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5
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1 /*
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2 * SpanDSP - a series of DSP components for telephony
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3 *
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4 * v42bis.c
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5 *
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6 * Written by Steve Underwood <steveu@coppice.org>
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7 *
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8 * Copyright (C) 2005 Steve Underwood
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9 *
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10 * All rights reserved.
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11 *
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12 * This program is free software; you can redistribute it and/or modify
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13 * it under the terms of the GNU General Public License version 2, as
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14 * published by the Free Software Foundation.
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15 *
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16 * This program is distributed in the hope that it will be useful,
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17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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19 * GNU General Public License for more details.
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20 *
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21 * You should have received a copy of the GNU General Public License
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22 * along with this program; if not, write to the Free Software
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23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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24 *
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25 * $Id: v42bis.c,v 1.29 2006/12/01 18:00:48 steveu Exp $
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26 */
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27
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28 /* THIS IS A WORK IN PROGRESS. IT IS NOT FINISHED.
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29 Currently it performs the core compression and decompression functions OK.
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30 However, a number of the bells and whistles in V.42bis are incomplete. */
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31
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32 /*! \file */
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33
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34 #ifdef HAVE_CONFIG_H
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35 #include <config.h>
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36 #endif
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37
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38 #include <stdio.h>
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39 #include <stdlib.h>
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40 #include <inttypes.h>
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41 #include <string.h>
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42 #include <errno.h>
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43 #include <fcntl.h>
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44 #include <ctype.h>
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45 #include <assert.h>
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46
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47 #include "spandsp/telephony.h"
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48 #include "spandsp/logging.h"
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49 #include "spandsp/bit_operations.h"
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50 #include "spandsp/v42bis.h"
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51
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52 /* Fixed parameters from the spec. */
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53 #define V42BIS_N3 8 /* Character size (bits) */
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54 #define V42BIS_N4 256 /* Number of characters in the alphabet */
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55 #define V42BIS_N5 (V42BIS_N4 + V42BIS_N6) /* Index number of first dictionary entry used to store a string */
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56 #define V42BIS_N6 3 /* Number of control codewords */
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57
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58 /* Control code words in compressed mode */
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59 enum
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60 {
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61 V42BIS_ETM = 0, /* Enter transparent mode */
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62 V42BIS_FLUSH = 1, /* Flush data */
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63 V42BIS_STEPUP = 2 /* Step up codeword size */
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64 };
