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/*
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* SpanDSP - a series of DSP components for telephony
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*
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* v42bis.c
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*
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* Written by Steve Underwood <steveu@coppice.org>
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*
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* Copyright (C) 2005 Steve Underwood
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License version 2.1,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id: v42bis.c,v 1.37 2009/02/10 13:06:47 steveu Exp $
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*/
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/* THIS IS A WORK IN PROGRESS. IT IS NOT FINISHED.
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Currently it performs the core compression and decompression functions OK.
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However, a number of the bells and whistles in V.42bis are incomplete. */
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/*! \file */
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#if defined(HAVE_CONFIG_H)
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#include "config.h"
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <inttypes.h>
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#include <string.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <ctype.h>
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#include <assert.h>
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#include "spandsp/telephony.h"
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#include "spandsp/logging.h"
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#include "spandsp/bit_operations.h"
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#include "spandsp/v42bis.h"
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#include "spandsp/private/logging.h"
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#include "spandsp/private/v42bis.h"
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/* Fixed parameters from the spec. */
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#define V42BIS_N3 8 /* Character size (bits) */
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#define V42BIS_N4 256 /* Number of characters in the alphabet */
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#define V42BIS_N5 (V42BIS_N4 + V42BIS_N6) /* Index number of first dictionary entry used to store a string */
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#define V42BIS_N6 3 /* Number of control codewords */
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/* Control code words in compressed mode */
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enum
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{
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V42BIS_ETM = 0, /* Enter transparent mode */
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V42BIS_FLUSH = 1, /* Flush data */
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V42BIS_STEPUP = 2 /* Step up codeword size */
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};
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/* Command codes in transparent mode */
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enum
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{
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V42BIS_ECM = 0, /* Enter compression mode */
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V42BIS_EID = 1, /* Escape character in data */
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V42BIS_RESET = 2 /* Force reinitialisation */
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};
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static __inline__ void push_compressed_raw_octet(v42bis_compress_state_t *ss, int octet)
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{
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ss->output_buf[ss->output_octet_count++] = (uint8_t) octet;
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if (ss->output_octet_count >= ss->max_len)
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{
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ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
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ss->output_octet_count = 0;
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}
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}
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/*- End of function --------------------------------------------------------*/
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static __inline__ void push_compressed_code(v42bis_compress_state_t *ss, int code)
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{
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ss->output_bit_buffer |= code << (32 - ss->v42bis_parm_c2 - ss->output_bit_count);
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ss->output_bit_count += ss->v42bis_parm_c2;
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while (ss->output_bit_count >= 8)
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{
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push_compressed_raw_octet(ss, ss->output_bit_buffer >> 24);
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ss->output_bit_buffer <<= 8;
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ss->output_bit_count -= 8;
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}
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}
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/*- End of function --------------------------------------------------------*/
