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/* This file is part of libmspack.
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* (C) 2003-2004 Stuart Caie.
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* The Quantum method was created by David Stafford, adapted by Microsoft
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* libmspack is free software; you can redistribute it and/or modify it under
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* the terms of the GNU Lesser General Public License (LGPL) version 2.1
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* For further details, see the file COPYING.LIB distributed with libmspack
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#define MSPACK_QTM_H 1
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/* Quantum compression / decompression definitions */
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#define QTM_FRAME_SIZE (32768)
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struct qtmd_modelsym {
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unsigned short sym, cumfreq;
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int shiftsleft, entries;
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struct qtmd_modelsym *syms;
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struct mspack_system *sys; /* I/O routines */
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struct mspack_file *input; /* input file handle */
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struct mspack_file *output; /* output file handle */
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unsigned char *window; /* decoding window */
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unsigned int window_size; /* window size */
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unsigned int window_posn; /* decompression offset within window */
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unsigned int frame_start; /* start of current frame within window */
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unsigned short H, L, C; /* high/low/current: arith coding state */
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unsigned char header_read; /* have we started decoding a new frame? */
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unsigned char *inbuf, *i_ptr, *i_end, *o_ptr, *o_end;
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unsigned int bit_buffer, inbuf_size;
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unsigned char bits_left;
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/* four literal models, each representing 64 symbols
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* model0 for literals from 0 to 63 (selector = 0)
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* model1 for literals from 64 to 127 (selector = 1)
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* model2 for literals from 128 to 191 (selector = 2)
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* model3 for literals from 129 to 255 (selector = 3) */
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struct qtmd_model model0, model1, model2, model3;
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/* three match models.
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* model4 for match with fixed length of 3 bytes
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* model5 for match with fixed length of 4 bytes
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* model6 for variable length match, encoded with model6len model */
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struct qtmd_model model4, model5, model6, model6len;
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/* selector model. 0-6 to say literal (0,1,2,3) or match (4,5,6) */
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struct qtmd_model model7;
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/* symbol arrays for all models */
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struct qtmd_modelsym m0sym[64 + 1];
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struct qtmd_modelsym m1sym[64 + 1];
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struct qtmd_modelsym m2sym[64 + 1];
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struct qtmd_modelsym m3sym[64 + 1];
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struct qtmd_modelsym m4sym[24 + 1];
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struct qtmd_modelsym m5sym[36 + 1];
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struct qtmd_modelsym m6sym[42 + 1], m6lsym[27 + 1];
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struct qtmd_modelsym m7sym[7 + 1];
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/* allocates Quantum decompression state for decoding the given stream.
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* - returns NULL if window_bits is outwith the range 10 to 21 (inclusive).
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* - uses system->alloc() to allocate memory
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* - returns NULL if not enough memory
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* - window_bits is the size of the Quantum window, from 1Kb (10) to 2Mb (21).
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* - input_buffer_size is the number of bytes to use to store bitstream data.
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extern struct qtmd_stream *qtmd_init(struct mspack_system *system,
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struct mspack_file *input,
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struct mspack_file *output,
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int input_buffer_size);
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/* decompresses, or decompresses more of, a Quantum stream.
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* - out_bytes of data will be decompressed and the function will return
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* with an MSPACK_ERR_OK return code.
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* - decompressing will stop as soon as out_bytes is reached. if the true
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* amount of bytes decoded spills over that amount, they will be kept for
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* a later invocation of qtmd_decompress().
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* - the output bytes will be passed to the system->write() function given in
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* qtmd_init(), using the output file handle given in qtmd_init(). More
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* than one call may be made to system->write()
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* - Quantum will read input bytes as necessary using the system->read()
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* function given in qtmd_init(), using the input file handle given in
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* qtmd_init(). This will continue until system->read() returns 0 bytes,
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extern int qtmd_decompress(struct qtmd_stream *qtm, off_t out_bytes);
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/* frees all state associated with a Quantum data stream
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* - calls system->free() using the system pointer given in qtmd_init()
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void qtmd_free(struct qtmd_stream *qtm);
added
removed
libclamav/mspack/qtm.h