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65
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66 /* Command codes in transparent mode */
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67 enum
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68 {
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69 V42BIS_ECM = 0, /* Enter compression mode */
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70 V42BIS_EID = 1, /* Escape character in data */
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71 V42BIS_RESET = 2 /* Force reinitialisation */
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72 };
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73
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74 static __inline__ void push_compressed_raw_octet(v42bis_compress_state_t *ss, int octet)
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75 {
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76 ss->output_buf[ss->output_octet_count++] = (uint8_t) octet;
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77 if (ss->output_octet_count >= ss->max_len)
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78 {
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79 ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
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80 ss->output_octet_count = 0;
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81 }
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82 }
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83 /*- End of function --------------------------------------------------------*/
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84
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85 static __inline__ void push_compressed_code(v42bis_compress_state_t *ss, int code)
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86 {
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87 ss->output_bit_buffer |= code << (32 - ss->v42bis_parm_c2 - ss->output_bit_count);
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88 ss->output_bit_count += ss->v42bis_parm_c2;
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89 while (ss->output_bit_count >= 8)
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90 {
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91 push_compressed_raw_octet(ss, ss->output_bit_buffer >> 24);
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92 ss->output_bit_buffer <<= 8;
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93 ss->output_bit_count -= 8;
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94 }
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95 }
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96 /*- End of function --------------------------------------------------------*/
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97
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98 static __inline__ void push_compressed_octet(v42bis_compress_state_t *ss, int code)
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99 {
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100 ss->output_bit_buffer |= code << (32 - 8 - ss->output_bit_count);
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101 ss->output_bit_count += 8;
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102 while (ss->output_bit_count >= 8)
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103 {
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104 push_compressed_raw_octet(ss, ss->output_bit_buffer >> 24);
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105 ss->output_bit_buffer <<= 8;
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106 ss->output_bit_count -= 8;
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107 }
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108 }
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109 /*- End of function --------------------------------------------------------*/
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110
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111 int v42bis_compress(v42bis_state_t *s, const uint8_t *buf, int len)
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112 {
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113 int ptr;
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114 int i;
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115 uint32_t octet;
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116 uint32_t code;
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117 v42bis_compress_state_t *ss;
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118
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119 ss = &s->compress;
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120 if ((s->v42bis_parm_p0 & 2) == 0)
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121 {
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122 /* Compression is off - just push the incoming data out */
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123 for (i = 0; i < len - ss->max_len; i += ss->max_len)
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124 ss->handler(ss->user_data, buf + i, ss->max_len);
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125 if (i < len)
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126 ss->handler(ss->user_data, buf + i, len - i);
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127 return 0;
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128 }