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static __inline__ void push_compressed_octet(v42bis_compress_state_t *ss, int code)
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{
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ss->output_bit_buffer |= code << (32 - 8 - ss->output_bit_count);
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ss->output_bit_count += 8;
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while (ss->output_bit_count >= 8)
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{
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push_compressed_raw_octet(ss, ss->output_bit_buffer >> 24);
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ss->output_bit_buffer <<= 8;
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ss->output_bit_count -= 8;
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}
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}
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/*- End of function --------------------------------------------------------*/
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int v42bis_compress(v42bis_state_t *s, const uint8_t *buf, int len)
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{
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int ptr;
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int i;
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uint32_t octet;
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uint32_t code;
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v42bis_compress_state_t *ss;
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ss = &s->compress;
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if ((s->v42bis_parm_p0 & 2) == 0)
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{
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/* Compression is off - just push the incoming data out */
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for (i = 0; i < len - ss->max_len; i += ss->max_len)
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ss->handler(ss->user_data, buf + i, ss->max_len);
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if (i < len)
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ss->handler(ss->user_data, buf + i, len - i);
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return 0;
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}
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ptr = 0;
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if (ss->first && len > 0)
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{
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octet = buf[ptr++];
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ss->string_code = octet + V42BIS_N6;
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if (ss->transparent)
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push_compressed_octet(ss, octet);
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ss->first = FALSE;
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}
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while (ptr < len)
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{
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octet = buf[ptr++];
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if ((ss->dict[ss->string_code].children[octet >> 5] & (1 << (octet & 0x1F))))
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{
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/* The leaf exists. Now find it in the table. */
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/* TODO: This is a brute force scan for a match. We need something better. */
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for (code = 0; code < ss->v42bis_parm_c3; code++)
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{
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if (ss->dict[code].parent_code == ss->string_code && ss->dict[code].node_octet == octet)
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break;
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}
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}
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else
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{
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/* The leaf does not exist. */
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code = s->v42bis_parm_n2;
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}
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/* 6.3(b) If the string matches a dictionary entry, and the entry is not that entry
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created by the last invocation of the string matching procedure, then the
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next character shall be read and appended to the string and this step
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repeated. */
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if (code < ss->v42bis_parm_c3 && code != ss->latest_code)
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{
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/* The string was found */
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ss->string_code = code;
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ss->string_length++;
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}
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else
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{
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/* The string is not in the table. */
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if (!ss->transparent)
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{
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/* 7.4 Encoding - we now have the longest matchable string, and will need to output the code for it. */
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while (ss->v42bis_parm_c1 >= ss->v42bis_parm_c3 && ss->v42bis_parm_c3 <= s->v42bis_parm_n2)
