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/* This file is part of libmspack.
* (C) 2003-2013 Stuart Caie.
*
* The LZX method was created by Jonathan Forbes and Tomi Poutanen, adapted
* by Microsoft Corporation.
*
* libmspack is free software; you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License (LGPL) version 2.1
*
* For further details, see the file COPYING.LIB distributed with libmspack
*/
#ifndef MSPACK_LZX_H
#define MSPACK_LZX_H 1
#ifdef __cplusplus
extern "C" {
#endif
/* LZX compression / decompression definitions */
/* some constants defined by the LZX specification */
#define LZX_MIN_MATCH (2)
#define LZX_MAX_MATCH (257)
#define LZX_NUM_CHARS (256)
#define LZX_BLOCKTYPE_INVALID (0) /* also blocktypes 4-7 invalid */
#define LZX_BLOCKTYPE_VERBATIM (1)
#define LZX_BLOCKTYPE_ALIGNED (2)
#define LZX_BLOCKTYPE_UNCOMPRESSED (3)
#define LZX_PRETREE_NUM_ELEMENTS (20)
#define LZX_ALIGNED_NUM_ELEMENTS (8) /* aligned offset tree #elements */
#define LZX_NUM_PRIMARY_LENGTHS (7) /* this one missing from spec! */
#define LZX_NUM_SECONDARY_LENGTHS (249) /* length tree #elements */
/* LZX huffman defines: tweak tablebits as desired */
#define LZX_PRETREE_MAXSYMBOLS (LZX_PRETREE_NUM_ELEMENTS)
#define LZX_PRETREE_TABLEBITS (6)
#define LZX_MAINTREE_MAXSYMBOLS (LZX_NUM_CHARS + 290*8)
#define LZX_MAINTREE_TABLEBITS (12)
#define LZX_LENGTH_MAXSYMBOLS (LZX_NUM_SECONDARY_LENGTHS+1)
#define LZX_LENGTH_TABLEBITS (12)
#define LZX_ALIGNED_MAXSYMBOLS (LZX_ALIGNED_NUM_ELEMENTS)
#define LZX_ALIGNED_TABLEBITS (7)
#define LZX_LENTABLE_SAFETY (64) /* table decoding overruns are allowed */
#define LZX_FRAME_SIZE (32768) /* the size of a frame in LZX */
struct lzxd_stream {
struct mspack_system *sys; /* I/O routines */
struct mspack_file *input; /* input file handle */
struct mspack_file *output; /* output file handle */
off_t offset; /* number of bytes actually output */
off_t length; /* overall decompressed length of stream */
unsigned char *window; /* decoding window */
unsigned int window_size; /* window size */
unsigned int ref_data_size; /* LZX DELTA reference data size */
unsigned int num_offsets; /* number of match_offset entries in table */
unsigned int window_posn; /* decompression offset within window */
unsigned int frame_posn; /* current frame offset within in window */
unsigned int frame; /* the number of 32kb frames processed */
unsigned int reset_interval; /* which frame do we reset the compressor? */
unsigned int R0, R1, R2; /* for the LRU offset system */
unsigned int block_length; /* uncompressed length of this LZX block */
unsigned int block_remaining; /* uncompressed bytes still left to decode */
signed int intel_filesize; /* magic header value used for transform */
signed int intel_curpos; /* current offset in transform space */
unsigned char intel_started; /* has intel E8 decoding started? */
unsigned char block_type; /* type of the current block */
unsigned char header_read; /* have we started decoding at all yet? */
unsigned char input_end; /* have we reached the end of input? */
unsigned char is_delta; /* does stream follow LZX DELTA spec? */
int error;
/* I/O buffering */
unsigned char *inbuf, *i_ptr, *i_end, *o_ptr, *o_end;
unsigned int bit_buffer, bits_left, inbuf_size;
/* huffman code lengths */
unsigned char PRETREE_len [LZX_PRETREE_MAXSYMBOLS + LZX_LENTABLE_SAFETY];
unsigned char MAINTREE_len [LZX_MAINTREE_MAXSYMBOLS + LZX_LENTABLE_SAFETY];
unsigned char LENGTH_len [LZX_LENGTH_MAXSYMBOLS + LZX_LENTABLE_SAFETY];
unsigned char ALIGNED_len [LZX_ALIGNED_MAXSYMBOLS + LZX_LENTABLE_SAFETY];
/* huffman decoding tables */
unsigned short PRETREE_table [(1 << LZX_PRETREE_TABLEBITS) + |
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(LZX_PRETREE_MAXSYMBOLS * 2)]; |
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unsigned short MAINTREE_table[(1 << LZX_MAINTREE_TABLEBITS) + |
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(LZX_MAINTREE_MAXSYMBOLS * 2)]; |
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unsigned short LENGTH_table [(1 << LZX_LENGTH_TABLEBITS) + |
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(LZX_LENGTH_MAXSYMBOLS * 2)]; |
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unsigned short ALIGNED_table [(1 << LZX_ALIGNED_TABLEBITS) + |
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(LZX_ALIGNED_MAXSYMBOLS * 2)]; |
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unsigned char LENGTH_empty;
/* this is used purely for doing the intel E8 transform */
unsigned char e8_buf[LZX_FRAME_SIZE];
};
/**
* Allocates and initialises LZX decompression state for decoding an LZX
* stream.