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129 ptr = 0;
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130 if (ss->first && len > 0)
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131 {
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132 octet = buf[ptr++];
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133 ss->string_code = octet + V42BIS_N6;
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134 if (ss->transparent)
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135 push_compressed_octet(ss, octet);
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136 ss->first = FALSE;
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137 }
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138 while (ptr < len)
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139 {
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140 octet = buf[ptr++];
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141 if ((ss->dict[ss->string_code].children[octet >> 5] & (1 << (octet & 0x1F))))
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142 {
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143 /* The leaf exists. Now find it in the table. */
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144 /* TODO: This is a brute force scan for a match. We need something better. */
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145 for (code = 0; code < ss->v42bis_parm_c3; code++)
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146 {
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147 if (ss->dict[code].parent_code == ss->string_code && ss->dict[code].node_octet == octet)
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148 break;
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149 }
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150 }
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151 else
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152 {
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153 /* The leaf does not exist. */
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154 code = s->v42bis_parm_n2;
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155 }
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156 /* 6.3(b) If the string matches a dictionary entry, and the entry is not that entry
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157 created by the last invocation of the string matching procedure, then the
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158 next character shall be read and appended to the string and this step
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159 repeated. */
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160 if (code < ss->v42bis_parm_c3 && code != ss->latest_code)
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161 {
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162 /* The string was found */
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163 ss->string_code = code;
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164 ss->string_length++;
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165 }
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166 else
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167 {
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168 /* The string is not in the table. */
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169 if (!ss->transparent)
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170 {
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171 /* 7.4 Encoding - we now have the longest matchable string, and will need to output the code for it. */
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172 while (ss->v42bis_parm_c1 >= ss->v42bis_parm_c3 && ss->v42bis_parm_c3 <= s->v42bis_parm_n2)
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173 {
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174 /* We need to increase the codeword size */
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175 /* 7.4(a) */
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176 push_compressed_code(ss, V42BIS_STEPUP);
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177 /* 7.4(b) */
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178 ss->v42bis_parm_c2++;
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179 /* 7.4(c) */
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180 ss->v42bis_parm_c3 <<= 1;
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181 /* 7.4(d) this might need to be repeated, so we loop */
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182 }
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183 /* 7.5 Transfer - output the last state of the string */
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184 push_compressed_code(ss, ss->string_code);
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185 }
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186 /* 7.6 Dictionary updating */
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187 /* 6.4 Add the string to the dictionary */
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188 /* 6.4(b) The string is not in the table. */
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189 if (code != ss->latest_code && ss->string_length < s->v42bis_parm_n7)
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190 {
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191 ss->latest_code = ss->v42bis_parm_c1;
