1 | /* |
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2 | * jchuff.c |
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3 | * |
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4 | * Copyright (C) 1991-1997, Thomas G. Lane. |
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5 | * Modified 2006-2009 by Guido Vollbeding. |
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6 | * This file is part of the Independent JPEG Group's software. |
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7 | * For conditions of distribution and use, see the accompanying README file. |
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8 | * |
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9 | * This file contains Huffman entropy encoding routines. |
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10 | * Both sequential and progressive modes are supported in this single module. |
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11 | * |
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12 | * Much of the complexity here has to do with supporting output suspension. |
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13 | * If the data destination module demands suspension, we want to be able to |
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14 | * back up to the start of the current MCU. To do this, we copy state |
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15 | * variables into local working storage, and update them back to the |
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16 | * permanent JPEG objects only upon successful completion of an MCU. |
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17 | * |
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18 | * We do not support output suspension for the progressive JPEG mode, since |
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19 | * the library currently does not allow multiple-scan files to be written |
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20 | * with output suspension. |
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21 | */ |
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22 | |
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23 | #define JPEG_INTERNALS |
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24 | #include "jinclude.h" |
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25 | #include "jpeglib.h" |
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26 | |
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27 | |
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28 | /* The legal range of a DCT coefficient is |
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29 | * -1024 .. +1023 for 8-bit data; |
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30 | * -16384 .. +16383 for 12-bit data. |
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31 | * Hence the magnitude should always fit in 10 or 14 bits respectively. |
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32 | */ |
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33 | |
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34 | #if BITS_IN_JSAMPLE == 8 |
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35 | #define MAX_COEF_BITS 10 |
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36 | #else |
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37 | #define MAX_COEF_BITS 14 |
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38 | #endif |
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39 | |
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40 | /* Derived data constructed for each Huffman table */ |
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41 | |
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42 | typedef struct { |
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43 | unsigned int ehufco[256]; /* code for each symbol */ |
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44 | char ehufsi[256]; /* length of code for each symbol */ |
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45 | /* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */ |
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46 | } c_derived_tbl; |
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47 | |
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48 | |
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49 | /* Expanded entropy encoder object for Huffman encoding. |
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50 | * |
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51 | * The savable_state subrecord contains fields that change within an MCU, |
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52 | * but must not be updated permanently until we complete the MCU. |
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53 | */ |
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54 | |
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55 | typedef struct { |
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56 | INT32 put_buffer; /* current bit-accumulation buffer */ |
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57 | int put_bits; /* # of bits now in it */ |
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58 | int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ |
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59 | } savable_state; |
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60 | |
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61 | /* This macro is to work around compilers with missing or broken |
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62 | * structure assignment. You'll need to fix this code if you have |
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63 | * such a compiler and you change MAX_COMPS_IN_SCAN. |
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64 | */ |
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65 | |
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66 | #ifndef NO_STRUCT_ASSIGN |
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67 | #define ASSIGN_STATE(dest,src) ((dest) = (src)) |
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68 | #else |
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69 | #if MAX_COMPS_IN_SCAN == 4 |
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70 | #define ASSIGN_STATE(dest,src) \ |
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71 | ((dest).put_buffer = (src).put_buffer, \ |
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72 | (dest).put_bits = (src).put_bits, \ |
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73 | (dest).last_dc_val[0] = (src).last_dc_val[0], \ |
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74 | (dest).last_dc_val[1] = (src).last_dc_val[1], \ |
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75 | (dest).last_dc_val[2] = (src).last_dc_val[2], \ |
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76 | (dest).last_dc_val[3] = (src).last_dc_val[3]) |
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77 | #endif |
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78 | #endif |
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79 | |
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80 | |
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81 | typedef struct { |
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82 | struct jpeg_entropy_encoder pub; /* public fields */ |
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83 | |
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84 | savable_state saved; /* Bit buffer & DC state at start of MCU */ |
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85 | |
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86 | /* These fields are NOT loaded into local working state. */ |
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87 | unsigned int restarts_to_go; /* MCUs left in this restart interval */ |
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88 | int next_restart_num; /* next restart number to write (0-7) */ |
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89 | |
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90 | /* Following four fields used only in sequential mode */ |
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91 | |
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92 | /* Pointers to derived tables (these workspaces have image lifespan) */ |
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93 | c_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS]; |
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94 | c_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS]; |
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95 | |
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96 | /* Statistics tables for optimization */ |
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97 | long * dc_count_ptrs[NUM_HUFF_TBLS]; |
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98 | long * ac_count_ptrs[NUM_HUFF_TBLS]; |
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99 | |
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100 | /* Following fields used only in progressive mode */ |
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101 | |
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102 | /* Mode flag: TRUE for optimization, FALSE for actual data output */ |
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103 | boolean gather_statistics; |
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104 | |
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105 | /* next_output_byte/free_in_buffer are local copies of cinfo->dest fields. |
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106 | */ |
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107 | JOCTET * next_output_byte; /* => next byte to write in buffer */ |
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108 | size_t free_in_buffer; /* # of byte spaces remaining in buffer */ |
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109 | j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */ |
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110 | |
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111 | /* Coding status for AC components */ |
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112 | int ac_tbl_no; /* the table number of the single component */ |
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113 | unsigned int EOBRUN; /* run length of EOBs */ |
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114 | unsigned int BE; /* # of buffered correction bits before MCU */ |
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115 | char * bit_buffer; /* buffer for correction bits (1 per char) */ |
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116 | /* packing correction bits tightly would save some space but cost time... */ |
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117 | |
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118 | /* Pointers to derived tables (these workspaces have image lifespan). |
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119 | * Since any one scan in progressive mode codes only DC or only AC, |
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120 | * we only need one set of tables, not one for DC and one for AC. |