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{
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/* We need to increase the codeword size */
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/* 7.4(a) */
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push_compressed_code(ss, V42BIS_STEPUP);
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/* 7.4(b) */
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ss->v42bis_parm_c2++;
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/* 7.4(c) */
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ss->v42bis_parm_c3 <<= 1;
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/* 7.4(d) this might need to be repeated, so we loop */
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}
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/* 7.5 Transfer - output the last state of the string */
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push_compressed_code(ss, ss->string_code);
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}
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/* 7.6 Dictionary updating */
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/* 6.4 Add the string to the dictionary */
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/* 6.4(b) The string is not in the table. */
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if (code != ss->latest_code && ss->string_length < s->v42bis_parm_n7)
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{
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ss->latest_code = ss->v42bis_parm_c1;
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/* 6.4(a) The length of the string is in range for adding to the dictionary */
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/* If the last code was a leaf, it no longer is */
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ss->dict[ss->string_code].leaves++;
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ss->dict[ss->string_code].children[octet >> 5] |= (1 << (octet & 0x1F));
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/* The new one is definitely a leaf */
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ss->dict[ss->v42bis_parm_c1].parent_code = (uint16_t) ss->string_code;
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ss->dict[ss->v42bis_parm_c1].leaves = 0;
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ss->dict[ss->v42bis_parm_c1].node_octet = (uint8_t) octet;
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/* 7.7 Node recovery */
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/* 6.5 Recovering a dictionary entry to use next */
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for (;;)
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{
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/* 6.5(a) and (b) */
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if ((int) (++ss->v42bis_parm_c1) >= s->v42bis_parm_n2)
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ss->v42bis_parm_c1 = V42BIS_N5;
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/* 6.5(c) We need to reuse a leaf node */
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if (ss->dict[ss->v42bis_parm_c1].leaves)
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continue;
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if (ss->dict[ss->v42bis_parm_c1].parent_code == 0xFFFF)
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break;
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/* 6.5(d) Detach the leaf node from its parent, and re-use it */
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/* Possibly make the parent a leaf node again */
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ss->dict[ss->dict[ss->v42bis_parm_c1].parent_code].leaves--;
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ss->dict[ss->dict[ss->v42bis_parm_c1].parent_code].children[ss->dict[ss->v42bis_parm_c1].node_octet >> 5] &= ~(1 << (ss->dict[ss->v42bis_parm_c1].node_octet & 0x1F));
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ss->dict[ss->v42bis_parm_c1].parent_code = 0xFFFF;
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break;
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}
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}
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else
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{
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ss->latest_code = 0xFFFFFFFF;
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}
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/* 7.8 Data compressibility test */
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/* Filter on the balance of what went into the compressor, and what came out */
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ss->compressibility_filter += ((((8*ss->string_length - ss->v42bis_parm_c2) << 20) - ss->compressibility_filter) >> 10);
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if (ss->compression_mode == V42BIS_COMPRESSION_MODE_DYNAMIC)
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{
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/* Work out if it is appropriate to change between transparent and
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compressed mode. */
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if (ss->transparent)
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{
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if (ss->compressibility_filter > 0)
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{
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if (++ss->compressibility_persistence > 1000)
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{
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/* Schedule a switch to compressed mode */