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192 /* 6.4(a) The length of the string is in range for adding to the dictionary */
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193 /* If the last code was a leaf, it no longer is */
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194 ss->dict[ss->string_code].leaves++;
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195 ss->dict[ss->string_code].children[octet >> 5] |= (1 << (octet & 0x1F));
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196 /* The new one is definitely a leaf */
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197 ss->dict[ss->v42bis_parm_c1].parent_code = (uint16_t) ss->string_code;
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198 ss->dict[ss->v42bis_parm_c1].leaves = 0;
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199 ss->dict[ss->v42bis_parm_c1].node_octet = (uint8_t) octet;
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200 /* 7.7 Node recovery */
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201 /* 6.5 Recovering a dictionary entry to use next */
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202 for (;;)
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203 {
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204 /* 6.5(a) and (b) */
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205 if ((int) (++ss->v42bis_parm_c1) >= s->v42bis_parm_n2)
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206 ss->v42bis_parm_c1 = V42BIS_N5;
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207 /* 6.5(c) We need to reuse a leaf node */
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208 if (ss->dict[ss->v42bis_parm_c1].leaves)
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209 continue;
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210 if (ss->dict[ss->v42bis_parm_c1].parent_code == 0xFFFF)
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211 break;
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212 /* 6.5(d) Detach the leaf node from its parent, and re-use it */
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213 /* Possibly make the parent a leaf node again */
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214 ss->dict[ss->dict[ss->v42bis_parm_c1].parent_code].leaves--;
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215 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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216 ss->dict[ss->v42bis_parm_c1].parent_code = 0xFFFF;
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217 break;
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218 }
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219 }
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220 else
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221 {
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222 ss->latest_code = 0xFFFFFFFF;
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223 }
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224 /* 7.8 Data compressibility test */
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225 /* Filter on the balance of what went into the compressor, and what came out */
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226 ss->compressibility_filter += ((((8*ss->string_length - ss->v42bis_parm_c2) << 20) - ss->compressibility_filter) >> 10);
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227 if (ss->compression_mode == V42BIS_COMPRESSION_MODE_DYNAMIC)
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228 {
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229 /* Work out if it is appropriate to change between transparent and
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230 compressed mode. */
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231 if (ss->transparent)
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232 {
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233 if (ss->compressibility_filter > 0)
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234 {
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235 if (++ss->compressibility_persistence > 1000)
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236 {
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237 /* Schedule a switch to compressed mode */
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238 ss->change_transparency = -1;
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239 ss->compressibility_persistence = 0;
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240 }
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241 }
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242 else
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243 {
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244 ss->compressibility_persistence = 0;
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245 }
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246 }
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247 else
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248 {
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249 if (ss->compressibility_filter < 0)
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250 {
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251 if (++ss->compressibility_persistence > 1000)
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252 {