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121 | */ |
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122 | c_derived_tbl * derived_tbls[NUM_HUFF_TBLS]; |
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123 | |
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124 | /* Statistics tables for optimization; again, one set is enough */ |
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125 | long * count_ptrs[NUM_HUFF_TBLS]; |
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126 | } huff_entropy_encoder; |
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127 | |
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128 | typedef huff_entropy_encoder * huff_entropy_ptr; |
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129 | |
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130 | /* Working state while writing an MCU (sequential mode). |
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131 | * This struct contains all the fields that are needed by subroutines. |
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132 | */ |
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133 | |
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134 | typedef struct { |
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135 | JOCTET * next_output_byte; /* => next byte to write in buffer */ |
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136 | size_t free_in_buffer; /* # of byte spaces remaining in buffer */ |
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137 | savable_state cur; /* Current bit buffer & DC state */ |
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138 | j_compress_ptr cinfo; /* dump_buffer needs access to this */ |
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139 | } working_state; |
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140 | |
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141 | /* MAX_CORR_BITS is the number of bits the AC refinement correction-bit |
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142 | * buffer can hold. Larger sizes may slightly improve compression, but |
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143 | * 1000 is already well into the realm of overkill. |
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144 | * The minimum safe size is 64 bits. |
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145 | */ |
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146 | |
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147 | #define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */ |
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148 | |
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149 | /* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32. |
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150 | * We assume that int right shift is unsigned if INT32 right shift is, |
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151 | * which should be safe. |
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152 | */ |
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153 | |
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154 | #ifdef RIGHT_SHIFT_IS_UNSIGNED |
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155 | #define ISHIFT_TEMPS int ishift_temp; |
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156 | #define IRIGHT_SHIFT(x,shft) \ |
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157 | ((ishift_temp = (x)) < 0 ? \ |
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158 | (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \ |
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159 | (ishift_temp >> (shft))) |
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160 | #else |
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161 | #define ISHIFT_TEMPS |
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162 | #define IRIGHT_SHIFT(x,shft) ((x) >> (shft)) |
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163 | #endif |
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164 | |
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165 | |
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166 | /* |
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167 | * Compute the derived values for a Huffman table. |
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168 | * This routine also performs some validation checks on the table. |
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169 | */ |
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170 | |
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171 | LOCAL(void) |
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172 | jpeg_make_c_derived_tbl (j_compress_ptr cinfo, boolean isDC, int tblno, |
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173 | c_derived_tbl ** pdtbl) |
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174 | { |
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175 | JHUFF_TBL *htbl; |
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176 | c_derived_tbl *dtbl; |
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177 | int p, i, l, lastp, si, maxsymbol; |
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178 | char huffsize[257]; |
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179 | unsigned int huffcode[257]; |
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180 | unsigned int code; |
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181 | |
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182 | /* Note that huffsize[] and huffcode[] are filled in code-length order, |
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183 | * paralleling the order of the symbols themselves in htbl->huffval[]. |
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184 | */ |
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185 | |
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186 | /* Find the input Huffman table */ |
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187 | if (tblno < 0 || tblno >= NUM_HUFF_TBLS) |
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188 | ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno); |
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189 | htbl = |
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190 | isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno]; |
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191 | if (htbl == NULL) |
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192 | ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno); |
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193 | |
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194 | /* Allocate a workspace if we haven't already done so. */ |
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195 | if (*pdtbl == NULL) |
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196 | *pdtbl = (c_derived_tbl *) |
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197 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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198 | SIZEOF(c_derived_tbl)); |
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199 | dtbl = *pdtbl; |
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200 | |
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201 | /* Figure C.1: make table of Huffman code length for each symbol */ |
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202 | |
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203 | p = 0; |
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204 | for (l = 1; l <= 16; l++) { |
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205 | i = (int) htbl->bits[l]; |
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206 | if (i < 0 || p + i > 256) /* protect against table overrun */ |
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207 | ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); |
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208 | while (i--) |
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209 | huffsize[p++] = (char) l; |
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210 | } |
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211 | huffsize[p] = 0; |
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212 | lastp = p; |
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213 | |
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214 | /* Figure C.2: generate the codes themselves */ |
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215 | /* We also validate that the counts represent a legal Huffman code tree. */ |
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216 | |
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217 | code = 0; |
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218 | si = huffsize[0]; |
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219 | p = 0; |
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220 | while (huffsize[p]) { |
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221 | while (((int) huffsize[p]) == si) { |
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222 | huffcode[p++] = code; |
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223 | code++; |
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224 | } |
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225 | /* code is now 1 more than the last code used for codelength si; but |
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226 | * it must still fit in si bits, since no code is allowed to be all ones. |
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227 | */ |
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228 | if (((INT32) code) >= (((INT32) 1) << si)) |
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229 | ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); |
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230 | code <<= 1; |
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231 | si++; |
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232 | } |
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233 | |
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234 | /* Figure C.3: generate encoding tables */ |
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235 | /* These are code and size indexed by symbol value */ |
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236 | |
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237 | /* Set all codeless symbols to have code length 0; |
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238 | * this lets us detect duplicate VAL entries here, and later |
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239 | * allows emit_bits to detect any attempt to emit such symbols. |
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240 | */ |
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241 | MEMZERO(dtbl->ehufsi, SIZEOF(dtbl->ehufsi)); |
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242 | |
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243 | /* This is also a convenient place to check for out-of-range |
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244 | * and duplicated VAL entries. We allow 0..255 for AC symbols |
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245 | * but only 0..15 for DC. (We could constrain them further |
