82 lines
2.5 KiB
C
82 lines
2.5 KiB
C
/*
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* Copyright (c) 2002-2003, Antonin Descampe
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS `AS IS'
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "raw.h"
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unsigned char raw_c; /* temporary buffer where bits are coded or decoded */
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unsigned int raw_ct; /* number of bits already read or free to write */
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unsigned int raw_lenmax; /* maximum length to decode */
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unsigned int raw_len; /* length decoded */
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unsigned char *raw_bp; /* pointer to the current position in the buffer */
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unsigned char *raw_start; /* pointer to the start of the buffer */
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unsigned char *raw_end; /* pointer to the end of the buffer */
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/*
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* Return the number of bytes already encoded.
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*/
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int raw_numbytes()
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{
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return raw_bp - raw_start;
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}
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/*
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* Initialize raw-decoder.
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*
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* bp : pointer to the start of the buffer from which the bytes will be read
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* len : length of the input buffer
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*/
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void raw_init_dec(unsigned char *bp, int len)
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{
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raw_start = bp;
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raw_lenmax = len;
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raw_len = 0;
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raw_c = 0;
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raw_ct = 0;
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}
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/*
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* Decode a symbol using raw-decoder. Cfr p.506 TAUBMAN
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*/
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int raw_decode()
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{
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int d;
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if (raw_ct == 0) {
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raw_ct = 8;
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if (raw_len == raw_lenmax)
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raw_c = 0xff;
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else {
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if (raw_c == 0xff)
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raw_ct = 7;
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raw_c = *(raw_start + raw_len);
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raw_len++;
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}
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}
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raw_ct--;
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d = (raw_c >> raw_ct) & 0x01;
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return d;
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}
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