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253 /* Schedule a switch to transparent mode */
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254 ss->change_transparency = 1;
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255 ss->compressibility_persistence = 0;
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256 }
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257 }
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258 else
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259 {
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260 ss->compressibility_persistence = 0;
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261 }
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262 }
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263 }
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264 if (ss->change_transparency)
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265 {
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266 if (ss->change_transparency < 0)
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267 {
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268 if (ss->transparent)
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269 {
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270 printf("Going compressed\n");
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271 /* 7.8.1 Transition to compressed mode */
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272 /* Switch out of transparent now, between codes. We need to send the octet which did not
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273 match, just before switching. */
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274 if (octet == ss->escape_code)
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275 {
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276 push_compressed_octet(ss, ss->escape_code++);
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277 push_compressed_octet(ss, V42BIS_EID);
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278 }
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279 else
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280 {
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281 push_compressed_octet(ss, octet);
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282 }
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283 push_compressed_octet(ss, ss->escape_code++);
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284 push_compressed_octet(ss, V42BIS_ECM);
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285 ss->transparent = FALSE;
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286 }
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287 }
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288 else
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289 {
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290 if (!ss->transparent)
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291 {
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292 printf("Going transparent\n");
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293 /* 7.8.2 Transition to transparent mode */
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294 /* Switch into transparent now, between codes, and the unmatched octet should
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295 go out in transparent mode, just below */
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296 push_compressed_code(ss, V42BIS_ETM);
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297 ss->transparent = TRUE;
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298 }
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299 }
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300 ss->change_transparency = 0;
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301 }
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302 /* 7.8.3 Reset function - TODO */
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303 ss->string_code = octet + V42BIS_N6;
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304 ss->string_length = 1;
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305 }
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306 if (ss->transparent)
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307 {
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308 if (octet == ss->escape_code)
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309 {
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310 push_compressed_octet(ss, ss->escape_code++);
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311 push_compressed_octet(ss, V42BIS_EID);
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312 }
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313 else
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314 {
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315 push_compressed_octet(ss, octet);
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316 }
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317 }
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318 }
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319 return 0;
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320 }
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321 /*- End of function --------------------------------------------------------*/
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322