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ss->change_transparency = -1;
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ss->compressibility_persistence = 0;
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}
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}
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else
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{
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ss->compressibility_persistence = 0;
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}
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}
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else
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{
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if (ss->compressibility_filter < 0)
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{
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if (++ss->compressibility_persistence > 1000)
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{
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/* Schedule a switch to transparent mode */
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ss->change_transparency = 1;
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ss->compressibility_persistence = 0;
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}
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}
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else
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{
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ss->compressibility_persistence = 0;
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}
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}
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}
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if (ss->change_transparency)
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{
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if (ss->change_transparency < 0)
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{
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if (ss->transparent)
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{
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printf("Going compressed\n");
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/* 7.8.1 Transition to compressed mode */
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/* Switch out of transparent now, between codes. We need to send the octet which did not
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match, just before switching. */
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if (octet == ss->escape_code)
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{
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push_compressed_octet(ss, ss->escape_code++);
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push_compressed_octet(ss, V42BIS_EID);
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}
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else
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{
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push_compressed_octet(ss, octet);
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}
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push_compressed_octet(ss, ss->escape_code++);
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push_compressed_octet(ss, V42BIS_ECM);
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ss->transparent = FALSE;
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}
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}
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else
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{
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if (!ss->transparent)
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{
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printf("Going transparent\n");
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/* 7.8.2 Transition to transparent mode */
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/* Switch into transparent now, between codes, and the unmatched octet should
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go out in transparent mode, just below */
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push_compressed_code(ss, V42BIS_ETM);
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ss->transparent = TRUE;
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}
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}
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ss->change_transparency = 0;
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}
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/* 7.8.3 Reset function - TODO */
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ss->string_code = octet + V42BIS_N6;
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ss->string_length = 1;
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}
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if (ss->transparent)
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{
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if (octet == ss->escape_code)
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{
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push_compressed_octet(ss, ss->escape_code++);
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push_compressed_octet(ss, V42BIS_EID);
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}
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else
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{
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push_compressed_octet(ss, octet);
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}
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}
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}
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return 0;
