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1 /* |
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2 * jdcoefct.c |
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3 * |
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4 * Copyright (C) 1994-1997, Thomas G. Lane. |
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5 * This file is part of the Independent JPEG Group's software. |
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6 * For conditions of distribution and use, see the accompanying README file. |
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7 * |
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8 * This file contains the coefficient buffer controller for decompression. |
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9 * This controller is the top level of the JPEG decompressor proper. |
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10 * The coefficient buffer lies between entropy decoding and inverse-DCT steps. |
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11 * |
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12 * In buffered-image mode, this controller is the interface between |
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13 * input-oriented processing and output-oriented processing. |
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14 * Also, the input side (only) is used when reading a file for transcoding. |
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15 */ |
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16 |
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17 #define JPEG_INTERNALS |
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18 #include "jinclude.h" |
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19 #include "jpeglib.h" |
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20 |
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21 /* Block smoothing is only applicable for progressive JPEG, so: */ |
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22 #ifndef D_PROGRESSIVE_SUPPORTED |
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23 #undef BLOCK_SMOOTHING_SUPPORTED |
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24 #endif |
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25 |
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26 /* Private buffer controller object */ |
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27 |
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28 typedef struct { |
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29 struct jpeg_d_coef_controller pub; /* public fields */ |
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30 |
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31 /* These variables keep track of the current location of the input side. */ |
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32 /* cinfo->input_iMCU_row is also used for this. */ |
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33 JDIMENSION MCU_ctr; /* counts MCUs processed in current row */ |
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34 int MCU_vert_offset; /* counts MCU rows within iMCU row */ |
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35 int MCU_rows_per_iMCU_row; /* number of such rows needed */ |
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36 |
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37 /* The output side's location is represented by cinfo->output_iMCU_row. */ |
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38 |
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39 /* In single-pass modes, it's sufficient to buffer just one MCU. |
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40 * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks, |
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41 * and let the entropy decoder write into that workspace each time. |
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42 * (On 80x86, the workspace is FAR even though it's not really very big; |
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43 * this is to keep the module interfaces unchanged when a large coefficient |
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44 * buffer is necessary.) |
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45 * In multi-pass modes, this array points to the current MCU's blocks |
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46 * within the virtual arrays; it is used only by the input side. |
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47 */ |
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48 JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU]; |
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49 |
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50 #ifdef D_MULTISCAN_FILES_SUPPORTED |
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51 /* In multi-pass modes, we need a virtual block array for each component. */ |
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52 jvirt_barray_ptr whole_image[MAX_COMPONENTS]; |
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53 #endif |
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54 |
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55 #ifdef BLOCK_SMOOTHING_SUPPORTED |
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56 /* When doing block smoothing, we latch coefficient Al values here */ |
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57 int * coef_bits_latch; |
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58 #define SAVED_COEFS 6 /* we save coef_bits[0..5] */ |
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59 #endif |
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60 } my_coef_controller; |
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61 |
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62 typedef my_coef_controller * my_coef_ptr; |
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63 |
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64 /* Forward declarations */ |
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65 METHODDEF(int) decompress_onepass |
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66 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); |
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67 #ifdef D_MULTISCAN_FILES_SUPPORTED |
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68 METHODDEF(int) decompress_data |
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69 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); |
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70 #endif |
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71 #ifdef BLOCK_SMOOTHING_SUPPORTED |
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72 LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo)); |
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73 METHODDEF(int) decompress_smooth_data |
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74 JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf)); |
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75 #endif |
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76 |
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77 |
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78 LOCAL(void) |
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79 start_iMCU_row (j_decompress_ptr cinfo) |
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80 /* Reset within-iMCU-row counters for a new row (input side) */ |
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81 { |
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82 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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83 |
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84 /* In an interleaved scan, an MCU row is the same as an iMCU row. |
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85 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows. |
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86 * But at the bottom of the image, process only what's left. |
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87 */ |
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88 if (cinfo->comps_in_scan > 1) { |
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89 coef->MCU_rows_per_iMCU_row = 1; |