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246 | * based on data depth and mode, but this seems enough.) |
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247 | */ |
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248 | maxsymbol = isDC ? 15 : 255; |
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249 | |
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250 | for (p = 0; p < lastp; p++) { |
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251 | i = htbl->huffval[p]; |
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252 | if (i < 0 || i > maxsymbol || dtbl->ehufsi[i]) |
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253 | ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); |
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254 | dtbl->ehufco[i] = huffcode[p]; |
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255 | dtbl->ehufsi[i] = huffsize[p]; |
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256 | } |
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257 | } |
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258 | |
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259 | |
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260 | /* Outputting bytes to the file. |
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261 | * NB: these must be called only when actually outputting, |
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262 | * that is, entropy->gather_statistics == FALSE. |
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263 | */ |
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264 | |
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265 | /* Emit a byte, taking 'action' if must suspend. */ |
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266 | #define emit_byte_s(state,val,action) \ |
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267 | { *(state)->next_output_byte++ = (JOCTET) (val); \ |
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268 | if (--(state)->free_in_buffer == 0) \ |
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269 | if (! dump_buffer_s(state)) \ |
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270 | { action; } } |
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271 | |
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272 | /* Emit a byte */ |
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273 | #define emit_byte_e(entropy,val) \ |
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274 | { *(entropy)->next_output_byte++ = (JOCTET) (val); \ |
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275 | if (--(entropy)->free_in_buffer == 0) \ |
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276 | dump_buffer_e(entropy); } |
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277 | |
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278 | |
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279 | LOCAL(boolean) |
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280 | dump_buffer_s (working_state * state) |
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281 | /* Empty the output buffer; return TRUE if successful, FALSE if must suspend */ |
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282 | { |
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283 | struct jpeg_destination_mgr * dest = state->cinfo->dest; |
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284 | |
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285 | if (! (*dest->empty_output_buffer) (state->cinfo)) |
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286 | return FALSE; |
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287 | /* After a successful buffer dump, must reset buffer pointers */ |
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288 | state->next_output_byte = dest->next_output_byte; |
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289 | state->free_in_buffer = dest->free_in_buffer; |
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290 | return TRUE; |
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291 | } |
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292 | |
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293 | |
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294 | LOCAL(void) |
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295 | dump_buffer_e (huff_entropy_ptr entropy) |
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296 | /* Empty the output buffer; we do not support suspension in this case. */ |
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297 | { |
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298 | struct jpeg_destination_mgr * dest = entropy->cinfo->dest; |
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299 | |
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300 | if (! (*dest->empty_output_buffer) (entropy->cinfo)) |
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301 | ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND); |
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302 | /* After a successful buffer dump, must reset buffer pointers */ |
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303 | entropy->next_output_byte = dest->next_output_byte; |
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304 | entropy->free_in_buffer = dest->free_in_buffer; |
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305 | } |
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306 | |
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307 | |
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308 | /* Outputting bits to the file */ |
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309 | |
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310 | /* Only the right 24 bits of put_buffer are used; the valid bits are |
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311 | * left-justified in this part. At most 16 bits can be passed to emit_bits |
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312 | * in one call, and we never retain more than 7 bits in put_buffer |
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313 | * between calls, so 24 bits are sufficient. |
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314 | */ |
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315 | |
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316 | INLINE |
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317 | LOCAL(boolean) |
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318 | emit_bits_s (working_state * state, unsigned int code, int size) |
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319 | /* Emit some bits; return TRUE if successful, FALSE if must suspend */ |
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320 | { |
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321 | /* This routine is heavily used, so it's worth coding tightly. */ |
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322 | register INT32 put_buffer = (INT32) code; |
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323 | register int put_bits = state->cur.put_bits; |
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324 | |
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325 | /* if size is 0, caller used an invalid Huffman table entry */ |
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326 | if (size == 0) |
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327 | ERREXIT(state->cinfo, JERR_HUFF_MISSING_CODE); |
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328 | |
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329 | put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */ |
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330 | |
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331 | put_bits += size; /* new number of bits in buffer */ |
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332 | |
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333 | put_buffer <<= 24 - put_bits; /* align incoming bits */ |
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334 | |
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335 | put_buffer |= state->cur.put_buffer; /* and merge with old buffer contents */ |
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336 | |
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337 | while (put_bits >= 8) { |
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338 | int c = (int) ((put_buffer >> 16) & 0xFF); |
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339 | |
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340 | emit_byte_s(state, c, return FALSE); |
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341 | if (c == 0xFF) { /* need to stuff a zero byte? */ |
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342 | emit_byte_s(state, 0, return FALSE); |
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343 | } |
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344 | put_buffer <<= 8; |
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345 | put_bits -= 8; |
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346 | } |
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347 | |
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348 | state->cur.put_buffer = put_buffer; /* update state variables */ |
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349 | state->cur.put_bits = put_bits; |
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350 | |
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351 | return TRUE; |
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352 | } |
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353 | |
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354 | |
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355 | INLINE |
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356 | LOCAL(void) |
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357 | emit_bits_e (huff_entropy_ptr entropy, unsigned int code, int size) |
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358 | /* Emit some bits, unless we are in gather mode */ |
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359 | { |
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360 | /* This routine is heavily used, so it's worth coding tightly. */ |
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361 | register INT32 put_buffer = (INT32) code; |
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362 | register int put_bits = entropy->saved.put_bits; |
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363 | |
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364 | /* if size is 0, caller used an invalid Huffman table entry */ |
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365 | if (size == 0) |
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366 | ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); |
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367 | |
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368 | if (entropy->gather_statistics) |
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369 | return; /* do nothing if we're only getting stats */ |
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370 | |
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371 | put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */ |