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}
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/*- End of function --------------------------------------------------------*/
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int v42bis_compress_flush(v42bis_state_t *s)
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{
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v42bis_compress_state_t *ss;
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ss = &s->compress;
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if (!ss->transparent)
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{
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/* Output the last state of the string */
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push_compressed_code(ss, ss->string_code);
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/* TODO: We use a positive FLUSH at all times. It is really needed, if the
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previous step resulted in no leftover bits. */
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push_compressed_code(ss, V42BIS_FLUSH);
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}
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while (ss->output_bit_count > 0)
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{
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push_compressed_raw_octet(ss, ss->output_bit_buffer >> 24);
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ss->output_bit_buffer <<= 8;
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ss->output_bit_count -= 8;
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}
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/* Now push out anything remaining. */
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if (ss->output_octet_count > 0)
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{
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348
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ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
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ss->output_octet_count = 0;
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}
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return 0;
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}
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/*- End of function --------------------------------------------------------*/
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354
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#if 0
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int v42bis_compress_dump(v42bis_state_t *s)
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{
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358
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int i;
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359
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for (i = 0; i < V42BIS_MAX_CODEWORDS; i++)
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{
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if (s->compress.dict[i].parent_code != 0xFFFF)
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{
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printf("Entry %4x, prior %4x, leaves %d, octet %2x\n", i, s->compress.dict[i].parent_code, s->compress.dict[i].leaves, s->compress.dict[i].node_octet);
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365
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}
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}
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return 0;
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}
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369
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/*- End of function --------------------------------------------------------*/
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#endif
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371
|
|
372
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int v42bis_decompress(v42bis_state_t *s, const uint8_t *buf, int len)
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373
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{
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374
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int ptr;
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375
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int i;
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376
|
int this_length;
|
377
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uint8_t *string;
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378
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uint32_t code;
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379
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uint32_t new_code;
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int code_len;
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381
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v42bis_decompress_state_t *ss;
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uint8_t decode_buf[V42BIS_MAX_STRING_SIZE];
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383
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|
384
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ss = &s->decompress;
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if ((s->v42bis_parm_p0 & 1) == 0)
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386
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{
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387
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/* Compression is off - just push the incoming data out */
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for (i = 0; i < len - ss->max_len; i += ss->max_len)