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323 int v42bis_compress_flush(v42bis_state_t *s)
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324 {
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325 v42bis_compress_state_t *ss;
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326
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327 ss = &s->compress;
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328 if (!ss->transparent)
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329 {
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330 /* Output the last state of the string */
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331 push_compressed_code(ss, ss->string_code);
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332 /* TODO: We use a positive FLUSH at all times. It is really needed, if the
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333 previous step resulted in no leftover bits. */
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334 push_compressed_code(ss, V42BIS_FLUSH);
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335 }
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336 while (ss->output_bit_count > 0)
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337 {
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338 push_compressed_raw_octet(ss, ss->output_bit_buffer >> 24);
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339 ss->output_bit_buffer <<= 8;
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340 ss->output_bit_count -= 8;
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341 }
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342 /* Now push out anything remaining. */
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343 if (ss->output_octet_count > 0)
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344 {
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345 ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
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346 ss->output_octet_count = 0;
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347 }
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348 return 0;
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349 }
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350 /*- End of function --------------------------------------------------------*/
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351
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352 #if 0
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353 int v42bis_compress_dump(v42bis_state_t *s)
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354 {
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355 int i;
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356
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357 for (i = 0; i < V42BIS_MAX_CODEWORDS; i++)
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358 {
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359 if (s->compress.dict[i].parent_code != 0xFFFF)
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360 {
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361 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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362 }
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363 }
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364 return 0;
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365 }
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366 /*- End of function --------------------------------------------------------*/
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367 #endif
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368
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369 int v42bis_decompress(v42bis_state_t *s, const uint8_t *buf, int len)
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370 {
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371 int ptr;
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372 int i;
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373 int this_length;
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374 uint8_t *string;
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375 uint32_t code;
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376 uint32_t new_code;
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377 int code_len;
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378 v42bis_decompress_state_t *ss;
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379 uint8_t decode_buf[V42BIS_MAX_STRING_SIZE];
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380
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381 ss = &s->decompress;
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382 if ((s->v42bis_parm_p0 & 1) == 0)
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383 {
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384 /* Compression is off - just push the incoming data out */
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385 for (i = 0; i < len - ss->max_len; i += ss->max_len)
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386 ss->handler(ss->user_data, buf + i, ss->max_len);
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387 if (i < len)
|
|
|
388 ss->handler(ss->user_data, buf + i, len - i);
|
|
|
389 return 0;
|
|
|
390 }
|
|
|
391 ptr = 0;
|
|
|
392 code_len = (ss->transparent) ? 8 : ss->v42bis_parm_c2;