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372 | |
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373 | put_bits += size; /* new number of bits in buffer */ |
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374 | |
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375 | put_buffer <<= 24 - put_bits; /* align incoming bits */ |
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376 | |
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377 | /* and merge with old buffer contents */ |
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378 | put_buffer |= entropy->saved.put_buffer; |
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379 | |
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380 | while (put_bits >= 8) { |
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381 | int c = (int) ((put_buffer >> 16) & 0xFF); |
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382 | |
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383 | emit_byte_e(entropy, c); |
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384 | if (c == 0xFF) { /* need to stuff a zero byte? */ |
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385 | emit_byte_e(entropy, 0); |
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386 | } |
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387 | put_buffer <<= 8; |
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388 | put_bits -= 8; |
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389 | } |
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390 | |
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391 | entropy->saved.put_buffer = put_buffer; /* update variables */ |
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392 | entropy->saved.put_bits = put_bits; |
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393 | } |
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394 | |
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395 | |
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396 | LOCAL(boolean) |
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397 | flush_bits_s (working_state * state) |
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398 | { |
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399 | if (! emit_bits_s(state, 0x7F, 7)) /* fill any partial byte with ones */ |
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400 | return FALSE; |
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401 | state->cur.put_buffer = 0; /* and reset bit-buffer to empty */ |
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402 | state->cur.put_bits = 0; |
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403 | return TRUE; |
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404 | } |
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405 | |
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406 | |
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407 | LOCAL(void) |
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408 | flush_bits_e (huff_entropy_ptr entropy) |
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409 | { |
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410 | emit_bits_e(entropy, 0x7F, 7); /* fill any partial byte with ones */ |
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411 | entropy->saved.put_buffer = 0; /* and reset bit-buffer to empty */ |
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412 | entropy->saved.put_bits = 0; |
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413 | } |
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414 | |
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415 | |
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416 | /* |
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417 | * Emit (or just count) a Huffman symbol. |
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418 | */ |
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419 | |
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420 | INLINE |
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421 | LOCAL(void) |
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422 | emit_symbol (huff_entropy_ptr entropy, int tbl_no, int symbol) |
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423 | { |
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424 | if (entropy->gather_statistics) |
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425 | entropy->count_ptrs[tbl_no][symbol]++; |
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426 | else { |
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427 | c_derived_tbl * tbl = entropy->derived_tbls[tbl_no]; |
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428 | emit_bits_e(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]); |
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429 | } |
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430 | } |
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431 | |
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432 | |
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433 | /* |
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434 | * Emit bits from a correction bit buffer. |
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435 | */ |
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436 | |
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437 | LOCAL(void) |
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438 | emit_buffered_bits (huff_entropy_ptr entropy, char * bufstart, |
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439 | unsigned int nbits) |
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440 | { |
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441 | if (entropy->gather_statistics) |
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442 | return; /* no real work */ |
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443 | |
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444 | while (nbits > 0) { |
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445 | emit_bits_e(entropy, (unsigned int) (*bufstart), 1); |
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446 | bufstart++; |
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447 | nbits--; |
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448 | } |
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449 | } |
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450 | |
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451 | |
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452 | /* |
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453 | * Emit any pending EOBRUN symbol. |
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454 | */ |
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455 | |
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456 | LOCAL(void) |
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457 | emit_eobrun (huff_entropy_ptr entropy) |
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458 | { |
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459 | register int temp, nbits; |
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460 | |
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461 | if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */ |
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462 | temp = entropy->EOBRUN; |
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463 | nbits = 0; |
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464 | while ((temp >>= 1)) |
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465 | nbits++; |
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466 | /* safety check: shouldn't happen given limited correction-bit buffer */ |
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467 | if (nbits > 14) |
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468 | ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); |
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469 | |
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470 | emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4); |
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471 | if (nbits) |
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472 | emit_bits_e(entropy, entropy->EOBRUN, nbits); |
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473 | |
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474 | entropy->EOBRUN = 0; |
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475 | |
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476 | /* Emit any buffered correction bits */ |
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477 | emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE); |
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478 | entropy->BE = 0; |
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479 | } |
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480 | } |
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481 | |
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482 | |
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483 | /* |
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484 | * Emit a restart marker & resynchronize predictions. |
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485 | */ |
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486 | |
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487 | LOCAL(boolean) |
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488 | emit_restart_s (working_state * state, int restart_num) |
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489 | { |
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490 | int ci; |
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491 | |
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492 | if (! flush_bits_s(state)) |
---|
493 | return FALSE; |
---|
494 | |
---|
495 | emit_byte_s(state, 0xFF, return FALSE); |
---|
496 | emit_byte_s(state, JPEG_RST0 + restart_num, return FALSE); |
---|
497 | |
---|
498 | /* Re-initialize DC predictions to 0 */ |
---|
499 | for (ci = 0; ci < state->cinfo->comps_in_scan; ci++) |
---|
500 | state->cur.last_dc_val[ci] = 0; |
---|
501 | |
---|
502 | /* The restart counter is not updated until we successfully write the MCU. */ |
---|
503 | |
---|
504 | return TRUE; |
---|
505 | } |
---|
506 | |
---|
507 | |
---|
508 | LOCAL(void) |
---|
509 | emit_restart_e (huff_entropy_ptr entropy, int restart_num) |
---|
510 | { |
---|
511 | int ci; |
---|
512 | |
---|
513 | emit_eobrun(entropy); |
---|
514 | |
---|
515 | if (! entropy->gather_statistics) { |
---|
516 | flush_bits_e(entropy); |
---|
517 | emit_byte_e(entropy, 0xFF); |
---|
518 | emit_byte_e(entropy, JPEG_RST0 + restart_num); |
---|
519 | } |
---|
520 | |
---|
521 | if (entropy->cinfo->Ss == 0) { |
---|
522 | /* Re-initialize DC predictions to 0 */ |
---|
523 | for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++) |
---|
524 | entropy->saved.last_dc_val[ci] = 0; |
---|
525 | } else { |
---|
526 | /* Re-initialize all AC-related fields to 0 */ |
---|
527 | entropy->EOBRUN = 0; |
---|
528 | entropy->BE = 0; |
---|
529 | } |
---|
530 | } |
---|
531 | |
---|
532 | |
---|
533 | /* |
---|
534 | * MCU encoding for DC initial scan (either spectral selection, |
---|
535 | * or first pass of successive approximation). |
---|
536 | */ |
---|
