LZW, and perform decode.
Diffstat (limited to 'src/lzw.h')
-rw-r--r-- | src/lzw.h | 54 |
1 files changed, 54 insertions, 0 deletions
@@ -17,6 +17,10 @@ */ +/** Maximum LZW code size in bits */ +#define LZW_CODE_MAX 12 + + /* Declare lzw internal context structure */ struct lzw_ctx; @@ -27,6 +31,10 @@ typedef enum lzw_result { LZW_OK_EOD, /**< Success; reached zero-length sub-block */ LZW_NO_MEM, /**< Error: Out of memory */ LZW_NO_DATA, /**< Error: Out of data */ + LZW_EOI_CODE, /**< Error: End of Information code */ + LZW_BAD_ICODE, /**< Error: Bad initial LZW code */ + LZW_BAD_CODE, /**< Error: Bad LZW code */ + LZW_BAD_DATA, /**< Error: Bad data */ } lzw_result; @@ -48,5 +56,51 @@ lzw_result lzw_context_create( void lzw_context_destroy( struct lzw_ctx *ctx); +/** + * Initialise an LZW decompression context for decoding. + * + * Caller owns neither `stack_base_out` or `stack_pos_out`. + * + * \param[in] ctx The LZW decompression context to initialise. + * \param[in] compressed_data The compressed data. + * \param[in] compressed_data_len Byte length of compressed data. + * \param[in] compressed_data_pos Start position in data. Must be position + * of a size byte at sub-block start. + * \param[in] code_size The initial LZW code size to use. + * \param[out] stack_base_out Returns base of decompressed data stack. + * \param[out] stack_pos_out Returns current stack position. + * There are `stack_pos_out - stack_base_out` + * current stack entries. + * \return LZW_OK on success, or appropriate error code otherwise. + */ +lzw_result lzw_decode_init( + struct lzw_ctx *ctx, + const uint8_t *compressed_data, + uint32_t compressed_data_len, + uint32_t compressed_data_pos, + uint8_t code_size, + const uint8_t ** const stack_base_out, + const uint8_t ** const stack_pos_out); + +/** + * Fill the LZW stack with decompressed data + * + * Ensure anything on the stack is used before calling this, as anything + * on the stack before this call will be trampled. + * + * Caller does not own `stack_pos_out`. + * + * \param[in] ctx LZW reading context, updated. + * \param[out] stack_pos_out Returns current stack position. + * Use with `stack_base_out` value from previous + * lzw_decode_init() call. + * There are `stack_pos_out - stack_base_out` + * current stack entries. + * \return LZW_OK on success, or appropriate error code otherwise. + */ +lzw_result lzw_decode( + struct lzw_ctx *ctx, + const uint8_t ** const stack_pos_out); + #endif |