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