537 | |
---|
538 | METHODDEF(boolean) |
---|
539 | encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
---|
540 | { |
---|
541 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
---|
542 | register int temp, temp2; |
---|
543 | register int nbits; |
---|
544 | int blkn, ci; |
---|
545 | int Al = cinfo->Al; |
---|
546 | JBLOCKROW block; |
---|
547 | jpeg_component_info * compptr; |
---|
548 | ISHIFT_TEMPS |
---|
549 | |
---|
550 | entropy->next_output_byte = cinfo->dest->next_output_byte; |
---|
551 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |
---|
552 | |
---|
553 | /* Emit restart marker if needed */ |
---|
554 | if (cinfo->restart_interval) |
---|
555 | if (entropy->restarts_to_go == 0) |
---|
556 | emit_restart_e(entropy, entropy->next_restart_num); |
---|
557 | |
---|
558 | /* Encode the MCU data blocks */ |
---|
559 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
---|
560 | block = MCU_data[blkn]; |
---|
561 | ci = cinfo->MCU_membership[blkn]; |
---|
562 | compptr = cinfo->cur_comp_info[ci]; |
---|
563 | |
---|
564 | /* Compute the DC value after the required point transform by Al. |
---|
565 | * This is simply an arithmetic right shift. |
---|
566 | */ |
---|
567 | temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al); |
---|
568 | |
---|
569 | /* DC differences are figured on the point-transformed values. */ |
---|
570 | temp = temp2 - entropy->saved.last_dc_val[ci]; |
---|
571 | entropy->saved.last_dc_val[ci] = temp2; |
---|
572 | |
---|
573 | /* Encode the DC coefficient difference per section G.1.2.1 */ |
---|
574 | temp2 = temp; |
---|
575 | if (temp < 0) { |
---|
576 | temp = -temp; /* temp is abs value of input */ |
---|
577 | /* For a negative input, want temp2 = bitwise complement of abs(input) */ |
---|
578 | /* This code assumes we are on a two's complement machine */ |
---|
579 | temp2--; |
---|
580 | } |
---|
581 | |
---|
582 | /* Find the number of bits needed for the magnitude of the coefficient */ |
---|
583 | nbits = 0; |
---|
584 | while (temp) { |
---|
585 | nbits++; |
---|
586 | temp >>= 1; |
---|
587 | } |
---|
588 | /* Check for out-of-range coefficient values. |
---|
589 | * Since we're encoding a difference, the range limit is twice as much. |
---|
590 | */ |
---|
591 | if (nbits > MAX_COEF_BITS+1) |
---|
592 | ERREXIT(cinfo, JERR_BAD_DCT_COEF); |
---|
593 | |
---|
594 | /* Count/emit the Huffman-coded symbol for the number of bits */ |
---|
595 | emit_symbol(entropy, compptr->dc_tbl_no, nbits); |
---|
596 | |
---|
597 | /* Emit that number of bits of the value, if positive, */ |
---|
598 | /* or the complement of its magnitude, if negative. */ |
---|
599 | if (nbits) /* emit_bits rejects calls with size 0 */ |
---|
600 | emit_bits_e(entropy, (unsigned int) temp2, nbits); |
---|
601 | } |
---|
602 | |
---|
603 | cinfo->dest->next_output_byte = entropy->next_output_byte; |
---|
604 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |
---|
605 | |
---|
606 | /* Update restart-interval state too */ |
---|
607 | if (cinfo->restart_interval) { |
---|
608 | if (entropy->restarts_to_go == 0) { |
---|
609 | entropy->restarts_to_go = cinfo->restart_interval; |
---|
610 | entropy->next_restart_num++; |
---|
611 | entropy->next_restart_num &= 7; |
---|
612 | } |
---|
613 | entropy->restarts_to_go--; |
---|
614 | } |
---|
615 | |
---|
616 | return TRUE; |
---|
617 | } |
---|
618 | |
---|
619 | |
---|
620 | /* |
---|
621 | * MCU encoding for AC initial scan (either spectral selection, |
---|
622 | * or first pass of successive approximation). |
---|
623 | */ |
---|
624 | |
---|
625 | METHODDEF(boolean) |
---|
626 | encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
---|
627 | { |
---|
628 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
---|
629 | register int temp, temp2; |
---|
630 | register int nbits; |
---|
631 | register int r, k; |
---|
632 | int Se = cinfo->Se; |
---|
633 | int Al = cinfo->Al; |
---|
634 | JBLOCKROW block; |
---|
635 | |
---|
636 | entropy->next_output_byte = cinfo->dest->next_output_byte; |
---|
637 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |
---|
638 | |
---|
639 | /* Emit restart marker if needed */ |
---|
640 | if (cinfo->restart_interval) |
---|
641 | if (entropy->restarts_to_go == 0) |
---|
642 | emit_restart_e(entropy, entropy->next_restart_num); |
---|
643 | |
---|
644 | /* Encode the MCU data block */ |
---|
645 | block = MCU_data[0]; |
---|
646 | |
---|
647 | /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */ |
---|
648 | |
---|
649 | r = 0; /* r = run length of zeros */ |
---|
650 | |
---|
651 | for (k = cinfo->Ss; k <= Se; k++) { |
---|
652 | if ((temp = (*block)[jpeg_natural_order[k]]) == 0) { |
---|
653 | r++; |
---|
654 | continue; |
---|
655 | } |
---|
656 | /* We must apply the point transform by Al. For AC coefficients this |
---|
657 | * is an integer division with rounding towards 0. To do this portably |
---|
658 | * in C, we shift after obtaining the absolute value; so the code is |
---|
659 | * interwoven with finding the abs value (temp) and output bits (temp2). |
---|
660 | */ |
---|
661 | if (temp < 0) { |
---|
662 | temp = -temp; /* temp is abs value of input */ |
---|
663 | temp >>= Al; /* apply the point transform */ |
---|
664 | /* For a negative coef, want temp2 = bitwise complement of abs(coef) */ |
---|
665 | temp2 = ~temp; |
---|
666 | } else { |
---|
667 | temp >>= Al; /* apply the point transform */ |
---|
668 | temp2 = temp; |
---|
669 | } |
---|
670 | /* Watch out for case that nonzero coef is zero after point transform */ |
---|
671 | if (temp == 0) { |
---|
672 | r++; |
---|
673 | continue; |
---|
674 | } |
---|
675 | |
---|
676 | /* Emit any pending EOBRUN */ |
---|
677 | if (entropy->EOBRUN > 0) |
---|
678 | emit_eobrun(entropy); |
---|
679 | /* if run length > 15, must emit special run-length-16 codes (0xF0) */ |
---|
680 | while (r > 15) { |
---|
681 | emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); |
---|
682 | r -= 16; |
---|
683 | } |
---|
684 | |
---|
685 | /* Find the number of bits needed for the magnitude of the coefficient */ |
---|
686 | nbits = 1; /* there must be at least one 1 bit */ |
---|
687 | while ((temp >>= 1)) |
---|
688 | nbits++; |
---|
689 | /* Check for out-of-range coefficient values */ |
---|
690 | if (nbits > MAX_COEF_BITS) |
---|
691 | ERREXIT(cinfo, JERR_BAD_DCT_COEF); |
---|
692 | |
---|
693 | /* Count/emit Huffman symbol for run length / number of bits */ |
---|
694 | emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits); |
---|
695 | |
---|
696 | /* Emit that number of bits of the value, if positive, */ |
---|
697 | /* or the complement of its magnitude, if negative. */ |
---|
698 | emit_bits_e(entropy, (unsigned int) temp2, nbits); |
---|
699 | |
---|
700 | r = 0; /* reset zero run length */ |
---|
701 | } |
---|
702 | |
---|
703 | if (r > 0) { /* If there are trailing zeroes, */ |
---|
704 | entropy->EOBRUN++; /* count an EOB */ |
---|
705 | if (entropy->EOBRUN == 0x7FFF) |
---|
706 | emit_eobrun(entropy); /* force it out to avoid overflow */ |
---|
707 | } |
---|
708 | |
---|
709 | cinfo->dest->next_output_byte = entropy->next_output_byte; |
---|
710 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |
---|
711 | |
---|
712 | /* Update restart-interval state too */ |
---|
713 | if (cinfo->restart_interval) { |
---|
714 | if (entropy->restarts_to_go == 0) { |
---|
715 | entropy->restarts_to_go = cinfo->restart_interval; |
---|
716 | entropy->next_restart_num++; |
---|
717 | entropy->next_restart_num &= 7; |
---|
718 | } |
---|
719 | entropy->restarts_to_go--; |
---|
720 | } |
---|
721 | |
---|
722 | return TRUE; |
---|
723 | } |
---|
724 | |
---|
725 | |
---|
726 | /* |
---|
727 | * MCU encoding for DC successive approximation refinement scan. |
---|
728 | * Note: we assume such scans can be multi-component, although the spec |
---|
729 | * is not very clear on the point. |
---|
730 | */ |
---|
731 | |
---|
732 | METHODDEF(boolean) |
---|
733 | encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
---|
734 | { |
---|
735 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
---|
736 | register int temp; |
---|
737 | int blkn; |
---|
738 | int Al = cinfo->Al; |
---|
739 | JBLOCKROW block; |
---|
740 | |
---|
741 | entropy->next_output_byte = cinfo->dest->next_output_byte; |
---|
742 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |
---|
743 | |
---|
744 | /* Emit restart marker if needed */ |
---|
745 | if (cinfo->restart_interval) |
---|
746 | if (entropy->restarts_to_go == 0) |
---|
747 | emit_restart_e(entropy, entropy->next_restart_num); |
---|
748 | |
---|
749 | /* Encode the MCU data blocks */ |
---|
750 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
---|
751 | block = MCU_data[blkn]; |
---|
752 | |
---|
753 | /* We simply emit the Al'th bit of the DC coefficient value. */ |
---|
754 | temp = (*block)[0]; |
---|
755 | emit_bits_e(entropy, (unsigned int) (temp >> Al), 1); |
---|
756 | } |
---|
757 | |
---|
758 | cinfo->dest->next_output_byte = entropy->next_output_byte; |
---|
759 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |
---|
760 | |
---|
761 | /* Update restart-interval state too */ |
---|
762 | if (cinfo->restart_interval) { |
---|
763 | if (entropy->restarts_to_go == 0) { |
---|
764 | entropy->restarts_to_go = cinfo->restart_interval; |
---|
765 | entropy->next_restart_num++; |
---|
766 | entropy->next_restart_num &= 7; |
---|
767 | } |
---|
768 | entropy->restarts_to_go--; |
---|
769 | } |
---|
770 | |
---|
771 | return TRUE; |
---|
772 | } |
---|
773 | |
---|
774 | |
---|
775 | /* |
---|
776 | * MCU encoding for AC successive approximation refinement scan. |
---|
777 | */ |
---|
778 | |
---|
779 | METHODDEF(boolean) |
---|
780 | encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
---|
781 | { |
---|
782 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
---|
783 | register int temp; |
---|
784 | register int r, k; |
---|
785 | int EOB; |
---|
786 | char *BR_buffer; |
---|
787 | unsigned int BR; |
---|
788 | int Se = cinfo->Se; |
---|
789 | int Al = cinfo->Al; |
---|
790 | JBLOCKROW block; |
---|
791 | int absvalues[DCTSIZE2]; |
---|
792 | |
---|
793 | entropy->next_output_byte = cinfo->dest->next_output_byte; |
---|
794 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |
---|
795 | |
---|
796 | /* Emit restart marker if needed */ |
---|
797 | if (cinfo->restart_interval) |
---|
798 | if (entropy->restarts_to_go == 0) |
---|
799 | emit_restart_e(entropy, entropy->next_restart_num); |
---|
800 | |
---|
801 | /* Encode the MCU data block */ |
---|
802 | block = MCU_data[0]; |
---|
803 | |
---|
804 | /* It is convenient to make a pre-pass to determine the transformed |
---|
805 | * coefficients' absolute values and the EOB position. |
---|
806 | */ |
---|
807 | EOB = 0; |
---|
808 | for (k = cinfo->Ss; k <= Se; k++) { |
---|
809 | temp = (*block)[jpeg_natural_order[k]]; |
---|
810 | /* We must apply the point transform by Al. For AC coefficients this |
---|
811 | * is an integer division with rounding towards 0. To do this portably |
---|
812 | * in C, we shift after obtaining the absolute value. |
---|
813 | */ |
---|
814 | if (temp < 0) |
---|
815 | temp = -temp; /* temp is abs value of input */ |
---|
816 | temp >>= Al; /* apply the point transform */ |
---|
