1 /***************************************************************************/ |
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2 /* */ |
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3 /* ftzopen.c */ |
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4 /* */ |
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5 /* FreeType support for .Z compressed files. */ |
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6 /* */ |
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7 /* This optional component relies on NetBSD's zopen(). It should mainly */ |
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8 /* be used to parse compressed PCF fonts, as found with many X11 server */ |
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9 /* distributions. */ |
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10 /* */ |
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11 /* Copyright 2005, 2006, 2007, 2009 by David Turner. */ |
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12 /* */ |
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13 /* This file is part of the FreeType project, and may only be used, */ |
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14 /* modified, and distributed under the terms of the FreeType project */ |
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15 /* license, LICENSE.TXT. By continuing to use, modify, or distribute */ |
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16 /* this file you indicate that you have read the license and */ |
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17 /* understand and accept it fully. */ |
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18 /* */ |
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19 /***************************************************************************/ |
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20 |
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21 #include "ftzopen.h" |
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22 #include FT_INTERNAL_MEMORY_H |
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23 #include FT_INTERNAL_STREAM_H |
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24 #include FT_INTERNAL_DEBUG_H |
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25 |
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26 |
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27 static int |
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28 ft_lzwstate_refill( FT_LzwState state ) |
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29 { |
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30 FT_ULong count; |
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31 |
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32 |
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33 if ( state->in_eof ) |
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34 return -1; |
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35 |
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36 count = FT_Stream_TryRead( state->source, |
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37 state->buf_tab, |
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38 state->num_bits ); /* WHY? */ |
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39 |
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40 state->buf_size = (FT_UInt)count; |
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41 state->buf_total += count; |
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42 state->in_eof = FT_BOOL( count < state->num_bits ); |
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43 state->buf_offset = 0; |
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44 state->buf_size = ( state->buf_size << 3 ) - ( state->num_bits - 1 ); |
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45 |
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46 if ( count == 0 ) /* end of file */ |
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47 return -1; |
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48 |
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49 return 0; |
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50 } |
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51 |
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52 |
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53 static FT_Int32 |
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54 ft_lzwstate_get_code( FT_LzwState state ) |
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55 { |
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56 FT_UInt num_bits = state->num_bits; |
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57 FT_Int offset = state->buf_offset; |
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58 FT_Byte* p; |
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59 FT_Int result; |
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60 |
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61 |
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62 if ( state->buf_clear || |
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63 offset >= state->buf_size || |
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64 state->free_ent >= state->free_bits ) |
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65 { |
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66 if ( state->free_ent >= state->free_bits ) |
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67 { |
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68 state->num_bits = ++num_bits; |
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69 state->free_bits = state->num_bits < state->max_bits |
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70 ? (FT_UInt)( ( 1UL << num_bits ) - 256 ) |
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71 : state->max_free + 1; |
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72 } |
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73 |
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74 if ( state->buf_clear ) |
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75 { |
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76 state->num_bits = num_bits = LZW_INIT_BITS; |
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77 state->free_bits = (FT_UInt)( ( 1UL << num_bits ) - 256 ); |
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78 state->buf_clear = 0; |
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79 } |
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80 |
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81 if ( ft_lzwstate_refill( state ) < 0 ) |
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82 return -1; |
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83 |
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84 offset = 0; |
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85 } |
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86 |
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87 state->buf_offset = offset + num_bits; |
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88 |
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89 p = &state->buf_tab[offset >> 3]; |
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90 offset &= 7; |
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91 result = *p++ >> offset; |
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92 offset = 8 - offset; |
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93 num_bits -= offset; |
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94 |
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95 if ( num_bits >= 8 ) |
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96 { |
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97 result |= *p++ << offset; |
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98 offset += 8; |
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99 num_bits -= 8; |
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100 } |
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101 if ( num_bits > 0 ) |
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102 result |= ( *p & LZW_MASK( num_bits ) ) << offset; |
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103 |
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104 return result; |
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105 } |
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106 |
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107 |
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108 /* grow the character stack */ |
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109 static int |
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110 ft_lzwstate_stack_grow( FT_LzwState state ) |
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111 { |
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112 if ( state->stack_top >= state->stack_size ) |
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113 { |
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114 FT_Memory memory = state->memory; |
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115 FT_Error error; |
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116 FT_Offset old_size = state->stack_size; |
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117 FT_Offset new_size = old_size; |
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118 |
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119 new_size = new_size + ( new_size >> 1 ) + 4; |
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120 |
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121 if ( state->stack == state->stack_0 ) |
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122 { |
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123 state->stack = NULL; |
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124 old_size = 0; |
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125 } |
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126 |
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127 if ( FT_RENEW_ARRAY( state->stack, old_size, new_size ) ) |
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128 return -1; |
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129 |
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130 state->stack_size = new_size; |
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131 } |