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90 } else { |
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91 if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1)) |
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92 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor; |
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93 else |
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94 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height; |
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95 } |
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96 |
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97 coef->MCU_ctr = 0; |
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98 coef->MCU_vert_offset = 0; |
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99 } |
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100 |
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101 |
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102 /* |
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103 * Initialize for an input processing pass. |
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104 */ |
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105 |
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106 METHODDEF(void) |
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107 start_input_pass (j_decompress_ptr cinfo) |
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108 { |
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109 cinfo->input_iMCU_row = 0; |
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110 start_iMCU_row(cinfo); |
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111 } |
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112 |
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113 |
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114 /* |
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115 * Initialize for an output processing pass. |
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116 */ |
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117 |
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118 METHODDEF(void) |
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119 start_output_pass (j_decompress_ptr cinfo) |
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120 { |
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121 #ifdef BLOCK_SMOOTHING_SUPPORTED |
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122 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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123 |
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124 /* If multipass, check to see whether to use block smoothing on this pass */ |
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125 if (coef->pub.coef_arrays != NULL) { |
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126 if (cinfo->do_block_smoothing && smoothing_ok(cinfo)) |
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127 coef->pub.decompress_data = decompress_smooth_data; |
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128 else |
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129 coef->pub.decompress_data = decompress_data; |
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130 } |
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131 #endif |
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132 cinfo->output_iMCU_row = 0; |
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133 } |
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134 |
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135 |
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136 /* |
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137 * Decompress and return some data in the single-pass case. |
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138 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). |
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139 * Input and output must run in lockstep since we have only a one-MCU buffer. |
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140 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. |
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141 * |
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142 * NB: output_buf contains a plane for each component in image, |
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143 * which we index according to the component's SOF position. |
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144 */ |
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145 |
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146 METHODDEF(int) |
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147 decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) |
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148 { |
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149 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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150 JDIMENSION MCU_col_num; /* index of current MCU within row */ |
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151 JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; |
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152 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; |
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153 int blkn, ci, xindex, yindex, yoffset, useful_width; |
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154 JSAMPARRAY output_ptr; |
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155 JDIMENSION start_col, output_col; |
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156 jpeg_component_info *compptr; |
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157 inverse_DCT_method_ptr inverse_DCT; |
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158 |
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159 /* Loop to process as much as one whole iMCU row */ |
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160 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; |
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161 yoffset++) { |
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162 for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col; |
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163 MCU_col_num++) { |
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164 /* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */ |
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165 jzero_far((void FAR *) coef->MCU_buffer[0], |
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166 (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK))); |
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167 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { |
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168 /* Suspension forced; update state counters and exit */ |
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169 coef->MCU_vert_offset = yoffset; |
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170 coef->MCU_ctr = MCU_col_num; |
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171 return JPEG_SUSPENDED; |
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172 } |
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173 /* Determine where data should go in output_buf and do the IDCT thing. |
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174 * We skip dummy blocks at the right and bottom edges (but blkn gets |
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175 * incremented past them!). Note the inner loop relies on having |
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176 * allocated the MCU_buffer[] blocks sequentially. |
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177 */ |
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178 blkn = 0; /* index of current DCT block within MCU */ |
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179 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
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180 compptr = cinfo->cur_comp_info[ci]; |
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181 /* Don't bother to IDCT an uninteresting component. */ |
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182 if (! compptr->component_needed) { |
