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/*
* This file is part of NetSurf's LibNSGIF, http://www.netsurf-browser.org/
* Licensed under the MIT License,
* http://www.opensource.org/licenses/mit-license.php
*
* Copyright 2017 Michael Drake <michael.drake@codethink.co.uk>
* Copyright 2021 Michael Drake <tlsa@netsurf-browser.org>
*/
#ifndef LZW_H_
#define LZW_H_
/**
* \file
* \brief LZW decompression (interface)
*
* Decoder for GIF LZW data.
*/
/** Maximum LZW code size in bits */
#define LZW_CODE_MAX 12
/* Declare lzw internal context structure */
struct lzw_ctx;
/** LZW decoding response codes */
typedef enum lzw_result {
LZW_OK, /**< Success */
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_NO_COLOUR, /**< Error: No colour map provided. */
LZW_BAD_ICODE, /**< Error: Bad initial LZW code */
LZW_BAD_PARAM, /**< Error: Bad function parameter. */
LZW_BAD_CODE, /**< Error: Bad LZW code */
} lzw_result;
/**
* Create an LZW decompression context.
*
* \param[out] ctx Returns an LZW decompression context. Caller owned,
* free with lzw_context_destroy().
* \return LZW_OK on success, or appropriate error code otherwise.
*/
lzw_result lzw_context_create(
struct lzw_ctx **ctx);
/**
* Destroy an LZW decompression context.
*
* \param[in] ctx The LZW decompression context to destroy.
*/
void lzw_context_destroy(
struct lzw_ctx *ctx);
/**
* Initialise an LZW decompression context for decoding.
*
* \param[in] ctx The LZW decompression context to initialise.
* \param[in] minimum_code_size The LZW Minimum Code Size.
* \param[in] input_data The compressed data.
* \param[in] input_length Byte length of compressed data.
* \param[in] input_pos Start position in data. Must be position
* of a size byte at sub-block start.
* \return LZW_OK on success, or appropriate error code otherwise.
*/
lzw_result lzw_decode_init(
struct lzw_ctx *ctx,
uint8_t minimum_code_size,
const uint8_t *input_data,
uint32_t input_length,
uint32_t input_pos);
/**
* Read input codes until end of LZW context owned output buffer.
*
* Ensure anything in output is used before calling this, as anything
* there before this call will be trampled.
*
* \param[in] ctx LZW reading context, updated.
* \param[out] output_data Returns pointer to array of output values.
* \param[out] output_written Returns the number of values written to data.
* \return LZW_OK on success, or appropriate error code otherwise.
*/
lzw_result lzw_decode(struct lzw_ctx *ctx,
const uint8_t *restrict *const restrict output_data,
uint32_t *restrict output_written);
/**
* Initialise an LZW decompression context for decoding to colour map values.
*
* For transparency to work correctly, the given client buffer must have
* the values from the previous frame. The transparency_idx should be a value
* of 256 or above, if the frame does not have transparency.
*
* \param[in] ctx The LZW decompression context to initialise.
* \param[in] minimum_code_size The LZW Minimum Code Size.
* \param[in] transparency_idx Index representing transparency.
* \param[in] colour_table Index to pixel colour mapping.
* \param[in] input_data The compressed data.
* \param[in] input_length Byte length of compressed data.
* \param[in] input_pos Start position in data. Must be position
* of a size byte at sub-block start.
* \return LZW_OK on success, or appropriate error code otherwise.
*/
lzw_result lzw_decode_init_map(
struct lzw_ctx *ctx,
uint8_t minimum_code_size,
uint32_t transparency_idx,
const uint32_t *colour_table,
const uint8_t *input_data,
uint32_t input_length,
uint32_t input_pos);
/**
* Read LZW codes into client buffer, mapping output to colours.
*
* The context must have been initialised using \ref lzw_decode_init_map
* before calling this function, in order to provide the colour mapping table
* and any transparency index.
*
* Ensure anything in output is used before calling this, as anything
* there before this call will be trampled.
*
* \param[in] ctx LZW reading context, updated.
* \param[in] output_data Client buffer to fill with colour mapped values.
* \param[in] output_length Size of output array.
* \param[out] output_written Returns the number of values written to data.
* \return LZW_OK on success, or appropriate error code otherwise.
*/
lzw_result lzw_decode_map(struct lzw_ctx *ctx,
uint32_t *restrict output_data,
uint32_t output_length,
uint32_t *restrict output_written);
#endif
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