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ss->handler(ss->user_data, buf + i, ss->max_len);
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390
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if (i < len)
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ss->handler(ss->user_data, buf + i, len - i);
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return 0;
|
393
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}
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394
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ptr = 0;
|
395
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code_len = (ss->transparent) ? 8 : ss->v42bis_parm_c2;
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396
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for (;;)
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{
|
398
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/* Fill up the bit buffer. */
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399
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while (ss->input_bit_count < 32 - 8 && ptr < len)
|
400
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{
|
401
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ss->input_bit_count += 8;
|
402
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ss->input_bit_buffer |= (uint32_t) buf[ptr++] << (32 - ss->input_bit_count);
|
403
|
}
|
404
|
if (ss->input_bit_count < code_len)
|
405
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break;
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406
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new_code = ss->input_bit_buffer >> (32 - code_len);
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407
|
ss->input_bit_count -= code_len;
|
408
|
ss->input_bit_buffer <<= code_len;
|
409
|
if (ss->transparent)
|
410
|
{
|
411
|
code = new_code;
|
412
|
if (ss->escaped)
|
413
|
{
|
414
|
ss->escaped = FALSE;
|
415
|
if (code == V42BIS_ECM)
|
416
|
{
|
417
|
printf("Hit V42BIS_ECM\n");
|
418
|
ss->transparent = FALSE;
|
419
|
code_len = ss->v42bis_parm_c2;
|
420
|
}
|
421
|
else if (code == V42BIS_EID)
|
422
|
{
|
423
|
printf("Hit V42BIS_EID\n");
|
424
|
ss->output_buf[ss->output_octet_count++] = ss->escape_code - 1;
|
425
|
if (ss->output_octet_count >= ss->max_len - s->v42bis_parm_n7)
|
426
|
{
|
427
|
ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
|
428
|
ss->output_octet_count = 0;
|
429
|
}
|
430
|
}
|
431
|
else if (code == V42BIS_RESET)
|
432
|
{
|
433
|
printf("Hit V42BIS_RESET\n");
|
434
|
}
|
435
|
else
|
436
|
{
|
437
|
printf("Hit V42BIS_???? - %" PRIu32 "\n", code);
|
438
|
}
|
439
|
}
|
440
|
else if (code == ss->escape_code)
|
441
|
{
|
442
|
ss->escape_code++;
|
443
|
ss->escaped = TRUE;
|
444
|
}
|
445
|
else
|
446
|
{
|
447
|
ss->output_buf[ss->output_octet_count++] = (uint8_t) code;
|
448
|
if (ss->output_octet_count >= ss->max_len - s->v42bis_parm_n7)
|
449
|
{
|
450
|
ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
|
451
|
ss->output_octet_count = 0;
|
452
|
}
|
453
|
}
|
454
|
}
|
455
|
else
|
456
|
{
|
457
|
if (new_code < V42BIS_N6)
|
458
|
{
|
459
|
/* We have a control code. */
|
460
|
switch (new_code)
|
461
|
{
|
462
|
case V42BIS_ETM:
|
463
|
printf("Hit V42BIS_ETM\n");
|
464
|
ss->transparent = TRUE;
|
465
|
code_len = 8;
|
466
|
break;
|
467
|
case V42BIS_FLUSH:
|
468
|
printf("Hit V42BIS_FLUSH\n");
|
469
|
v42bis_decompress_flush(s);
|
470
|
break;
|
471
|
case V42BIS_STEPUP:
|
472
|
/* We need to increase the codeword size */
|
473
|
printf("Hit V42BIS_STEPUP\n");
|
474
|
if (ss->v42bis_parm_c3 >= s->v42bis_parm_n2)
|
475
|
{
|
476
|
/* Invalid condition */
|
477
|
return -1;
|
478
|
}
|
479
|
code_len = ++ss->v42bis_parm_c2;
|
480
|
ss->v42bis_parm_c3 <<= 1;
|
481
|
break;
|
482
|
}
|
483
|
continue;
|
484
|
}
|
485
|
if (ss->first)
|
486
|
{
|
487
|
ss->first = FALSE;
|
488
|
ss->octet = new_code - V42BIS_N6;
|
489
|
ss->output_buf[0] = (uint8_t) ss->octet;
|
490
|
ss->output_octet_count = 1;
|
491
|
if (ss->output_octet_count >= ss->max_len - s->v42bis_parm_n7)
|
492
|
{
|
493
|
ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
|
494
|
ss->output_octet_count = 0;
|
495
|
}
|
496
|
ss->old_code = new_code;
|
497
|
continue;
|
498
|
}
|
499
|
/* Start at the end of the buffer, and decode backwards */
|
500
|
string = &decode_buf[V42BIS_MAX_STRING_SIZE - 1];
|
501
|
/* Check the received code is valid. It can't be too big, as we pulled only the expected number
|
502
|
of bits from the input stream. It could, however, be unknown. */
|
503
|
if (ss->dict[new_code].parent_code == 0xFFFF)
|
504
|
return -1;
|
505
|
/* Otherwise we do a straight decode of the new code. */
|
506
|
code = new_code;
|
507
|
/* Trace back through the octets which form the string, and output them. */
|
508
|
while (code >= V42BIS_N5)
|
509
|
{
|
510
|
if (code > 4095) {printf("Code is 0x%" PRIu32 "\n", code); exit(2);}
|
511
|
*string-- = ss->dict[code].node_octet;
|
512
|
code = ss->dict[code].parent_code;
|
513
|
}
|
514
|
*string = (uint8_t) (code - V42BIS_N6);
|
515
|
ss->octet = code - V42BIS_N6;
|
516
|
/* Output the decoded string. */
|
517
|
this_length = V42BIS_MAX_STRING_SIZE - (int) (string - decode_buf);
|
518
|
memcpy(ss->output_buf + ss->output_octet_count, string, this_length);
|
519
|
ss->output_octet_count += this_length;
|
520
|
if (ss->output_octet_count >= ss->max_len - s->v42bis_parm_n7)
|
521
|
{
|
522
|
ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
|
523
|
ss->output_octet_count = 0;
|
524
|
}
|
525
|
/* 6.4 Add the string to the dictionary */
|
526
|
if (ss->last_length < s->v42bis_parm_n7)
|
527
|
{
|
528
|
/* 6.4(a) The string does not exceed N7 in length */
|
529
|
if (ss->last_old_code != ss->old_code
|
530
|
||
|
531
|
ss->last_extra_octet != *string)
|
532
|
{
|
533
|
/* 6.4(b) The string is not in the table. */
|
534
|
ss->dict[ss->old_code].leaves++;
|
535
|