817 | absvalues[k] = temp; /* save abs value for main pass */ |
---|
818 | if (temp == 1) |
---|
819 | EOB = k; /* EOB = index of last newly-nonzero coef */ |
---|
820 | } |
---|
821 | |
---|
822 | /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */ |
---|
823 | |
---|
824 | r = 0; /* r = run length of zeros */ |
---|
825 | BR = 0; /* BR = count of buffered bits added now */ |
---|
826 | BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */ |
---|
827 | |
---|
828 | for (k = cinfo->Ss; k <= Se; k++) { |
---|
829 | if ((temp = absvalues[k]) == 0) { |
---|
830 | r++; |
---|
831 | continue; |
---|
832 | } |
---|
833 | |
---|
834 | /* Emit any required ZRLs, but not if they can be folded into EOB */ |
---|
835 | while (r > 15 && k <= EOB) { |
---|
836 | /* emit any pending EOBRUN and the BE correction bits */ |
---|
837 | emit_eobrun(entropy); |
---|
838 | /* Emit ZRL */ |
---|
839 | emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); |
---|
840 | r -= 16; |
---|
841 | /* Emit buffered correction bits that must be associated with ZRL */ |
---|
842 | emit_buffered_bits(entropy, BR_buffer, BR); |
---|
843 | BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ |
---|
844 | BR = 0; |
---|
845 | } |
---|
846 | |
---|
847 | /* If the coef was previously nonzero, it only needs a correction bit. |
---|
848 | * NOTE: a straight translation of the spec's figure G.7 would suggest |
---|
849 | * that we also need to test r > 15. But if r > 15, we can only get here |
---|
850 | * if k > EOB, which implies that this coefficient is not 1. |
---|
851 | */ |
---|
852 | if (temp > 1) { |
---|
853 | /* The correction bit is the next bit of the absolute value. */ |
---|
854 | BR_buffer[BR++] = (char) (temp & 1); |
---|
855 | continue; |
---|
856 | } |
---|
857 | |
---|
858 | /* Emit any pending EOBRUN and the BE correction bits */ |
---|
859 | emit_eobrun(entropy); |
---|
860 | |
---|
861 | /* Count/emit Huffman symbol for run length / number of bits */ |
---|
862 | emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1); |
---|
863 | |
---|
864 | /* Emit output bit for newly-nonzero coef */ |
---|
865 | temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1; |
---|
866 | emit_bits_e(entropy, (unsigned int) temp, 1); |
---|
867 | |
---|
868 | /* Emit buffered correction bits that must be associated with this code */ |
---|
869 | emit_buffered_bits(entropy, BR_buffer, BR); |
---|
870 | BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ |
---|
871 | BR = 0; |
---|
872 | r = 0; /* reset zero run length */ |
---|
873 | } |
---|
874 | |
---|
875 | if (r > 0 || BR > 0) { /* If there are trailing zeroes, */ |
---|
876 | entropy->EOBRUN++; /* count an EOB */ |
---|
877 | entropy->BE += BR; /* concat my correction bits to older ones */ |
---|
878 | /* We force out the EOB if we risk either: |
---|
879 | * 1. overflow of the EOB counter; |
---|
880 | * 2. overflow of the correction bit buffer during the next MCU. |
---|
881 | */ |
---|
882 | if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1)) |
---|
883 | emit_eobrun(entropy); |
---|
884 | } |
---|
885 | |
---|
886 | cinfo->dest->next_output_byte = entropy->next_output_byte; |
---|
887 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |
---|
888 | |
---|
889 | /* Update restart-interval state too */ |
---|
890 | if (cinfo->restart_interval) { |
---|
891 | if (entropy->restarts_to_go == 0) { |
---|
892 | entropy->restarts_to_go = cinfo->restart_interval; |
---|
893 | entropy->next_restart_num++; |
---|
894 | entropy->next_restart_num &= 7; |
---|
895 | } |
---|
896 | entropy->restarts_to_go--; |
---|
897 | } |
---|
898 | |
---|
899 | return TRUE; |
---|
900 | } |
---|
901 | |
---|
902 | |
---|
903 | /* Encode a single block's worth of coefficients */ |
---|
904 | |
---|
905 | LOCAL(boolean) |
---|
906 | encode_one_block (working_state * state, JCOEFPTR block, int last_dc_val, |
---|
907 | c_derived_tbl *dctbl, c_derived_tbl *actbl) |
---|
908 | { |
---|
909 | register int temp, temp2; |
---|
910 | register int nbits; |
---|
911 | register int k, r, i; |
---|
912 | |
---|
913 | /* Encode the DC coefficient difference per section F.1.2.1 */ |
---|
914 | |
---|
915 | temp = temp2 = block[0] - last_dc_val; |
---|
916 | |
---|
917 | if (temp < 0) { |
---|
918 | temp = -temp; /* temp is abs value of input */ |
---|
919 | /* For a negative input, want temp2 = bitwise complement of abs(input) */ |
---|
920 | /* This code assumes we are on a two's complement machine */ |
---|
921 | temp2--; |
---|
922 | } |
---|
923 | |
---|
924 | /* Find the number of bits needed for the magnitude of the coefficient */ |
---|
925 | nbits = 0; |
---|
926 | while (temp) { |
---|
927 | nbits++; |
---|
928 | temp >>= 1; |
---|
929 | } |
---|
930 | /* Check for out-of-range coefficient values. |
---|
931 | * Since we're encoding a difference, the range limit is twice as much. |
---|
932 | */ |
---|
933 | if (nbits > MAX_COEF_BITS+1) |
---|
934 | ERREXIT(state->cinfo, JERR_BAD_DCT_COEF); |
---|
935 | |
---|
936 | /* Emit the Huffman-coded symbol for the number of bits */ |
---|
937 | if (! emit_bits_s(state, dctbl->ehufco[nbits], dctbl->ehufsi[nbits])) |
---|
938 | return FALSE; |
---|
939 | |
---|
940 | /* Emit that number of bits of the value, if positive, */ |
---|
941 | /* or the complement of its magnitude, if negative. */ |
---|
942 | if (nbits) /* emit_bits rejects calls with size 0 */ |
---|
943 | if (! emit_bits_s(state, (unsigned int) temp2, nbits)) |
---|
944 | return FALSE; |
---|
945 | |
---|
946 | /* Encode the AC coefficients per section F.1.2.2 */ |
---|
947 | |
---|
948 | r = 0; /* r = run length of zeros */ |
---|
949 | |
---|
950 | for (k = 1; k < DCTSIZE2; k++) { |
---|
951 | if ((temp = block[jpeg_natural_order[k]]) == 0) { |
---|
952 | r++; |
---|
953 | } else { |
---|
954 | /* if run length > 15, must emit special run-length-16 codes (0xF0) */ |
---|
955 | while (r > 15) { |
---|
956 | if (! emit_bits_s(state, actbl->ehufco[0xF0], actbl->ehufsi[0xF0])) |
---|
957 | return FALSE; |
---|
958 | r -= 16; |
---|
959 | } |
---|
960 | |
---|
961 | temp2 = temp; |
---|
962 | if (temp < 0) { |
---|
963 | temp = -temp; /* temp is abs value of input */ |
---|
964 | /* This code assumes we are on a two's complement machine */ |
---|
965 | temp2--; |
---|
966 | } |
---|
967 | |
---|
968 | /* Find the number of bits needed for the magnitude of the coefficient */ |
---|
969 | nbits = 1; /* there must be at least one 1 bit */ |
---|
970 | while ((temp >>= 1)) |
---|
971 | nbits++; |
---|
972 | /* Check for out-of-range coefficient values */ |
---|
973 | if (nbits > MAX_COEF_BITS) |
---|
974 | ERREXIT(state->cinfo, JERR_BAD_DCT_COEF); |
---|
975 | |
---|
976 | /* Emit Huffman symbol for run length / number of bits */ |
---|
977 | i = (r << 4) + nbits; |
---|
978 | if (! emit_bits_s(state, actbl->ehufco[i], actbl->ehufsi[i])) |
---|
979 | return FALSE; |
---|
980 | |
---|
981 | /* Emit that number of bits of the value, if positive, */ |
---|
982 | /* or the complement of its magnitude, if negative. */ |
---|
983 | if (! emit_bits_s(state, (unsigned int) temp2, nbits)) |
---|
984 | return FALSE; |
---|
985 | |
---|
986 | r = 0; |
---|
987 | } |
---|
988 | } |
---|
989 | |
---|
990 | /* If the last coef(s) were zero, emit an end-of-block code */ |
---|
991 | if (r > 0) |
---|
992 | if (! emit_bits_s(state, actbl->ehufco[0], actbl->ehufsi[0])) |
---|
993 | return FALSE; |
---|
994 | |
---|
995 | return TRUE; |
---|
996 | } |
---|
997 | |
---|
998 | |
---|
999 | /* |
---|
1000 | * Encode and output one MCU's worth of Huffman-compressed coefficients. |
---|
1001 | */ |
---|
1002 | |
---|
1003 | METHODDEF(boolean) |
---|
1004 | encode_mcu_huff (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
---|
1005 | { |
---|
1006 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
---|
1007 | working_state state; |
---|
1008 | int blkn, ci; |
---|
1009 | jpeg_component_info * compptr; |
---|
1010 | |
---|
1011 | /* Load up working state */ |
---|
1012 | state.next_output_byte = cinfo->dest->next_output_byte; |
---|
1013 | state.free_in_buffer = cinfo->dest->free_in_buffer; |
---|
1014 | ASSIGN_STATE(state.cur, entropy->saved); |
---|
1015 | state.cinfo = cinfo; |
---|
1016 | |
---|
1017 | /* Emit restart marker if needed */ |
---|
1018 | if (cinfo->restart_interval) { |
---|
1019 | if (entropy->restarts_to_go == 0) |
---|
1020 | if (! emit_restart_s(&state, entropy->next_restart_num)) |
---|
1021 | return FALSE; |
---|
1022 | } |
---|
1023 | |
---|
1024 | /* Encode the MCU data blocks */ |
---|
1025 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
---|
1026 | ci = cinfo->MCU_membership[blkn]; |
---|
1027 | compptr = cinfo->cur_comp_info[ci]; |
---|
1028 | if (! encode_one_block(&state, |
---|
1029 | MCU_data[blkn][0], state.cur.last_dc_val[ci], |
---|
1030 | entropy->dc_derived_tbls[compptr->dc_tbl_no], |
---|
1031 | entropy->ac_derived_tbls[compptr->ac_tbl_no])) |
---|
1032 | return FALSE; |
---|
1033 | /* Update last_dc_val */ |
---|
1034 | state.cur.last_dc_val[ci] = MCU_data[blkn][0][0]; |
---|
1035 | } |
---|
1036 | |
---|
1037 | /* Completed MCU, so update state */ |
---|
1038 | cinfo->dest->next_output_byte = state.next_output_byte; |
---|
1039 | cinfo->dest->free_in_buffer = state.free_in_buffer; |
---|
1040 | ASSIGN_STATE(entropy->saved, state.cur); |
---|
1041 | |
---|
1042 | /* Update restart-interval state too */ |
---|
1043 | if (cinfo->restart_interval) { |
---|
1044 | if (entropy->restarts_to_go == 0) { |
---|
1045 | entropy->restarts_to_go = cinfo->restart_interval; |
---|
1046 | entropy->next_restart_num++; |
---|
1047 | entropy->next_restart_num &= 7; |
---|
1048 | } |
---|
1049 | entropy->restarts_to_go--; |
---|
1050 | } |
---|
1051 | |
---|
1052 | return TRUE; |
---|
1053 | } |
---|
1054 | |
---|
1055 | |
---|
1056 | /* |
---|
1057 | * Finish up at the end of a Huffman-compressed scan. |
---|
1058 | */ |
---|
1059 | |
---|
1060 | METHODDEF(void) |
---|
1061 | finish_pass_huff (j_compress_ptr cinfo) |
---|
1062 | { |
---|
1063 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
---|
1064 | working_state state; |
---|
1065 | |
---|
1066 | if (cinfo->progressive_mode) { |
---|
1067 | entropy->next_output_byte = cinfo->dest->next_output_byte; |
---|
1068 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; |
---|
1069 | |
---|
1070 | /* Flush out any buffered data */ |
---|
1071 | emit_eobrun(entropy); |
---|
1072 | flush_bits_e(entropy); |
---|
1073 | |
---|
1074 | cinfo->dest->next_output_byte = entropy->next_output_byte; |
---|
1075 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; |
---|
1076 | } else { |
---|
1077 | /* Load up working state ... flush_bits needs it */ |
---|
1078 | state.next_output_byte = cinfo->dest->next_output_byte; |
---|
1079 | state.free_in_buffer = cinfo->dest->free_in_buffer; |
---|
1080 | ASSIGN_STATE(state.cur, entropy->saved); |
---|
1081 | state.cinfo = cinfo; |
---|
1082 | |
---|
1083 | /* Flush out the last data */ |
---|
1084 | if (! flush_bits_s(&state)) |
---|
1085 | ERREXIT(cinfo, JERR_CANT_SUSPEND); |
---|
1086 | |
---|
1087 | /* Update state */ |
---|
1088 | cinfo->dest->next_output_byte = state.next_output_byte; |
---|
1089 | cinfo->dest->free_in_buffer = state.free_in_buffer; |
---|
1090 | ASSIGN_STATE(entropy->saved, state.cur); |