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183 blkn += compptr->MCU_blocks; |
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184 continue; |
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185 } |
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186 inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index]; |
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187 useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width |
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188 : compptr->last_col_width; |
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189 output_ptr = output_buf[compptr->component_index] + |
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190 yoffset * compptr->DCT_scaled_size; |
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191 start_col = MCU_col_num * compptr->MCU_sample_width; |
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192 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { |
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193 if (cinfo->input_iMCU_row < last_iMCU_row || |
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194 yoffset+yindex < compptr->last_row_height) { |
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195 output_col = start_col; |
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196 for (xindex = 0; xindex < useful_width; xindex++) { |
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197 (*inverse_DCT) (cinfo, compptr, |
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198 (JCOEFPTR) coef->MCU_buffer[blkn+xindex], |
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199 output_ptr, output_col); |
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200 output_col += compptr->DCT_scaled_size; |
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201 } |
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202 } |
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203 blkn += compptr->MCU_width; |
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204 output_ptr += compptr->DCT_scaled_size; |
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205 } |
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206 } |
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207 } |
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208 /* Completed an MCU row, but perhaps not an iMCU row */ |
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209 coef->MCU_ctr = 0; |
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210 } |
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211 /* Completed the iMCU row, advance counters for next one */ |
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212 cinfo->output_iMCU_row++; |
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213 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { |
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214 start_iMCU_row(cinfo); |
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215 return JPEG_ROW_COMPLETED; |
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216 } |
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217 /* Completed the scan */ |
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218 (*cinfo->inputctl->finish_input_pass) (cinfo); |
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219 return JPEG_SCAN_COMPLETED; |
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220 } |
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221 |
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222 |
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223 /* |
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224 * Dummy consume-input routine for single-pass operation. |
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225 */ |
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226 |
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227 METHODDEF(int) |
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228 dummy_consume_data (j_decompress_ptr cinfo) |
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229 { |
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230 return JPEG_SUSPENDED; /* Always indicate nothing was done */ |
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231 } |
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232 |
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233 |
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234 #ifdef D_MULTISCAN_FILES_SUPPORTED |
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235 |
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236 /* |
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237 * Consume input data and store it in the full-image coefficient buffer. |
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238 * We read as much as one fully interleaved MCU row ("iMCU" row) per call, |
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239 * ie, v_samp_factor block rows for each component in the scan. |
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240 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. |
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241 */ |
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242 |
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243 METHODDEF(int) |
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244 consume_data (j_decompress_ptr cinfo) |
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245 { |
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246 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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247 JDIMENSION MCU_col_num; /* index of current MCU within row */ |
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248 int blkn, ci, xindex, yindex, yoffset; |
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249 JDIMENSION start_col; |
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250 JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN]; |
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251 JBLOCKROW buffer_ptr; |
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252 jpeg_component_info *compptr; |
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253 |
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254 /* Align the virtual buffers for the components used in this scan. */ |
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255 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
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256 compptr = cinfo->cur_comp_info[ci]; |
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257 buffer[ci] = (*cinfo->mem->access_virt_barray) |
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258 ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index], |
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259 cinfo->input_iMCU_row * compptr->v_samp_factor, |
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260 (JDIMENSION) compptr->v_samp_factor, TRUE); |
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261 /* Note: entropy decoder expects buffer to be zeroed, |
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262 * but this is handled automatically by the memory manager |
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263 * because we requested a pre-zeroed array. |
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264 */ |
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265 } |
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266 |
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267 /* Loop to process one whole iMCU row */ |
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268 for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; |
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269 yoffset++) { |
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270 for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row; |
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271 MCU_col_num++) { |
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272 /* Construct list of pointers to DCT blocks belonging to this MCU */ |
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273 blkn = 0; /* index of current DCT block within MCU */ |
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274 for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