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132 return 0; |
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133 } |
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134 |
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135 |
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136 /* grow the prefix/suffix arrays */ |
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137 static int |
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138 ft_lzwstate_prefix_grow( FT_LzwState state ) |
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139 { |
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140 FT_UInt old_size = state->prefix_size; |
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141 FT_UInt new_size = old_size; |
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142 FT_Memory memory = state->memory; |
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143 FT_Error error; |
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144 |
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145 |
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146 if ( new_size == 0 ) /* first allocation -> 9 bits */ |
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147 new_size = 512; |
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148 else |
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149 new_size += new_size >> 2; /* don't grow too fast */ |
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150 |
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151 /* |
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152 * Note that the `suffix' array is located in the same memory block |
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153 * pointed to by `prefix'. |
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154 * |
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155 * I know that sizeof(FT_Byte) == 1 by definition, but it is clearer |
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156 * to write it literally. |
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157 * |
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158 */ |
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159 if ( FT_REALLOC_MULT( state->prefix, old_size, new_size, |
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160 sizeof ( FT_UShort ) + sizeof ( FT_Byte ) ) ) |
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161 return -1; |
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162 |
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163 /* now adjust `suffix' and move the data accordingly */ |
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164 state->suffix = (FT_Byte*)( state->prefix + new_size ); |
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165 |
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166 FT_MEM_MOVE( state->suffix, |
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167 state->prefix + old_size, |
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168 old_size * sizeof ( FT_Byte ) ); |
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169 |
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170 state->prefix_size = new_size; |
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171 return 0; |
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172 } |
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173 |
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174 |
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175 FT_LOCAL_DEF( void ) |
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176 ft_lzwstate_reset( FT_LzwState state ) |
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177 { |
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178 state->in_eof = 0; |
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179 state->buf_offset = 0; |
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180 state->buf_size = 0; |
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181 state->buf_clear = 0; |
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182 state->buf_total = 0; |
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183 state->stack_top = 0; |
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184 state->num_bits = LZW_INIT_BITS; |
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185 state->phase = FT_LZW_PHASE_START; |
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186 } |
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187 |
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188 |
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189 FT_LOCAL_DEF( void ) |
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190 ft_lzwstate_init( FT_LzwState state, |
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191 FT_Stream source ) |
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192 { |
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193 FT_ZERO( state ); |
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194 |
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195 state->source = source; |
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196 state->memory = source->memory; |
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197 |
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198 state->prefix = NULL; |
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199 state->suffix = NULL; |
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200 state->prefix_size = 0; |
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201 |
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202 state->stack = state->stack_0; |
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203 state->stack_size = sizeof ( state->stack_0 ); |
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204 |
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205 ft_lzwstate_reset( state ); |
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206 } |
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207 |
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208 |
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209 FT_LOCAL_DEF( void ) |
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210 ft_lzwstate_done( FT_LzwState state ) |
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211 { |
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212 FT_Memory memory = state->memory; |
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213 |
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214 |
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215 ft_lzwstate_reset( state ); |
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216 |
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217 if ( state->stack != state->stack_0 ) |
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218 FT_FREE( state->stack ); |
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219 |
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220 FT_FREE( state->prefix ); |
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221 state->suffix = NULL; |
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222 |
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223 FT_ZERO( state ); |
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224 } |
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225 |
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226 |
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227 #define FTLZW_STACK_PUSH( c ) \ |
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228 FT_BEGIN_STMNT \ |
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229 if ( state->stack_top >= state->stack_size && \ |
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230 ft_lzwstate_stack_grow( state ) < 0 ) \ |
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231 goto Eof; \ |
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232 \ |
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233 state->stack[state->stack_top++] = (FT_Byte)(c); \ |
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234 FT_END_STMNT |
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235 |
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236 |
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237 FT_LOCAL_DEF( FT_ULong ) |
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238 ft_lzwstate_io( FT_LzwState state, |
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239 FT_Byte* buffer, |
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240 FT_ULong out_size ) |
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241 { |
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242 FT_ULong result = 0; |
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243 |
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244 FT_UInt old_char = state->old_char; |
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245 FT_UInt old_code = state->old_code; |
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246 FT_UInt in_code = state->in_code; |
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247 |
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248 |
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249 if ( out_size == 0 ) |
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250 goto Exit; |
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251 |
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252 switch ( state->phase ) |
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253 { |
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254 case FT_LZW_PHASE_START: |
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255 { |
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256 FT_Byte max_bits; |
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257 FT_Int32 c; |
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258 |
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259 |
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260 /* skip magic bytes, and read max_bits + block_flag */ |
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261 if ( FT_Stream_Seek( state->source, 2 ) != 0 || |
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262 FT_Stream_TryRead( state->source, &max_bits, 1 ) != 1 ) |
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263 goto Eof; |
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264 |