*
* This routine uses system->alloc() to allocate memory. If memory
* allocation fails, or the parameters to this function are invalid,
* NULL is returned.
*
* @param system an mspack_system structure used to read from
* the input stream and write to the output
* stream, also to allocate and free memory.
* @param input an input stream with the LZX data.
* @param output an output stream to write the decoded data to.
* @param window_bits the size of the decoding window, which must be
* between 15 and 21 inclusive for regular LZX
* data, or between 17 and 25 inclusive for
* LZX DELTA data.
* @param reset_interval the interval at which the LZX bitstream is
* reset, in multiples of LZX frames (32678
* bytes), e.g. a value of 2 indicates the input
* stream resets after every 65536 output bytes.
* A value of 0 indicates that the bitstream never
* resets, such as in CAB LZX streams.
* @param input_buffer_size the number of bytes to use as an input
* bitstream buffer.
* @param output_length the length in bytes of the entirely
* decompressed output stream, if known in
* advance. It is used to correctly perform the
* Intel E8 transformation, which must stop 6
* bytes before the very end of the
* decompressed stream. It is not otherwise used
* or adhered to. If the full decompressed
* length is known in advance, set it here.
* If it is NOT known, use the value 0, and call
* lzxd_set_output_length() once it is
* known. If never set, 4 of the final 6 bytes
* of the output stream may be incorrect.
* @param is_delta should be zero for all regular LZX data,
* non-zero for LZX DELTA encoded data.
* @return a pointer to an initialised lzxd_stream structure, or NULL if
* there was not enough memory or parameters to the function were wrong.
*/
extern struct lzxd_stream *lzxd_init(struct mspack_system *system, |
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struct mspack_file *input,
struct mspack_file *output,
int window_bits,
int reset_interval,
int input_buffer_size,
off_t output_length, |
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char is_delta);
/* see description of output_length in lzxd_init() */
extern void lzxd_set_output_length(struct lzxd_stream *lzx, |
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off_t output_length); |
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/**
* Reads LZX DELTA reference data into the window and allows
* lzxd_decompress() to reference it.
*
* Call this before the first call to lzxd_decompress().
* @param lzx the LZX stream to apply this reference data to
* @param system an mspack_system implementation to use with the
* input param. Only read() will be called.
* @param input an input file handle to read reference data using
* system->read().
* @param length the length of the reference data. Cannot be longer
* than the LZX window size.
* @return an error code, or MSPACK_ERR_OK if successful
*/
extern int lzxd_set_reference_data(struct lzxd_stream *lzx,
struct mspack_system *system,
struct mspack_file *input,
unsigned int length);
/**
* Decompresses entire or partial LZX streams.
*
* The number of bytes of data that should be decompressed is given as the
* out_bytes parameter. If more bytes are decoded than are needed, they
* will be kept over for a later invocation.
*
* The output bytes will be passed to the system->write() function given in
* lzxd_init(), using the output file handle given in lzxd_init(). More than
* one call may be made to system->write().
* Input bytes will be read in as necessary using the system->read()
* function given in lzxd_init(), using the input file handle given in
* lzxd_init(). This will continue until system->read() returns 0 bytes,
* or an error. Errors will be passed out of the function as
* MSPACK_ERR_READ errors. Input streams should convey an "end of input
* stream" by refusing to supply all the bytes that LZX asks for when they
* reach the end of the stream, rather than return an error code.
*
* If any error code other than MSPACK_ERR_OK is returned, the stream
* should be considered unusable and lzxd_decompress() should not be
* called again on this stream.
*
* @param lzx LZX decompression state, as allocated by lzxd_init().
* @param out_bytes the number of bytes of data to decompress.
* @return an error code, or MSPACK_ERR_OK if successful
*/
extern int lzxd_decompress(struct lzxd_stream *lzx, off_t out_bytes);
/**
* Frees all state associated with an LZX data stream. This will call
* system->free() using the system pointer given in lzxd_init().
*
* @param lzx LZX decompression state to free.
*/
void lzxd_free(struct lzxd_stream *lzx);
#ifdef __cplusplus
}
#endif
#endif |