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275 compptr = cinfo->cur_comp_info[ci]; |
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276 start_col = MCU_col_num * compptr->MCU_width; |
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277 for (yindex = 0; yindex < compptr->MCU_height; yindex++) { |
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278 buffer_ptr = buffer[ci][yindex+yoffset] + start_col; |
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279 for (xindex = 0; xindex < compptr->MCU_width; xindex++) { |
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280 coef->MCU_buffer[blkn++] = buffer_ptr++; |
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281 } |
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282 } |
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283 } |
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284 /* Try to fetch the MCU. */ |
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285 if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) { |
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286 /* Suspension forced; update state counters and exit */ |
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287 coef->MCU_vert_offset = yoffset; |
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288 coef->MCU_ctr = MCU_col_num; |
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289 return JPEG_SUSPENDED; |
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290 } |
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291 } |
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292 /* Completed an MCU row, but perhaps not an iMCU row */ |
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293 coef->MCU_ctr = 0; |
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294 } |
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295 /* Completed the iMCU row, advance counters for next one */ |
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296 if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) { |
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297 start_iMCU_row(cinfo); |
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298 return JPEG_ROW_COMPLETED; |
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299 } |
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300 /* Completed the scan */ |
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301 (*cinfo->inputctl->finish_input_pass) (cinfo); |
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302 return JPEG_SCAN_COMPLETED; |
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303 } |
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304 |
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305 |
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306 /* |
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307 * Decompress and return some data in the multi-pass case. |
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308 * Always attempts to emit one fully interleaved MCU row ("iMCU" row). |
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309 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED. |
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310 * |
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311 * NB: output_buf contains a plane for each component in image. |
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312 */ |
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313 |
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314 METHODDEF(int) |
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315 decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) |
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316 { |
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317 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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318 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; |
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319 JDIMENSION block_num; |
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320 int ci, block_row, block_rows; |
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321 JBLOCKARRAY buffer; |
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322 JBLOCKROW buffer_ptr; |
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323 JSAMPARRAY output_ptr; |
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324 JDIMENSION output_col; |
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325 jpeg_component_info *compptr; |
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326 inverse_DCT_method_ptr inverse_DCT; |
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327 |
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328 /* Force some input to be done if we are getting ahead of the input. */ |
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329 while (cinfo->input_scan_number < cinfo->output_scan_number || |
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330 (cinfo->input_scan_number == cinfo->output_scan_number && |
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331 cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) { |
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332 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) |
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333 return JPEG_SUSPENDED; |
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334 } |
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335 |
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336 /* OK, output from the virtual arrays. */ |
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337 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
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338 ci++, compptr++) { |
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339 /* Don't bother to IDCT an uninteresting component. */ |
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340 if (! compptr->component_needed) |
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341 continue; |
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342 /* Align the virtual buffer for this component. */ |
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343 buffer = (*cinfo->mem->access_virt_barray) |
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344 ((j_common_ptr) cinfo, coef->whole_image[ci], |
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345 cinfo->output_iMCU_row * compptr->v_samp_factor, |
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346 (JDIMENSION) compptr->v_samp_factor, FALSE); |
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347 /* Count non-dummy DCT block rows in this iMCU row. */ |
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348 if (cinfo->output_iMCU_row < last_iMCU_row) |
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349 block_rows = compptr->v_samp_factor; |
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350 else { |
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351 /* NB: can't use last_row_height here; it is input-side-dependent! */ |
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352 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); |
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353 if (block_rows == 0) block_rows = compptr->v_samp_factor; |
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354 } |
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355 inverse_DCT = cinfo->idct->inverse_DCT[ci]; |
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356 output_ptr = output_buf[ci]; |
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357 /* Loop over all DCT blocks to be processed. */ |
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358 for (block_row = 0; block_row < block_rows; block_row++) { |
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359 buffer_ptr = buffer[block_row]; |
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360 output_col = 0; |
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361 for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) { |
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362 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr, |
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363 output_ptr, output_col); |