|
|
|
393 for (;;)
|
|
|
394 {
|
|
|
395 /* Fill up the bit buffer. */
|
|
|
396 while (ss->input_bit_count < 32 - 8 && ptr < len)
|
|
|
397 {
|
|
|
398 ss->input_bit_count += 8;
|
|
|
399 ss->input_bit_buffer |= (uint32_t) buf[ptr++] << (32 - ss->input_bit_count);
|
|
|
400 }
|
|
|
401 if (ss->input_bit_count < code_len)
|
|
|
402 break;
|
|
|
403 new_code = ss->input_bit_buffer >> (32 - code_len);
|
|
|
404 ss->input_bit_count -= code_len;
|
|
|
405 ss->input_bit_buffer <<= code_len;
|
|
|
406 if (ss->transparent)
|
|
|
407 {
|
|
|
408 code = new_code;
|
|
|
409 if (ss->escaped)
|
|
|
410 {
|
|
|
411 ss->escaped = FALSE;
|
|
|
412 if (code == V42BIS_ECM)
|
|
|
413 {
|
|
|
414 printf("Hit V42BIS_ECM\n");
|
|
|
415 ss->transparent = FALSE;
|
|
|
416 code_len = ss->v42bis_parm_c2;
|
|
|
417 }
|
|
|
418 else if (code == V42BIS_EID)
|
|
|
419 {
|
|
|
420 printf("Hit V42BIS_EID\n");
|
|
|
421 ss->output_buf[ss->output_octet_count++] = ss->escape_code - 1;
|
|
|
422 if (ss->output_octet_count >= ss->max_len - s->v42bis_parm_n7)
|
|
|
423 {
|
|
|
424 ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
|
|
|
425 ss->output_octet_count = 0;
|
|
|
426 }
|
|
|
427 }
|
|
|
428 else if (code == V42BIS_RESET)
|
|
|
429 {
|
|
|
430 printf("Hit V42BIS_RESET\n");
|
|
|
431 }
|
|
|
432 else
|
|
|
433 {
|
|
|
434 printf("Hit V42BIS_???? - %" PRIu32 "\n", code);
|
|
|
435 }
|
|
|
436 }
|
|
|
437 else if (code == ss->escape_code)
|
|
|
438 {
|
|
|
439 ss->escape_code++;
|
|
|
440 ss->escaped = TRUE;
|
|
|
441 }
|
|
|
442 else
|
|
|
443 {
|
|
|
444 ss->output_buf[ss->output_octet_count++] = (uint8_t) code;
|
|
|
445 if (ss->output_octet_count >= ss->max_len - s->v42bis_parm_n7)
|
|
|
446 {
|
|
|
447 ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
|
|
|
448 ss->output_octet_count = 0;
|
|
|
449 }
|
|
|
450 }
|
|
|
451 }
|
|
|
452 else
|
|
|
453 {
|
|
|
454 if (new_code < V42BIS_N6)
|
|
|
455 {
|
|
|
456 /* We have a control code. */
|
|
|
457 switch (new_code)
|
|
|
458 {
|
|
|
459 case V42BIS_ETM:
|
|
|
460 printf("Hit V42BIS_ETM\n");
|
|
|
461 ss->transparent = TRUE;
|
|
|
462 code_len = 8;
|
|
|
463 break;
|
|
|
464 case V42BIS_FLUSH:
|
|
|
465 printf("Hit V42BIS_FLUSH\n");
|
|
|
466 v42bis_decompress_flush(s);
|
|
|
467 break;
|
|
|
468 case V42BIS_STEPUP:
|
|
|
469 /* We need to increase the codeword size */
|
|
|
470 printf("Hit V42BIS_STEPUP\n");
|
|
|
471 if (ss->v42bis_parm_c3 >= s->v42bis_parm_n2)
|
|
|
472 {
|
|
|
473 /* Invalid condition */
|
|
|
474 return -1;
|
|
|
475 }
|
|
|
476 code_len = ++ss->v42bis_parm_c2;
|
|
|
477 ss->v42bis_parm_c3 <<= 1;
|
|
|
478 break;
|
|
|
479 }
|
|
|
480 continue;
|
|
|
481 }
|
|
|
482 if (ss->first)
|
|
|
483 {
|
|
|
484 ss->first = FALSE;
|
|
|
485 ss->octet = new_code - V42BIS_N6;
|
|
|
486 ss->output_buf[0] = (uint8_t) ss->octet;
|
|
|
487 ss->output_octet_count = 1;
|
|
|
488 if (ss->output_octet_count >= ss->max_len - s->v42bis_parm_n7)
|
|
|
489 {
|
|
|
490 ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
|
|
|
491 ss->output_octet_count = 0;
|
|
|
492 }
|
|
|
493 ss->old_code = new_code;
|
|
|
494 continue;
|
|
|
495 }
|
|
|
496 /* Start at the end of the buffer, and decode backwards */
|
|
|
497 string = &decode_buf[V42BIS_MAX_STRING_SIZE - 1];
|
|
|
498 /* Check the received code is valid. It can't be too big, as we pulled only the expected number
|
|
|
499 of bits from the input stream. It could, however, be unknown. */
|
|
|
500 if (ss->dict[new_code].parent_code == 0xFFFF)
|
|
|
501 return -1;
|
|
|
502 /* Otherwise we do a straight decode of the new code. */
|
|
|
503 code = new_code;
|
|
|
504 /* Trace back through the octets which form the string, and output them. */
|
|
|
505 while (code >= V42BIS_N5)
|
|
|
506 {
|
|
|
507 if (code > 4095) {printf("Code is 0x%" PRIu32 "\n", code); exit(2);}
|
|
|
508 *string-- = ss->dict[code].node_octet;
|
|
|
509 code = ss->dict[code].parent_code;
|
|
|
510 }
|
|
|
511 *string = (uint8_t) (code - V42BIS_N6);
|
|
|
512 ss->octet = code - V42BIS_N6;
|
|
|
513 /* Output the decoded string. */
|
|
|
514 this_length = V42BIS_MAX_STRING_SIZE - (int) (string - decode_buf);
|
|
|
515 memcpy(ss->output_buf + ss->output_octet_count, string, this_length);
|
|
|
516 ss->output_octet_count += this_length;
|
|
|
517 if (ss->output_octet_count >= ss->max_len - s->v42bis_parm_n7)
|
|
|
518 {
|
|
|
519 ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
|
|
|
520 ss->output_octet_count = 0;
|
|
|
521 }
|
|
|
522 /* 6.4 Add the string to the dictionary */
|
|
|
523 if (ss->last_length < s->v42bis_parm_n7)
|
|
|
524 {
|
|
|
525 /* 6.4(a) The string does not exceed N7 in length */
|
|
|
526 if (ss->last_old_code != ss->old_code
|
|
|
527 ||
|
|
|
528 ss->last_extra_octet != *string)
|
|
|
529 {
|
|
|
530 /* 6.4(b) The string is not in the table. */
|
|
|
531 ss->dict[ss->old_code].leaves++;
|
|
|
532 /* The new one is definitely a leaf */
|
|
|
533 ss->dict[ss->v42bis_parm_c1].parent_code = (uint16_t) ss->old_code;
|
|
|
534 ss->dict[ss->v42bis_parm_c1].leaves = 0;
|
|
|
535 ss->dict[ss->v42bis_parm_c1].node_octet = (uint8_t) ss->octet;
|
|
|
536 /* 6.5 Recovering a dictionary entry to use next */
|
|
|
537 for (;;)
|
|
|
538 {
|
|
|
539 /* 6.5(a) and (b) */
|
|
|
540 if (++ss->v42bis_parm_c1 >= s->v42bis_parm_n2)
|
|
|
541 ss->v42bis_parm_c1 = V42BIS_N5;
|
|
|
542 /* 6.5(c) We need to reuse a leaf node */
|
|
|