---|
1091 | } |
---|
1092 | } |
---|
1093 | |
---|
1094 | |
---|
1095 | /* |
---|
1096 | * Huffman coding optimization. |
---|
1097 | * |
---|
1098 | * We first scan the supplied data and count the number of uses of each symbol |
---|
1099 | * that is to be Huffman-coded. (This process MUST agree with the code above.) |
---|
1100 | * Then we build a Huffman coding tree for the observed counts. |
---|
1101 | * Symbols which are not needed at all for the particular image are not |
---|
1102 | * assigned any code, which saves space in the DHT marker as well as in |
---|
1103 | * the compressed data. |
---|
1104 | */ |
---|
1105 | |
---|
1106 | |
---|
1107 | /* Process a single block's worth of coefficients */ |
---|
1108 | |
---|
1109 | LOCAL(void) |
---|
1110 | htest_one_block (j_compress_ptr cinfo, JCOEFPTR block, int last_dc_val, |
---|
1111 | long dc_counts[], long ac_counts[]) |
---|
1112 | { |
---|
1113 | register int temp; |
---|
1114 | register int nbits; |
---|
1115 | register int k, r; |
---|
1116 | |
---|
1117 | /* Encode the DC coefficient difference per section F.1.2.1 */ |
---|
1118 | |
---|
1119 | temp = block[0] - last_dc_val; |
---|
1120 | if (temp < 0) |
---|
1121 | temp = -temp; |
---|
1122 | |
---|
1123 | /* Find the number of bits needed for the magnitude of the coefficient */ |
---|
1124 | nbits = 0; |
---|
1125 | while (temp) { |
---|
1126 | nbits++; |
---|
1127 | temp >>= 1; |
---|
1128 | } |
---|
1129 | /* Check for out-of-range coefficient values. |
---|
1130 | * Since we're encoding a difference, the range limit is twice as much. |
---|
1131 | */ |
---|
1132 | if (nbits > MAX_COEF_BITS+1) |
---|
1133 | ERREXIT(cinfo, JERR_BAD_DCT_COEF); |
---|
1134 | |
---|
1135 | /* Count the Huffman symbol for the number of bits */ |
---|
1136 | dc_counts[nbits]++; |
---|
1137 | |
---|
1138 | /* Encode the AC coefficients per section F.1.2.2 */ |
---|
1139 | |
---|
1140 | r = 0; /* r = run length of zeros */ |
---|
1141 | |
---|
1142 | for (k = 1; k < DCTSIZE2; k++) { |
---|
1143 | if ((temp = block[jpeg_natural_order[k]]) == 0) { |
---|
1144 | r++; |
---|
1145 | } else { |
---|
1146 | /* if run length > 15, must emit special run-length-16 codes (0xF0) */ |
---|
1147 | while (r > 15) { |
---|
1148 | ac_counts[0xF0]++; |
---|
1149 | r -= 16; |
---|
1150 | } |
---|
1151 | |
---|
1152 | /* Find the number of bits needed for the magnitude of the coefficient */ |
---|
1153 | if (temp < 0) |
---|
1154 | temp = -temp; |
---|
1155 | |
---|
1156 | /* Find the number of bits needed for the magnitude of the coefficient */ |
---|
1157 | nbits = 1; /* there must be at least one 1 bit */ |
---|
1158 | while ((temp >>= 1)) |
---|
1159 | nbits++; |
---|
1160 | /* Check for out-of-range coefficient values */ |
---|
1161 | if (nbits > MAX_COEF_BITS) |
---|
1162 | ERREXIT(cinfo, JERR_BAD_DCT_COEF); |
---|
1163 | |
---|
1164 | /* Count Huffman symbol for run length / number of bits */ |
---|
1165 | ac_counts[(r << 4) + nbits]++; |
---|
1166 | |
---|
1167 | r = 0; |
---|
1168 | } |
---|
1169 | } |
---|
1170 | |
---|
1171 | /* If the last coef(s) were zero, emit an end-of-block code */ |
---|
1172 | if (r > 0) |
---|
1173 | ac_counts[0]++; |
---|
1174 | } |
---|
1175 | |
---|
1176 | |
---|
1177 | /* |
---|
1178 | * Trial-encode one MCU's worth of Huffman-compressed coefficients. |
---|
1179 | * No data is actually output, so no suspension return is possible. |
---|
1180 | */ |
---|
1181 | |
---|
1182 | METHODDEF(boolean) |
---|
1183 | encode_mcu_gather (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
---|
1184 | { |
---|
1185 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
---|
1186 | int blkn, ci; |
---|
1187 | jpeg_component_info * compptr; |
---|
1188 | |
---|
1189 | /* Take care of restart intervals if needed */ |
---|
1190 | if (cinfo->restart_interval) { |
---|
1191 | if (entropy->restarts_to_go == 0) { |
---|
1192 | /* Re-initialize DC predictions to 0 */ |
---|
1193 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) |
---|
1194 | entropy->saved.last_dc_val[ci] = 0; |
---|
1195 | /* Update restart state */ |
---|
1196 | entropy->restarts_to_go = cinfo->restart_interval; |
---|
1197 | } |
---|
1198 | entropy->restarts_to_go--; |
---|
1199 | } |
---|
1200 | |
---|
1201 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
---|
1202 | ci = cinfo->MCU_membership[blkn]; |
---|
1203 | compptr = cinfo->cur_comp_info[ci]; |
---|
1204 | htest_one_block(cinfo, MCU_data[blkn][0], entropy->saved.last_dc_val[ci], |
---|
1205 | entropy->dc_count_ptrs[compptr->dc_tbl_no], |
---|
1206 | entropy->ac_count_ptrs[compptr->ac_tbl_no]); |
---|
1207 | entropy->saved.last_dc_val[ci] = MCU_data[blkn][0][0]; |
---|
1208 | } |
---|
1209 | |
---|
1210 | return TRUE; |
---|
1211 | } |
---|
1212 | |
---|
1213 | |
---|
1214 | /* |
---|
1215 | * Generate the best Huffman code table for the given counts, fill htbl. |
---|
1216 | * |
---|
1217 | * The JPEG standard requires that no symbol be assigned a codeword of all |
---|
1218 | * one bits (so that padding bits added at the end of a compressed segment |
---|
1219 | * can't look like a valid code). Because of the canonical ordering of |
---|
1220 | * codewords, this just means that there must be an unused slot in the |
---|
1221 | * longest codeword length category. Section K.2 of the JPEG spec suggests |
---|
1222 | * reserving such a slot by pretending that symbol 256 is a valid symbol |
---|
1223 | * with count 1. In theory that's not optimal; giving it count zero but |
---|
1224 | * including it in the symbol set anyway should give a better Huffman code. |
---|
1225 | * But the theoretically better code actually seems to come out worse in |
---|
1226 | * practice, because it produces more all-ones bytes (which incur stuffed |
---|
1227 | * zero bytes in the final file). In any case the difference is tiny. |
---|
1228 | * |
---|
1229 | * The JPEG standard requires Huffman codes to be no more than 16 bits long. |
---|
1230 | * If some symbols have a very small but nonzero probability, the Huffman tree |
---|
1231 | * must be adjusted to meet the code length restriction. We currently use |
---|
1232 | * the adjustment method suggested in JPEG section K.2. This method is *not* |
---|
1233 | * optimal; it may not choose the best possible limited-length code. But |
---|
1234 | * typically only very-low-frequency symbols will be given less-than-optimal |
---|
1235 | * lengths, so the code is almost optimal. Experimental comparisons against |
---|
1236 | * an optimal limited-length-code algorithm indicate that the difference is |
---|
1237 | * microscopic --- usually less than a hundredth of a percent of total size. |
---|
1238 | * So the extra complexity of an optimal algorithm doesn't seem worthwhile. |
---|
1239 | */ |
---|
1240 | |
---|
1241 | LOCAL(void) |
---|
1242 | jpeg_gen_optimal_table (j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[]) |
---|
1243 | { |
---|
1244 | #define MAX_CLEN 32 /* assumed maximum initial code length */ |
---|
1245 | UINT8 bits[MAX_CLEN+1]; /* bits[k] = # of symbols with code length k */ |
---|
1246 | int codesize[257]; /* codesize[k] = code length of symbol k */ |
---|
1247 | int others[257]; /* next symbol in current branch of tree */ |
---|
1248 | int c1, c2; |
---|
1249 | int p, i, j; |
---|
1250 | long v; |
---|
1251 | |
---|
1252 | /* This algorithm is explained in section K.2 of the JPEG standard */ |
---|
1253 | |
---|
1254 | MEMZERO(bits, SIZEOF(bits)); |
---|
1255 | MEMZERO(codesize, SIZEOF(codesize)); |
---|
1256 | for (i = 0; i < 257; i++) |
---|
1257 | others[i] = -1; /* init links to empty */ |
---|
1258 | |
---|
1259 | freq[256] = 1; /* make sure 256 has a nonzero count */ |
---|
1260 | /* Including the pseudo-symbol 256 in the Huffman procedure guarantees |
---|
1261 | * that no real symbol is given code-value of all ones, because 256 |
---|
1262 | * will be placed last in the largest codeword category. |
---|
1263 | */ |
---|
1264 | |
---|
1265 | /* Huffman's basic algorithm to assign optimal code lengths to symbols */ |
---|
1266 | |
---|
1267 | for (;;) { |
---|
1268 | /* Find the smallest nonzero frequency, set c1 = its symbol */ |
---|
1269 | /* In case of ties, take the larger symbol number */ |
---|
1270 | c1 = -1; |
---|
1271 | v = 1000000000L; |
---|
1272 | for (i = 0; i <= 256; i++) { |
---|
1273 | if (freq[i] && freq[i] <= v) { |
---|
1274 | v = freq[i]; |
---|
1275 | c1 = i; |
---|
1276 | } |
---|
1277 | } |
---|
1278 | |
---|
1279 | /* Find the next smallest nonzero frequency, set c2 = its symbol */ |
---|
1280 | /* In case of ties, take the larger symbol number */ |
---|
1281 | c2 = -1; |
---|
1282 | v = 1000000000L; |
---|
1283 | for (i = 0; i <= 256; i++) { |
---|
1284 | if (freq[i] && freq[i] <= v && i != c1) { |
---|
1285 | v = freq[i]; |
---|
1286 | c2 = i; |
---|
1287 | } |
---|
1288 | } |
---|
1289 | |
---|
1290 | /* Done if we've merged everything into one frequency */ |
---|
1291 | if (c2 < 0) |
---|
1292 | break; |
---|
1293 | |
---|
1294 | /* Else merge the two counts/trees */ |
---|
1295 | freq[c1] += freq[c2]; |
---|
1296 | freq[c2] = 0; |
---|
1297 | |
---|
1298 | /* Increment the codesize of everything in c1's tree branch */ |
---|
1299 | codesize[c1]++; |
---|
1300 | while (others[c1] >= 0) { |
---|
1301 | c1 = others[c1]; |
---|
1302 | codesize[c1]++; |
---|
1303 | } |
---|
1304 | |
---|
1305 | others[c1] = c2; /* chain c2 onto c1's tree branch */ |
---|
1306 | |
---|
1307 | /* Increment the codesize of everything in c2's tree branch */ |
---|
1308 | codesize[c2]++; |
---|
1309 | while (others[c2] >= 0) { |
---|
1310 | c2 = others[c2]; |
---|
1311 | codesize[c2]++; |
---|
1312 | } |
---|
1313 | } |
---|
1314 | |
---|
1315 | /* Now count the number of symbols of each code length */ |
---|
1316 | for (i = 0; i <= 256; i++) { |
---|
1317 | if (codesize[i]) { |
---|
1318 | /* The JPEG standard seems to think that this can't happen, */ |
---|
1319 | /* but I'm paranoid... */ |
---|
1320 | if (codesize[i] > MAX_CLEN) |
---|
1321 | ERREXIT(cinfo, JERR_HUFF_CLEN_OVERFLOW); |
---|
1322 | |
---|
1323 | bits[codesize[i]]++; |
---|
1324 | } |
---|
1325 | } |
---|
1326 | |
---|
1327 | /* JPEG doesn't allow symbols with code lengths over 16 bits, so if the pure |
---|
1328 | * Huffman procedure assigned any such lengths, we must adjust the coding. |
---|
1329 | * Here is what the JPEG spec says about how this next bit works: |
---|
1330 | * Since symbols are paired for the longest Huffman code, the symbols are |
---|
1331 | * removed from this length category two at a time. The prefix for the pair |
---|
1332 | * (which is one bit shorter) is allocated to one of the pair; then, |
---|
1333 | * skipping the BITS entry for that prefix length, a code word from the next |
---|
1334 | * shortest nonzero BITS entry is converted into a prefix for two code words |
---|
1335 | * one bit longer. |
---|
1336 | */ |
---|
1337 | |
---|
1338 | for (i = MAX_CLEN; i > 16; i--) { |
---|
1339 | while (bits[i] > 0) { |
---|
1340 | j = i - 2; /* find length of new prefix to be used */ |
---|
1341 | while (bits[j] == 0) |
---|
1342 | j--; |
---|
1343 | |
---|
1344 | bits[i] -= 2; /* remove two symbols */ |
---|
1345 | bits[i-1]++; /* one goes in this length */ |
---|
1346 | bits[j+1] += 2; /* two new symbols in this length */ |