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364 buffer_ptr++; |
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365 output_col += compptr->DCT_scaled_size; |
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366 } |
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367 output_ptr += compptr->DCT_scaled_size; |
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368 } |
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369 } |
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370 |
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371 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) |
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372 return JPEG_ROW_COMPLETED; |
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373 return JPEG_SCAN_COMPLETED; |
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374 } |
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375 |
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376 #endif /* D_MULTISCAN_FILES_SUPPORTED */ |
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377 |
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378 |
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379 #ifdef BLOCK_SMOOTHING_SUPPORTED |
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380 |
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381 /* |
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382 * This code applies interblock smoothing as described by section K.8 |
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383 * of the JPEG standard: the first 5 AC coefficients are estimated from |
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384 * the DC values of a DCT block and its 8 neighboring blocks. |
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385 * We apply smoothing only for progressive JPEG decoding, and only if |
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386 * the coefficients it can estimate are not yet known to full precision. |
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387 */ |
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388 |
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389 /* Natural-order array positions of the first 5 zigzag-order coefficients */ |
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390 #define Q01_POS 1 |
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391 #define Q10_POS 8 |
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392 #define Q20_POS 16 |
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393 #define Q11_POS 9 |
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394 #define Q02_POS 2 |
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395 |
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396 /* |
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397 * Determine whether block smoothing is applicable and safe. |
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398 * We also latch the current states of the coef_bits[] entries for the |
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399 * AC coefficients; otherwise, if the input side of the decompressor |
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400 * advances into a new scan, we might think the coefficients are known |
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401 * more accurately than they really are. |
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402 */ |
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403 |
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404 LOCAL(boolean) |
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405 smoothing_ok (j_decompress_ptr cinfo) |
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406 { |
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407 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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408 boolean smoothing_useful = FALSE; |
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409 int ci, coefi; |
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410 jpeg_component_info *compptr; |
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411 JQUANT_TBL * qtable; |
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412 int * coef_bits; |
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413 int * coef_bits_latch; |
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414 |
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415 if (! cinfo->progressive_mode || cinfo->coef_bits == NULL) |
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416 return FALSE; |
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417 |
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418 /* Allocate latch area if not already done */ |
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419 if (coef->coef_bits_latch == NULL) |
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420 coef->coef_bits_latch = (int *) |
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421 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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422 cinfo->num_components * |
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423 (SAVED_COEFS * SIZEOF(int))); |
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424 coef_bits_latch = coef->coef_bits_latch; |
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425 |
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426 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
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427 ci++, compptr++) { |
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428 /* All components' quantization values must already be latched. */ |
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429 if ((qtable = compptr->quant_table) == NULL) |
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430 return FALSE; |
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431 /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */ |
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432 if (qtable->quantval[0] == 0 || |
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433 qtable->quantval[Q01_POS] == 0 || |
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434 qtable->quantval[Q10_POS] == 0 || |
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435 qtable->quantval[Q20_POS] == 0 || |
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436 qtable->quantval[Q11_POS] == 0 || |
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437 qtable->quantval[Q02_POS] == 0) |
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438 return FALSE; |
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439 /* DC values must be at least partly known for all components. */ |
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440 coef_bits = cinfo->coef_bits[ci]; |
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441 if (coef_bits[0] < 0) |
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442 return FALSE; |
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443 /* Block smoothing is helpful if some AC coefficients remain inaccurate. */ |
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444 for (coefi = 1; coefi <= 5; coefi++) { |
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445 coef_bits_latch[coefi] = coef_bits[coefi]; |
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446 if (coef_bits[coefi] != 0) |
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447 smoothing_useful = TRUE; |
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448 } |
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449 coef_bits_latch += SAVED_COEFS; |
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450 } |
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451 |
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452 return smoothing_useful; |
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453 } |
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454 |
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455 |
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456 /* |
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457 * Variant of decompress_data for use when doing block smoothing. |
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458 */ |
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459 |