543 if (ss->dict[ss->v42bis_parm_c1].leaves)
|
|
|
544 continue;
|
|
|
545 /* 6.5(d) This is a leaf node, so re-use it */
|
|
|
546 /* Possibly make the parent a leaf node again */
|
|
|
547 if (ss->dict[ss->v42bis_parm_c1].parent_code != 0xFFFF)
|
|
|
548 ss->dict[ss->dict[ss->v42bis_parm_c1].parent_code].leaves--;
|
|
|
549 ss->dict[ss->v42bis_parm_c1].parent_code = 0xFFFF;
|
|
|
550 break;
|
|
|
551 }
|
|
|
552 }
|
|
|
553 }
|
|
|
554 /* Record the addition to the dictionary, so we can check for repeat attempts
|
|
|
555 at the next code - see II.4.3 */
|
|
|
556 ss->last_old_code = ss->old_code;
|
|
|
557 ss->last_extra_octet = *string;
|
|
|
558
|
|
|
559 ss->old_code = new_code;
|
|
|
560 ss->last_length = this_length;
|
|
|
561 }
|
|
|
562 }
|
|
|
563 return 0;
|
|
|
564 }
|
|
|
565 /*- End of function --------------------------------------------------------*/
|
|
|
566
|
|
|
567 int v42bis_decompress_flush(v42bis_state_t *s)
|
|
|
568 {
|
|
|
569 v42bis_decompress_state_t *ss;
|
|
|
570
|
|
|
571 ss = &s->decompress;
|
|
|
572 /* Push out anything remaining. */
|
|
|
573 if (ss->output_octet_count > 0)
|
|
|
574 {
|
|
|
575 ss->handler(ss->user_data, ss->output_buf, ss->output_octet_count);
|
|
|
576 ss->output_octet_count = 0;
|
|
|
577 }
|
|
|
578 return 0;
|
|
|
579 }
|
|
|
580 /*- End of function --------------------------------------------------------*/
|
|
|
581
|
|
|
582 #if 0
|
|
|
583 int v42bis_decompress_dump(v42bis_state_t *s)
|
|
|
584 {
|
|
|
585 int i;
|
|
|
586
|
|
|
587 for (i = 0; i < V42BIS_MAX_CODEWORDS; i++)
|
|
|
588 {
|
|
|
589 if (s->decompress.dict[i].parent_code != 0xFFFF)
|
|
|
590 {
|
|
|
591 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);
|
|
|
592 }
|
|
|
593 }
|
|
|
594 return 0;
|
|
|
595 }
|
|
|
596 /*- End of function --------------------------------------------------------*/
|
|
|
597 #endif
|
|
|
598
|
|
|
599 void v42bis_compression_control(v42bis_state_t *s, int mode)
|
|
|
600 {
|
|
|
601 s->compress.compression_mode = mode;
|
|
|
602 switch (mode)
|
|
|
603 {
|
|
|
604 case V42BIS_COMPRESSION_MODE_ALWAYS:
|
|
|
605 s->compress.change_transparency = -1;
|
|
|
606 break;
|
|
|
607 case V42BIS_COMPRESSION_MODE_NEVER:
|
|
|
608 s->compress.change_transparency = 1;
|
|
|
609 break;
|
|
|
610 }
|
|
|
611 }
|
|
|
612 /*- End of function --------------------------------------------------------*/
|
|
|
613
|
|
|
614 v42bis_state_t *v42bis_init(v42bis_state_t *s,
|
|
|
615 int negotiated_p0,
|
|
|
616 int negotiated_p1,
|
|
|
617 int negotiated_p2,
|
|
|
618 v42bis_frame_handler_t frame_handler,
|
|
|
619 void *frame_user_data,
|
|
|
620 int max_frame_len,
|
|
|
621 v42bis_data_handler_t data_handler,
|
|
|
622 void *data_user_data,
|
|
|
623 int max_data_len)
|
|
|
624 {
|
|
|
625 int i;
|
|
|
626
|
|
|
627 if (negotiated_p1 < 512 || negotiated_p1 > 65535)
|
|
|
628 return NULL;
|
|
|
629 if (negotiated_p2 < 6 || negotiated_p2 > V42BIS_MAX_STRING_SIZE)
|
|
|
630 return NULL;
|
|
|
631 if (s == NULL)
|
|
|
632 {
|
|
|
633 if ((s = (v42bis_state_t *) malloc(sizeof(*s))) == NULL)
|
|
|
634 return NULL;
|
|
|
635 }
|
|
|
636 memset(s, 0, sizeof(*s));
|
|
|
637
|
|
|
638 s->compress.handler = frame_handler;
|
|
|
639 s->compress.user_data = frame_user_data;
|
|
|
640 s->compress.max_len = (max_frame_len < 1024) ? max_frame_len : 1024;
|
|
|
641
|
|
|
642 s->decompress.handler = data_handler;
|
|
|
643 s->decompress.user_data = data_user_data;
|
|
|
644 s->decompress.max_len = (max_data_len < 1024) ? max_data_len : 1024;
|
|
|
645
|
|
|
646 s->v42bis_parm_p0 = negotiated_p0; /* default is both ways off */
|
|
|
647
|
|
|
648 s->v42bis_parm_n1 = top_bit(negotiated_p1 - 1) + 1;
|
|
|
649 s->v42bis_parm_n2 = negotiated_p1;
|
|
|
650 s->v42bis_parm_n7 = negotiated_p2;
|
|
|
651
|
|
|
652 /* 6.5 */
|
|
|
653 s->compress.v42bis_parm_c1 =
|
|
|
654 s->decompress.v42bis_parm_c1 = V42BIS_N5;
|
|
|
655
|
|
|
656 s->compress.v42bis_parm_c2 =
|
|
|
657 s->decompress.v42bis_parm_c2 = V42BIS_N3 + 1;
|
|
|
658
|
|
|
659 s->compress.v42bis_parm_c3 =
|
|
|
660 s->decompress.v42bis_parm_c3 = 2*V42BIS_N4;
|
|
|
661
|
|
|
662 s->compress.first =
|
|
|
663 s->decompress.first = TRUE;
|
|
|
664 for (i = 0; i < V42BIS_MAX_CODEWORDS; i++)
|
|
|
665 {
|
|
|
666 s->compress.dict[i].parent_code =
|
|
|
667 s->decompress.dict[i].parent_code = 0xFFFF;
|
|
|
668 s->compress.dict[i].leaves =
|
|
|
669 s->decompress.dict[i].leaves = 0;
|
|
|
670 }
|
|
|
671 /* Point the root nodes for decompression to themselves. It doesn't matter much what
|
|
|
672 they are set to, as long as they are considered "known" codes. */
|
|
|
673 for (i = 0; i < V42BIS_N5; i++)
|
|
|
674 s->decompress.dict[i].parent_code = (uint16_t) i;
|
|
|
675 s->compress.string_code = 0xFFFFFFFF;
|
|
|
676 s->compress.latest_code = 0xFFFFFFFF;
|
|
|
677
|
|
|
678 s->decompress.last_old_code = 0xFFFFFFFF;
|
|
|
679 s->decompress.last_extra_octet = -1;
|
|
|
680
|
|
|
681 s->compress.compression_mode = V42BIS_COMPRESSION_MODE_DYNAMIC;
|
|
|
682
|
|
|
683 return s;
|
|
|
684 }
|
|
|
685 /*- End of function --------------------------------------------------------*/
|
|
|
686
|
|
|
687 int v42bis_release(v42bis_state_t *s)
|
|
|
688 {
|
|
|
689 free(s);
|
|
|
690 return 0;
|
|
|
691 }
|
|
|
692 /*- End of function --------------------------------------------------------*/
|
|
|
693 /*- End of file ------------------------------------------------------------*/
|
