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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>
*/
#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_BAD_ICODE, /**< Error: Bad initial LZW code */
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.
*
* 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] minimum_code_size The LZW Minimum Code Size.
* \param[out] stack_base_out Returns base of decompressed data stack.
* \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 minimum_code_size);
/**
* Read a single LZW code and write into 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(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 *restrict used);
/**
* Read LZW codes into client buffer, mapping output to colours.
*
* Ensure anything in output is used before calling this, as anything
* on the there before this call will be trampled.
*
* 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 LZW reading context, updated.
* \param[in] transparency_idx Index representing transparency.
* \param[in] colour_map Index to pixel colour mapping
* \param[in] data Client buffer to fill with colour mapped values.
* \param[in] length Size of output array.
* \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_map_continuous(struct lzw_ctx *ctx,
uint32_t transparency_idx,
uint32_t *restrict colour_table,
uint32_t *restrict data,
uint32_t length,
uint32_t *restrict used);
#endif
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