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460 METHODDEF(int) |
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461 decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf) |
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462 { |
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463 my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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464 JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; |
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465 JDIMENSION block_num, last_block_column; |
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466 int ci, block_row, block_rows, access_rows; |
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467 JBLOCKARRAY buffer; |
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468 JBLOCKROW buffer_ptr, prev_block_row, next_block_row; |
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469 JSAMPARRAY output_ptr; |
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470 JDIMENSION output_col; |
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471 jpeg_component_info *compptr; |
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472 inverse_DCT_method_ptr inverse_DCT; |
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473 boolean first_row, last_row; |
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474 JBLOCK workspace; |
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475 int *coef_bits; |
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476 JQUANT_TBL *quanttbl; |
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477 INT32 Q00,Q01,Q02,Q10,Q11,Q20, num; |
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478 int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9; |
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479 int Al, pred; |
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480 |
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481 /* Force some input to be done if we are getting ahead of the input. */ |
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482 while (cinfo->input_scan_number <= cinfo->output_scan_number && |
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483 ! cinfo->inputctl->eoi_reached) { |
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484 if (cinfo->input_scan_number == cinfo->output_scan_number) { |
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485 /* If input is working on current scan, we ordinarily want it to |
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486 * have completed the current row. But if input scan is DC, |
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487 * we want it to keep one row ahead so that next block row's DC |
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488 * values are up to date. |
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489 */ |
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490 JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0; |
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491 if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta) |
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492 break; |
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493 } |
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494 if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED) |
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495 return JPEG_SUSPENDED; |
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496 } |
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497 |
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498 /* OK, output from the virtual arrays. */ |
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499 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
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500 ci++, compptr++) { |
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501 /* Don't bother to IDCT an uninteresting component. */ |
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502 if (! compptr->component_needed) |
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503 continue; |
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504 /* Count non-dummy DCT block rows in this iMCU row. */ |
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505 if (cinfo->output_iMCU_row < last_iMCU_row) { |
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506 block_rows = compptr->v_samp_factor; |
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507 access_rows = block_rows * 2; /* this and next iMCU row */ |
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508 last_row = FALSE; |
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509 } else { |
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510 /* NB: can't use last_row_height here; it is input-side-dependent! */ |
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511 block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); |
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512 if (block_rows == 0) block_rows = compptr->v_samp_factor; |
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513 access_rows = block_rows; /* this iMCU row only */ |
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514 last_row = TRUE; |
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515 } |
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516 /* Align the virtual buffer for this component. */ |
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517 if (cinfo->output_iMCU_row > 0) { |
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518 access_rows += compptr->v_samp_factor; /* prior iMCU row too */ |
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519 buffer = (*cinfo->mem->access_virt_barray) |
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520 ((j_common_ptr) cinfo, coef->whole_image[ci], |
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521 (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor, |
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522 (JDIMENSION) access_rows, FALSE); |
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523 buffer += compptr->v_samp_factor; /* point to current iMCU row */ |
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524 first_row = FALSE; |
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525 } else { |
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526 buffer = (*cinfo->mem->access_virt_barray) |
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527 ((j_common_ptr) cinfo, coef->whole_image[ci], |
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528 (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE); |
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529 first_row = TRUE; |
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530 } |
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531 /* Fetch component-dependent info */ |
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532 coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS); |
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533 quanttbl = compptr->quant_table; |
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534 Q00 = quanttbl->quantval[0]; |
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535 Q01 = quanttbl->quantval[Q01_POS]; |
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536 Q10 = quanttbl->quantval[Q10_POS]; |
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537 Q20 = quanttbl->quantval[Q20_POS]; |
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538 Q11 = quanttbl->quantval[Q11_POS]; |
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539 Q02 = quanttbl->quantval[Q02_POS]; |
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540 inverse_DCT = cinfo->idct->inverse_DCT[ci]; |
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541 output_ptr = output_buf[ci]; |
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542 /* Loop over all DCT blocks to be processed. */ |
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543 for (block_row = 0; block_row < block_rows; block_row++) { |
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544 buffer_ptr = buffer[block_row]; |
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545 if (first_row && block_row == 0) |
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546 prev_block_row = buffer_ptr; |