/* The new one is definitely a leaf */
|
536
|
ss->dict[ss->v42bis_parm_c1].parent_code = (uint16_t) ss->old_code;
|
537
|
ss->dict[ss->v42bis_parm_c1].leaves = 0;
|
538
|
ss->dict[ss->v42bis_parm_c1].node_octet = (uint8_t) ss->octet;
|
539
|
/* 6.5 Recovering a dictionary entry to use next */
|
540
|
for (;;)
|
541
|
{
|
542
|
/* 6.5(a) and (b) */
|
543
|
if (++ss->v42bis_parm_c1 >= s->v42bis_parm_n2)
|
544
|
ss->v42bis_parm_c1 = V42BIS_N5;
|
545
|
/* 6.5(c) We need to reuse a leaf node */
|
546
|
if (ss->dict[ss->v42bis_parm_c1].leaves)
|
547
|
continue;
|
548
|
/* 6.5(d) This is a leaf node, so re-use it */
|
549
|
/* Possibly make the parent a leaf node again */
|
550
|
if (ss->dict[ss->v42bis_parm_c1].parent_code != 0xFFFF)
|
551
|
ss->dict[ss->dict[ss->v42bis_parm_c1].parent_code].leaves--;
|
552
|
ss->dict[ss->v42bis_parm_c1].parent_code = 0xFFFF;
|
553
|
break;
|
554
|
}
|
555
|
}
|
556
|
}
|
557
|
/* Record the addition to the dictionary, so we can check for repeat attempts
|
558
|
at the next code - see II.4.3 */
|
559
|
ss->last_old_code = ss->old_code;
|
560
|
ss->last_extra_octet = *string;
|
561
|
|
562
|
ss->old_code = new_code;
|
563
|
ss->last_length = this_length;
|
564
|
}
|
565
|
}
|
566
|
return 0;
|
567
|
}
|
568
|
/*- End of function --------------------------------------------------------*/
|
569
|
|
570
|
int v42bis_decompress_flush(v42bis_state_t *s)
|
571
|
{
|
572
|
v42bis_decompress_state_t *ss;
|
573
|
|
574
|
ss = &s->decompress;
|
575
|
/* Push out anything remaining. */
|
576
|
if (ss->output_octet_count > 0)
|
577
|
{
|
578
|
ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
|
579
|
ss->output_octet_count = 0;
|
580
|
}
|
581
|
return 0;
|
582
|
}
|
583
|
/*- End of function --------------------------------------------------------*/
|
584
|
|
585
|
#if 0
|
586
|
int v42bis_decompress_dump(v42bis_state_t *s)
|
587
|
{
|
588
|
int i;
|
589
|
|
590
|
for (i = 0; i < V42BIS_MAX_CODEWORDS; i++)
|
591
|
{
|
592
|
if (s->decompress.dict[i].parent_code != 0xFFFF)
|
593
|
{
|
594
|
printf("Entry %4x, prior %4x, leaves %d, octet %2x\n", i, s->decompress.dict[i].parent_code, s->decompress.dict[i].leaves, s->decompress.dict[i].node_octet);
|
595
|
}
|
596
|
}
|
597
|
return 0;
|
598
|
}
|
599
|
/*- End of function --------------------------------------------------------*/
|
600
|
#endif
|
601
|
|
602
|
void v42bis_compression_control(v42bis_state_t *s, int mode)
|
603
|
{
|
604
|
s->compress.compression_mode = mode;
|
605
|
switch (mode)
|
606
|
{
|
607
|
case V42BIS_COMPRESSION_MODE_ALWAYS:
|
608
|
s->compress.change_transparency = -1;
|
609
|
break;
|
610
|
case V42BIS_COMPRESSION_MODE_NEVER:
|
611
|
s->compress.change_transparency = 1;
|
612
|
break;
|
613
|
}
|
614
|
}
|
615
|
/*- End of function --------------------------------------------------------*/
|
616
|
|
617
|
v42bis_state_t *v42bis_init(v42bis_state_t *s,
|
618
|
int negotiated_p0,
|
619
|
int negotiated_p1,
|
620
|
int negotiated_p2,
|
621
|
v42bis_frame_handler_t frame_handler,
|
622
|
void *frame_user_data,
|
623
|
int max_frame_len,
|
624
|
v42bis_data_handler_t data_handler,
|
625
|
void *data_user_data,
|
626
|
int max_data_len)
|
627
|
{
|
628
|
int i;
|
629
|
|
630
|
if (negotiated_p1 < 512 || negotiated_p1 > 65535)
|
631
|
return NULL;
|
632
|
if (negotiated_p2 < 6 || negotiated_p2 > V42BIS_MAX_STRING_SIZE)
|
633
|
return NULL;
|
634
|
if (s == NULL)
|
635
|
{
|
636
|
if ((s = (v42bis_state_t *) malloc(sizeof(*s))) == NULL)
|
637
|
return NULL;
|
638
|
}
|
639
|
memset(s, 0, sizeof(*s));
|
640
|
|
641
|
s->compress.handler = frame_handler;
|
642
|
s->compress.user_data = frame_user_data;
|
643
|
s->compress.max_len = (max_frame_len < 1024) ? max_frame_len : 1024;
|
644
|
|
645
|
s->decompress.handler = data_handler;
|
646
|
s->decompress.user_data = data_user_data;
|
647
|
s->decompress.max_len = (max_data_len < 1024) ? max_data_len : 1024;
|
648
|
|
649
|
s->v42bis_parm_p0 = negotiated_p0; /* default is both ways off */
|
650
|
|
651
|
s->v42bis_parm_n1 = top_bit(negotiated_p1 - 1) + 1;
|
652
|
s->v42bis_parm_n2 = negotiated_p1;
|
653
|
s->v42bis_parm_n7 = negotiated_p2;
|
654
|
|
655
|
/* 6.5 */
|
656
|
s->compress.v42bis_parm_c1 =
|
657
|
s->decompress.v42bis_parm_c1 = V42BIS_N5;
|
658
|
|
659
|
s->compress.v42bis_parm_c2 =
|
660
|
s->decompress.v42bis_parm_c2 = V42BIS_N3 + 1;
|
661
|
|
662
|
s->compress.v42bis_parm_c3 =
|
663
|
s->decompress.v42bis_parm_c3 = 2*V42BIS_N4;
|
664
|
|
665
|
s->compress.first =
|
666
|
s->decompress.first = TRUE;
|
667
|
for (i = 0; i < V42BIS_MAX_CODEWORDS; i++)
|
668
|
{
|
669
|
s->compress.dict[i].parent_code =
|
670
|
s->decompress.dict[i].parent_code = 0xFFFF;
|
671
|
s->compress.dict[i].leaves =
|
672
|
s->decompress.dict[i].leaves = 0;
|
673
|
}
|
674
|
/* Point the root nodes for decompression to themselves. It doesn't matter much what
|
675
|
they are set to, as long as they are considered "known" codes. */
|
676
|
for (i = 0; i < V42BIS_N5; i++)
|
677
|
s->decompress.dict[i].parent_code = (uint16_t) i;
|
678
|
s->compress.string_code = 0xFFFFFFFF;
|
679
|
s->compress.latest_code = 0xFFFFFFFF;
|
680
|
|
681
|
s->decompress.last_old_code = 0xFFFFFFFF;
|
682
|
s->decompress.last_extra_octet = -1;
|
683
|
|
684
|
s->compress.compression_mode = V42BIS_COMPRESSION_MODE_DYNAMIC;
|
685
|
|
686
|
return s;
|
687
|
}
|
688
|
/*- End of function --------------------------------------------------------*/
|
689
|
|
690
|
int v42bis_release(v42bis_state_t *s)
|
691
|
{
|
692
|
return 0;
|
693
|
}
|
694
|
/*- End of function --------------------------------------------------------*/
|
695
|
|
696
|
int v42bis_free(v42bis_state_t *s)
|
697
|
{
|
698
|
free(s);
|
699
|
return 0;
|
700
|
}
|
701
|
/*- End of function --------------------------------------------------------*/
|
702
|
/*- End of file ------------------------------------------------------------*/
|