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/**
* \file lzma/stream.h
* \brief .lzma Stream handling
*
* \author Copyright (C) 1999-2006 Igor Pavlov
* \author Copyright (C) 2007 Lasse Collin
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
#ifndef LZMA_H_INTERNAL
# error Never include this file directly. Use <lzma.h> instead.
#endif
/**
* \brief Options for .lzma Stream encoder
*/
typedef struct {
/**
* \brief Type of integrity Check
*
* The type of the integrity Check is stored into Stream Header
* and Stream Footer. The same Check is used for all Blocks in
* the Stream.
*/
lzma_check_type check;
/**
* \brief Precense of CRC32 of the Block Header
*
* Set this to true if CRC32 of every Block Header should be
* calculated and stored in the Block Header. This is recommended.
*
* This setting is stored into Stream Header and Stream Footer.
*/
lzma_bool has_crc32;
/**
* \brief Uncompressed Size in bytes
*
* This is somewhat advanced feature. Most users want to set this to
* LZMA_VLI_VALUE_UNKNOWN to indicate unknown Uncompressed Size.
*
* If the Uncompressed Size of the Stream being encoded is known,
* it can be stored to the beginning of the Stream. The details
* differ for Single-Block and Multi-Block Streams:
* - With Single-Block Streams, the Uncompressed Size is stored to
* the Block Header and End of Payload Marker is omitted.
* - With Multi-Block Streams, the Uncompressed Size is stored to
* the Header Metadata Block. The Uncompressed Size of the Blocks
* will be unknown, because liblzma cannot predict how the
* application is going to split the data in Blocks.
*/
lzma_vli uncompressed_size;
/**
* \brief Alignment of the beginning of the Stream
*
* Certain filters handle data in bigger chunks than single bytes.
* This affects two things:
* - Performance: aligned memory access is usually faster.
* - Further compression ratio in custom file formats: if you
* encode multiple Blocks with some non-compression filter
* such as LZMA_FILTER_POWERPC, it is a good idea to keep
* the inter-Block alignment correct to maximize compression
* ratio when all these Blocks are finally compressed as a
* single step.
*
* Usually the Stream is stored into its own file, thus
* the alignment is usually zero.
*/
uint32_t alignment;
/**
* \brief Array of filters used to encode Data Blocks
*
* There can be at maximum of seven filters. The end of the array is
* marked with .id = LZMA_VLI_VALUE_UNKNOWN. (That's why the array
* has eight members.) Minimum number of filters is zero; in that
* case, an implicit Copy filter is used.
*/
lzma_options_filter filters[8];
/**
* \brief Array of filters used to encode Metadata Blocks
*
* This is like filters[] but for Metadata Blocks. If Metadata
* Blocks are compressed, they usually are compressed with
* settings that require only little memory to uncompress e.g.
* LZMA with 64 KiB dictionary.
*
* \todo Recommend a preset.
*
* When liblzma sees that the Metadata Block would be very small
* even in uncompressed form, it is not compressed no matter
* what filter have been set here. This is to avoid possibly
* increasing the size of the Metadata Block with bad compression,
* and to avoid useless overhead of filters in uncompression phase.
*/
lzma_options_filter metadata_filters[8];
/**
* \brief Extra information in the Header Metadata Block
*/
const lzma_extra *header;
/**
* \brief Extra information in the Footer Metadata Block
*
* It is enough to set this pointer any time before calling
* lzma_code() with LZMA_FINISH as the second argument.
*/
const lzma_extra *footer;
} lzma_options_stream;
/**
* \brief Initializes Single-Block .lzma Stream encoder
*
* This is the function that most developers are looking for. :-) It
* compresses using the specified options without storing any extra
* information.
*
* \todo Describe that is_metadata is ignored, maybe something else.
*/
extern lzma_ret lzma_stream_encoder_single(
lzma_stream *strm, const lzma_options_stream *options);
/**
* \brief Initializes Multi-Block .lzma Stream encoder
*
*/
extern lzma_ret lzma_stream_encoder_multi(
lzma_stream *strm, const lzma_options_stream *options);
/**
* \brief Initializes decoder for .lzma Stream
*
* \param strm Pointer to propertily prepared lzma_stream
* \param header Pointer to hold a pointer to Extra Records read
* from the Header Metadata Block. Use NULL if
* you don't care about Extra Records.
* \param footer Same as header, but for Footer Metadata Block.
*
* \return - LZMA_OK: Initialization was successful.
* - LZMA_MEM_ERROR: Cannot allocate memory.
*
* If header and/or footer are not NULL, *header and/or *footer will be
* initially set to NULL.
*
* The application can detect that Header Metadata Block has been completely
* parsed when the decoder procudes some output the first time. If *header
* is still NULL, there was no Extra field in the Header Metadata Block (or
* the whole Header Metadata Block wasn't present at all).
*
* The application can detect that Footer Metadata Block has been parsed
* completely when lzma_code() returns LZMA_STREAM_END. If *footer is still
* NULL, there was no Extra field in the Footer Metadata Block.
*
* \note If you use lzma_memory_limitter, the Extra Records will be
* allocated with it, and thus remain in the lzma_memory_limitter
* even after they get exported to the application via *header
* and *footer pointers.
*/
extern lzma_ret lzma_stream_decoder(lzma_stream *strm,
lzma_extra **header, lzma_extra **footer);
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