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547 else |
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548 prev_block_row = buffer[block_row-1]; |
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549 if (last_row && block_row == block_rows-1) |
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550 next_block_row = buffer_ptr; |
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551 else |
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552 next_block_row = buffer[block_row+1]; |
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553 /* We fetch the surrounding DC values using a sliding-register approach. |
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554 * Initialize all nine here so as to do the right thing on narrow pics. |
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555 */ |
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556 DC1 = DC2 = DC3 = (int) prev_block_row[0][0]; |
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557 DC4 = DC5 = DC6 = (int) buffer_ptr[0][0]; |
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558 DC7 = DC8 = DC9 = (int) next_block_row[0][0]; |
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559 output_col = 0; |
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560 last_block_column = compptr->width_in_blocks - 1; |
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561 for (block_num = 0; block_num <= last_block_column; block_num++) { |
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562 /* Fetch current DCT block into workspace so we can modify it. */ |
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563 jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1); |
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564 /* Update DC values */ |
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565 if (block_num < last_block_column) { |
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566 DC3 = (int) prev_block_row[1][0]; |
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567 DC6 = (int) buffer_ptr[1][0]; |
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568 DC9 = (int) next_block_row[1][0]; |
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569 } |
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570 /* Compute coefficient estimates per K.8. |
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571 * An estimate is applied only if coefficient is still zero, |
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572 * and is not known to be fully accurate. |
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573 */ |
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574 /* AC01 */ |
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575 if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) { |
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576 num = 36 * Q00 * (DC4 - DC6); |
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577 if (num >= 0) { |
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578 pred = (int) (((Q01<<7) + num) / (Q01<<8)); |
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579 if (Al > 0 && pred >= (1<<Al)) |
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580 pred = (1<<Al)-1; |
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581 } else { |
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582 pred = (int) (((Q01<<7) - num) / (Q01<<8)); |
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583 if (Al > 0 && pred >= (1<<Al)) |
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584 pred = (1<<Al)-1; |
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585 pred = -pred; |
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586 } |
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587 workspace[1] = (JCOEF) pred; |
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588 } |
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589 /* AC10 */ |
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590 if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) { |
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591 num = 36 * Q00 * (DC2 - DC8); |
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592 if (num >= 0) { |
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593 pred = (int) (((Q10<<7) + num) / (Q10<<8)); |
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594 if (Al > 0 && pred >= (1<<Al)) |
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595 pred = (1<<Al)-1; |
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596 } else { |
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597 pred = (int) (((Q10<<7) - num) / (Q10<<8)); |
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598 if (Al > 0 && pred >= (1<<Al)) |
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599 pred = (1<<Al)-1; |
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600 pred = -pred; |
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601 } |
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602 workspace[8] = (JCOEF) pred; |
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603 } |
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604 /* AC20 */ |
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605 if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) { |
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606 num = 9 * Q00 * (DC2 + DC8 - 2*DC5); |
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607 if (num >= 0) { |
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608 pred = (int) (((Q20<<7) + num) / (Q20<<8)); |
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609 if (Al > 0 && pred >= (1<<Al)) |
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610 pred = (1<<Al)-1; |
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611 } else { |
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612 pred = (int) (((Q20<<7) - num) / (Q20<<8)); |
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613 if (Al > 0 && pred >= (1<<Al)) |
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614 pred = (1<<Al)-1; |
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615 pred = -pred; |
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616 } |
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617 workspace[16] = (JCOEF) pred; |
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618 } |
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619 /* AC11 */ |
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620 if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) { |
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621 num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9); |
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622 if (num >= 0) { |
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623 pred = (int) (((Q11<<7) + num) / (Q11<<8)); |
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624 if (Al > 0 && pred >= (1<<Al)) |
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625 pred = (1<<Al)-1; |
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626 } else { |
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627 pred = (int) (((Q11<<7) - num) / (Q11<<8)); |
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628 if (Al > 0 && pred >= (1<<Al)) |
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629 pred = (1<<Al)-1; |
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630 pred = -pred; |
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631 } |
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632 workspace[9] = (JCOEF) pred; |
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633 } |
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634 /* AC02 */ |
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635 if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) { |
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636 num = 9 * Q00 * (DC4 + DC6 - 2*DC5); |
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637 if (num >= 0) { |
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638 pred = (int) (((Q02<<7) + num) / (Q02<<8)); |
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639 if (Al > 0 && pred >= (1<<Al)) |
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640 pred = (1<<Al)-1; |