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265 state->max_bits = max_bits & LZW_BIT_MASK; |
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266 state->block_mode = max_bits & LZW_BLOCK_MASK; |
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267 state->max_free = (FT_UInt)( ( 1UL << state->max_bits ) - 256 ); |
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268 |
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269 if ( state->max_bits > LZW_MAX_BITS ) |
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270 goto Eof; |
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271 |
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272 state->num_bits = LZW_INIT_BITS; |
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273 state->free_ent = ( state->block_mode ? LZW_FIRST |
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274 : LZW_CLEAR ) - 256; |
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275 in_code = 0; |
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276 |
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277 state->free_bits = state->num_bits < state->max_bits |
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278 ? (FT_UInt)( ( 1UL << state->num_bits ) - 256 ) |
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279 : state->max_free + 1; |
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280 |
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281 c = ft_lzwstate_get_code( state ); |
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282 if ( c < 0 ) |
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283 goto Eof; |
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284 |
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285 old_code = old_char = (FT_UInt)c; |
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286 |
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287 if ( buffer ) |
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288 buffer[result] = (FT_Byte)old_char; |
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289 |
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290 if ( ++result >= out_size ) |
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291 goto Exit; |
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292 |
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293 state->phase = FT_LZW_PHASE_CODE; |
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294 } |
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295 /* fall-through */ |
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296 |
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297 case FT_LZW_PHASE_CODE: |
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298 { |
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299 FT_Int32 c; |
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300 FT_UInt code; |
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301 |
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302 |
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303 NextCode: |
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304 c = ft_lzwstate_get_code( state ); |
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305 if ( c < 0 ) |
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306 goto Eof; |
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307 |
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308 code = (FT_UInt)c; |
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309 |
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310 if ( code == LZW_CLEAR && state->block_mode ) |
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311 { |
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312 /* why not LZW_FIRST-256 ? */ |
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313 state->free_ent = ( LZW_FIRST - 1 ) - 256; |
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314 state->buf_clear = 1; |
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315 c = ft_lzwstate_get_code( state ); |
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316 if ( c < 0 ) |
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317 goto Eof; |
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318 |
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319 code = (FT_UInt)c; |
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320 } |
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321 |
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322 in_code = code; /* save code for later */ |
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323 |
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324 if ( code >= 256U ) |
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325 { |
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326 /* special case for KwKwKwK */ |
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327 if ( code - 256U >= state->free_ent ) |
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328 { |
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329 FTLZW_STACK_PUSH( old_char ); |
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330 code = old_code; |
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331 } |
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332 |
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333 while ( code >= 256U ) |
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334 { |
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335 if ( !state->prefix ) |
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336 goto Eof; |
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337 |
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338 FTLZW_STACK_PUSH( state->suffix[code - 256] ); |
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339 code = state->prefix[code - 256]; |
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340 } |
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341 } |
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342 |
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343 old_char = code; |
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344 FTLZW_STACK_PUSH( old_char ); |
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345 |
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346 state->phase = FT_LZW_PHASE_STACK; |
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347 } |
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348 /* fall-through */ |
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349 |
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350 case FT_LZW_PHASE_STACK: |
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351 { |
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352 while ( state->stack_top > 0 ) |
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353 { |
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354 --state->stack_top; |
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355 |
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356 if ( buffer ) |
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357 buffer[result] = state->stack[state->stack_top]; |
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358 |
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359 if ( ++result == out_size ) |
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360 goto Exit; |
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361 } |
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362 |
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363 /* now create new entry */ |
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364 if ( state->free_ent < state->max_free ) |
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365 { |
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366 if ( state->free_ent >= state->prefix_size && |
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367 ft_lzwstate_prefix_grow( state ) < 0 ) |
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368 goto Eof; |
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369 |
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370 FT_ASSERT( state->free_ent < state->prefix_size ); |
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371 |
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372 state->prefix[state->free_ent] = (FT_UShort)old_code; |
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373 state->suffix[state->free_ent] = (FT_Byte) old_char; |
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374 |
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375 state->free_ent += 1; |
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376 } |
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377 |
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378 old_code = in_code; |
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379 |
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380 state->phase = FT_LZW_PHASE_CODE; |
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381 goto NextCode; |
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382 } |
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383 |
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384 default: /* state == EOF */ |
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385 ; |
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386 } |
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387 |
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388 Exit: |
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389 state->old_code = old_code; |
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390 state->old_char = old_char; |
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391 state->in_code = in_code; |
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392 |
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393 return result; |
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394 |
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395 Eof: |
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396 state->phase = FT_LZW_PHASE_EOF; |
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397 goto Exit; |
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398 } |
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399 |
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400 |
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401 /* END */ |
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