---|
1347 | bits[j]--; /* symbol of this length is now a prefix */ |
---|
1348 | } |
---|
1349 | } |
---|
1350 | |
---|
1351 | /* Remove the count for the pseudo-symbol 256 from the largest codelength */ |
---|
1352 | while (bits[i] == 0) /* find largest codelength still in use */ |
---|
1353 | i--; |
---|
1354 | bits[i]--; |
---|
1355 | |
---|
1356 | /* Return final symbol counts (only for lengths 0..16) */ |
---|
1357 | MEMCOPY(htbl->bits, bits, SIZEOF(htbl->bits)); |
---|
1358 | |
---|
1359 | /* Return a list of the symbols sorted by code length */ |
---|
1360 | /* It's not real clear to me why we don't need to consider the codelength |
---|
1361 | * changes made above, but the JPEG spec seems to think this works. |
---|
1362 | */ |
---|
1363 | p = 0; |
---|
1364 | for (i = 1; i <= MAX_CLEN; i++) { |
---|
1365 | for (j = 0; j <= 255; j++) { |
---|
1366 | if (codesize[j] == i) { |
---|
1367 | htbl->huffval[p] = (UINT8) j; |
---|
1368 | p++; |
---|
1369 | } |
---|
1370 | } |
---|
1371 | } |
---|
1372 | |
---|
1373 | /* Set sent_table FALSE so updated table will be written to JPEG file. */ |
---|
1374 | htbl->sent_table = FALSE; |
---|
1375 | } |
---|
1376 | |
---|
1377 | |
---|
1378 | /* |
---|
1379 | * Finish up a statistics-gathering pass and create the new Huffman tables. |
---|
1380 | */ |
---|
1381 | |
---|
1382 | METHODDEF(void) |
---|
1383 | finish_pass_gather (j_compress_ptr cinfo) |
---|
1384 | { |
---|
1385 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
---|
1386 | int ci, dctbl, actbl, tbl; |
---|
1387 | jpeg_component_info * compptr; |
---|
1388 | JHUFF_TBL **htblptr; |
---|
1389 | boolean did_dc[NUM_HUFF_TBLS]; |
---|
1390 | boolean did_ac[NUM_HUFF_TBLS]; |
---|
1391 | boolean did[NUM_HUFF_TBLS]; |
---|
1392 | |
---|
1393 | /* It's important not to apply jpeg_gen_optimal_table more than once |
---|
1394 | * per table, because it clobbers the input frequency counts! |
---|
1395 | */ |
---|
1396 | if (cinfo->progressive_mode) { |
---|
1397 | /* Flush out buffered data (all we care about is counting the EOB symbol) */ |
---|
1398 | emit_eobrun(entropy); |
---|
1399 | |
---|
1400 | MEMZERO(did, SIZEOF(did)); |
---|
1401 | |
---|
1402 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
---|
1403 | compptr = cinfo->cur_comp_info[ci]; |
---|
1404 | if (cinfo->Ss == 0) { |
---|
1405 | if (cinfo->Ah != 0) /* DC refinement needs no table */ |
---|
1406 | continue; |
---|
1407 | tbl = compptr->dc_tbl_no; |
---|
1408 | } else { |
---|
1409 | tbl = compptr->ac_tbl_no; |
---|
1410 | } |
---|
1411 | if (! did[tbl]) { |
---|
1412 | if (cinfo->Ss == 0) |
---|
1413 | htblptr = & cinfo->dc_huff_tbl_ptrs[tbl]; |
---|
1414 | else |
---|
1415 | htblptr = & cinfo->ac_huff_tbl_ptrs[tbl]; |
---|
1416 | if (*htblptr == NULL) |
---|
1417 | *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); |
---|
1418 | jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]); |
---|
1419 | did[tbl] = TRUE; |
---|
1420 | } |
---|
1421 | } |
---|
1422 | } else { |
---|
1423 | MEMZERO(did_dc, SIZEOF(did_dc)); |
---|
1424 | MEMZERO(did_ac, SIZEOF(did_ac)); |
---|
1425 | |
---|
1426 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
---|
1427 | compptr = cinfo->cur_comp_info[ci]; |
---|
1428 | dctbl = compptr->dc_tbl_no; |
---|
1429 | actbl = compptr->ac_tbl_no; |
---|
1430 | if (! did_dc[dctbl]) { |
---|
1431 | htblptr = & cinfo->dc_huff_tbl_ptrs[dctbl]; |
---|
1432 | if (*htblptr == NULL) |
---|
1433 | *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); |
---|
1434 | jpeg_gen_optimal_table(cinfo, *htblptr, entropy->dc_count_ptrs[dctbl]); |
---|
1435 | did_dc[dctbl] = TRUE; |
---|
1436 | } |
---|
1437 | if (! did_ac[actbl]) { |
---|
1438 | htblptr = & cinfo->ac_huff_tbl_ptrs[actbl]; |
---|
1439 | if (*htblptr == NULL) |
---|
1440 | *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); |
---|
1441 | jpeg_gen_optimal_table(cinfo, *htblptr, entropy->ac_count_ptrs[actbl]); |
---|
1442 | did_ac[actbl] = TRUE; |
---|
1443 | } |
---|
1444 | } |
---|
1445 | } |
---|
1446 | } |
---|
1447 | |
---|
1448 | |
---|
1449 | /* |
---|
1450 | * Initialize for a Huffman-compressed scan. |
---|
1451 | * If gather_statistics is TRUE, we do not output anything during the scan, |
---|
1452 | * just count the Huffman symbols used and generate Huffman code tables. |
---|
1453 | */ |
---|
1454 | |
---|
1455 | METHODDEF(void) |
---|
1456 | start_pass_huff (j_compress_ptr cinfo, boolean gather_statistics) |
---|
1457 | { |
---|
1458 | huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
---|
1459 | int ci, dctbl, actbl, tbl; |
---|
1460 | jpeg_component_info * compptr; |
---|
1461 | |
---|
1462 | if (gather_statistics) |
---|
1463 | entropy->pub.finish_pass = finish_pass_gather; |
---|
1464 | else |
---|
1465 | entropy->pub.finish_pass = finish_pass_huff; |
---|
1466 | |
---|
1467 | if (cinfo->progressive_mode) { |
---|
1468 | entropy->cinfo = cinfo; |
---|
1469 | entropy->gather_statistics = gather_statistics; |
---|
1470 | |
---|
1471 | /* We assume jcmaster.c already validated the scan parameters. */ |
---|
1472 | |
---|
1473 | /* Select execution routine */ |
---|
1474 | if (cinfo->Ah == 0) { |
---|
1475 | if (cinfo->Ss == 0) |
---|
1476 | entropy->pub.encode_mcu = encode_mcu_DC_first; |
---|
1477 | else |
---|
1478 | entropy->pub.encode_mcu = encode_mcu_AC_first; |
---|
1479 | } else { |
---|
1480 | if (cinfo->Ss == 0) |
---|
1481 | entropy->pub.encode_mcu = encode_mcu_DC_refine; |
---|
1482 | else { |
---|
1483 | entropy->pub.encode_mcu = encode_mcu_AC_refine; |
---|
1484 | /* AC refinement needs a correction bit buffer */ |
---|
1485 | if (entropy->bit_buffer == NULL) |
---|
1486 | entropy->bit_buffer = (char *) |
---|
1487 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
---|
1488 | MAX_CORR_BITS * SIZEOF(char)); |
---|
1489 | } |
---|
1490 | } |
---|
1491 | |
---|
1492 | /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1 |
---|
1493 | * for AC coefficients. |
---|
1494 | */ |
---|
1495 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
---|
1496 | compptr = cinfo->cur_comp_info[ci]; |
---|
1497 | /* Initialize DC predictions to 0 */ |
---|
1498 | entropy->saved.last_dc_val[ci] = 0; |
---|
1499 | /* Get table index */ |
---|
1500 | if (cinfo->Ss == 0) { |
---|
1501 | if (cinfo->Ah != 0) /* DC refinement needs no table */ |
---|
1502 | continue; |
---|
1503 | tbl = compptr->dc_tbl_no; |
---|
1504 | } else { |
---|
1505 | entropy->ac_tbl_no = tbl = compptr->ac_tbl_no; |
---|
1506 | } |
---|
1507 | if (gather_statistics) { |
---|
1508 | /* Check for invalid table index */ |
---|
1509 | /* (make_c_derived_tbl does this in the other path) */ |
---|
1510 | if (tbl < 0 || tbl >= NUM_HUFF_TBLS) |
---|
1511 | ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl); |
---|
1512 | /* Allocate and zero the statistics tables */ |
---|
1513 | /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */ |
---|
1514 | if (entropy->count_ptrs[tbl] == NULL) |
---|
1515 | entropy->count_ptrs[tbl] = (long *) |
---|
1516 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
---|
1517 | 257 * SIZEOF(long)); |
---|
1518 | MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long)); |
---|
1519 | } else { |
---|
1520 | /* Compute derived values for Huffman table */ |
---|
1521 | /* We may do this more than once for a table, but it's not expensive */ |
---|
1522 | jpeg_make_c_derived_tbl(cinfo, cinfo->Ss == 0, tbl, |
---|
1523 | & entropy->derived_tbls[tbl]); |
---|
1524 | } |
---|
1525 | } |
---|
1526 | |
---|
1527 | /* Initialize AC stuff */ |
---|
1528 | entropy->EOBRUN = 0; |
---|
1529 | entropy->BE = 0; |
---|
1530 | } else { |
---|
1531 | if (gather_statistics) |
---|
1532 | entropy->pub.encode_mcu = encode_mcu_gather; |
---|
1533 | else |
---|
1534 | entropy->pub.encode_mcu = encode_mcu_huff; |
---|
1535 | |
---|
1536 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
---|
1537 | compptr = cinfo->cur_comp_info[ci]; |
---|
1538 | dctbl = compptr->dc_tbl_no; |
---|
1539 | actbl = compptr->ac_tbl_no; |
---|
1540 | if (gather_statistics) { |
---|
1541 | /* Check for invalid table indexes */ |
---|
1542 | /* (make_c_derived_tbl does this in the other path) */ |
---|
1543 | if (dctbl < 0 || dctbl >= NUM_HUFF_TBLS) |
---|
1544 | ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, dctbl); |
---|
1545 | if (actbl < 0 || actbl >= NUM_HUFF_TBLS) |
---|
1546 | ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, actbl); |
---|
1547 | /* Allocate and zero the statistics tables */ |
---|
1548 | /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */ |
---|
1549 | if (entropy->dc_count_ptrs[dctbl] == NULL) |
---|
1550 | entropy->dc_count_ptrs[dctbl] = (long *) |
---|
1551 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
---|
1552 | 257 * SIZEOF(long)); |
---|
1553 | MEMZERO(entropy->dc_count_ptrs[dctbl], 257 * SIZEOF(long)); |
---|
1554 | if (entropy->ac_count_ptrs[actbl] == NULL) |
---|
1555 | entropy->ac_count_ptrs[actbl] = (long *) |
---|
1556 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
---|
1557 | 257 * SIZEOF(long)); |
---|
1558 | MEMZERO(entropy->ac_count_ptrs[actbl], 257 * SIZEOF(long)); |
---|
1559 | } else { |
---|
1560 | /* Compute derived values for Huffman tables */ |
---|
1561 | /* We may do this more than once for a table, but it's not expensive */ |
---|
1562 | jpeg_make_c_derived_tbl(cinfo, TRUE, dctbl, |
---|
1563 | & entropy->dc_derived_tbls[dctbl]); |
---|
1564 | jpeg_make_c_derived_tbl(cinfo, FALSE, actbl, |
---|
1565 | & entropy->ac_derived_tbls[actbl]); |
---|
1566 | } |
---|
1567 | /* Initialize DC predictions to 0 */ |
---|
1568 | entropy->saved.last_dc_val[ci] = 0; |
---|
1569 | } |
---|
1570 | } |
---|
1571 | |
---|
1572 | /* Initialize bit buffer to empty */ |
---|
1573 | entropy->saved.put_buffer = 0; |
---|
1574 | entropy->saved.put_bits = 0; |
---|
1575 | |
---|
1576 | /* Initialize restart stuff */ |
---|
1577 | entropy->restarts_to_go = cinfo->restart_interval; |
---|
1578 | entropy->next_restart_num = 0; |
---|
1579 | } |
---|
1580 | |
---|
1581 | |
---|
1582 | /* |
---|
1583 | * Module initialization routine for Huffman entropy encoding. |
---|
1584 | */ |
---|
1585 | |
---|
1586 | GLOBAL(void) |
---|
1587 | jinit_huff_encoder (j_compress_ptr cinfo) |
---|
1588 | { |
---|
1589 | huff_entropy_ptr entropy; |
---|
1590 | int i; |
---|
1591 | |
---|
1592 | entropy = (huff_entropy_ptr) |
---|
1593 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
---|
1594 | SIZEOF(huff_entropy_encoder)); |
---|
1595 | cinfo->entropy = (struct jpeg_entropy_encoder *) entropy; |
---|
1596 | entropy->pub.start_pass = start_pass_huff; |
---|
1597 | |
---|
1598 | if (cinfo->progressive_mode) { |
---|
1599 | /* Mark tables unallocated */ |
---|
1600 | for (i = 0; i < NUM_HUFF_TBLS; i++) { |
---|
1601 | entropy->derived_tbls[i] = NULL; |
---|
1602 | entropy->count_ptrs[i] = NULL; |
---|
1603 | } |
---|
1604 | entropy->bit_buffer = NULL; /* needed only in AC refinement scan */ |
---|
1605 | } else { |
---|
1606 | /* Mark tables unallocated */ |
---|
1607 | for (i = 0; i < NUM_HUFF_TBLS; i++) { |
---|
1608 | entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL; |
---|
1609 | entropy->dc_count_ptrs[i] = entropy->ac_count_ptrs[i] = NULL; |
---|
1610 | } |
---|
1611 | } |
---|
1612 | } |
---|