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641 } else { |
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642 pred = (int) (((Q02<<7) - num) / (Q02<<8)); |
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643 if (Al > 0 && pred >= (1<<Al)) |
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644 pred = (1<<Al)-1; |
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645 pred = -pred; |
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646 } |
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647 workspace[2] = (JCOEF) pred; |
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648 } |
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649 /* OK, do the IDCT */ |
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650 (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace, |
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651 output_ptr, output_col); |
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652 /* Advance for next column */ |
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653 DC1 = DC2; DC2 = DC3; |
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654 DC4 = DC5; DC5 = DC6; |
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655 DC7 = DC8; DC8 = DC9; |
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656 buffer_ptr++, prev_block_row++, next_block_row++; |
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657 output_col += compptr->DCT_scaled_size; |
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658 } |
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659 output_ptr += compptr->DCT_scaled_size; |
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660 } |
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661 } |
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662 |
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663 if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows) |
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664 return JPEG_ROW_COMPLETED; |
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665 return JPEG_SCAN_COMPLETED; |
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666 } |
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667 |
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668 #endif /* BLOCK_SMOOTHING_SUPPORTED */ |
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669 |
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670 |
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671 /* |
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672 * Initialize coefficient buffer controller. |
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673 */ |
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674 |
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675 GLOBAL(void) |
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676 jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer) |
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677 { |
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678 my_coef_ptr coef; |
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679 |
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680 coef = (my_coef_ptr) |
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681 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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682 SIZEOF(my_coef_controller)); |
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683 cinfo->coef = (struct jpeg_d_coef_controller *) coef; |
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684 coef->pub.start_input_pass = start_input_pass; |
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685 coef->pub.start_output_pass = start_output_pass; |
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686 #ifdef BLOCK_SMOOTHING_SUPPORTED |
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687 coef->coef_bits_latch = NULL; |
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688 #endif |
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689 |
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690 /* Create the coefficient buffer. */ |
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691 if (need_full_buffer) { |
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692 #ifdef D_MULTISCAN_FILES_SUPPORTED |
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693 /* Allocate a full-image virtual array for each component, */ |
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694 /* padded to a multiple of samp_factor DCT blocks in each direction. */ |
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695 /* Note we ask for a pre-zeroed array. */ |
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696 int ci, access_rows; |
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697 jpeg_component_info *compptr; |
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698 |
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699 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
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700 ci++, compptr++) { |
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701 access_rows = compptr->v_samp_factor; |
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702 #ifdef BLOCK_SMOOTHING_SUPPORTED |
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703 /* If block smoothing could be used, need a bigger window */ |
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704 if (cinfo->progressive_mode) |
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705 access_rows *= 3; |
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706 #endif |
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707 coef->whole_image[ci] = (*cinfo->mem->request_virt_barray) |
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708 ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE, |
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709 (JDIMENSION) jround_up((long) compptr->width_in_blocks, |
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710 (long) compptr->h_samp_factor), |
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711 (JDIMENSION) jround_up((long) compptr->height_in_blocks, |
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712 (long) compptr->v_samp_factor), |
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713 (JDIMENSION) access_rows); |
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714 } |
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715 coef->pub.consume_data = consume_data; |
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716 coef->pub.decompress_data = decompress_data; |
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717 coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */ |
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718 #else |
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719 ERREXIT(cinfo, JERR_NOT_COMPILED); |
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720 #endif |
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721 } else { |
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722 /* We only need a single-MCU buffer. */ |
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723 JBLOCKROW buffer; |
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724 int i; |
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725 |
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726 buffer = (JBLOCKROW) |
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727 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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728 D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)); |
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729 for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) { |
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730 coef->MCU_buffer[i] = buffer + i; |
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731 } |
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732 coef->pub.consume_data = dummy_consume_data; |
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733 coef->pub.decompress_data = decompress_onepass; |
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734 coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */ |
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735 } |
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736 } |