1 | /* |
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2 | * jdapistd.c |
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3 | * |
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4 | * Copyright (C) 1994-1996, 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 application interface code for the decompression half |
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9 | * of the JPEG library. These are the "standard" API routines that are |
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10 | * used in the normal full-decompression case. They are not used by a |
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11 | * transcoding-only application. Note that if an application links in |
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12 | * jpeg_start_decompress, it will end up linking in the entire decompressor. |
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13 | * We thus must separate this file from jdapimin.c to avoid linking the |
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14 | * whole decompression library into a transcoder. |
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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 | |
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22 | /* Forward declarations */ |
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23 | LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo)); |
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24 | |
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25 | |
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26 | /* |
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27 | * Decompression initialization. |
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28 | * jpeg_read_header must be completed before calling this. |
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29 | * |
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30 | * If a multipass operating mode was selected, this will do all but the |
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31 | * last pass, and thus may take a great deal of time. |
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32 | * |
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33 | * Returns FALSE if suspended. The return value need be inspected only if |
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34 | * a suspending data source is used. |
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35 | */ |
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36 | |
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37 | GLOBAL(boolean) |
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38 | jpeg_start_decompress (j_decompress_ptr cinfo) |
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39 | { |
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40 | if (cinfo->global_state == DSTATE_READY) { |
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41 | /* First call: initialize master control, select active modules */ |
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42 | jinit_master_decompress(cinfo); |
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43 | if (cinfo->buffered_image) { |
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44 | /* No more work here; expecting jpeg_start_output next */ |
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45 | cinfo->global_state = DSTATE_BUFIMAGE; |
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46 | return TRUE; |
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47 | } |
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48 | cinfo->global_state = DSTATE_PRELOAD; |
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49 | } |
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50 | if (cinfo->global_state == DSTATE_PRELOAD) { |
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51 | /* If file has multiple scans, absorb them all into the coef buffer */ |
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52 | if (cinfo->inputctl->has_multiple_scans) { |
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53 | #ifdef D_MULTISCAN_FILES_SUPPORTED |
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54 | for (;;) { |
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55 | int retcode; |
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56 | /* Call progress monitor hook if present */ |
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57 | if (cinfo->progress != NULL) |
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58 | (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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59 | /* Absorb some more input */ |
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60 | retcode = (*cinfo->inputctl->consume_input) (cinfo); |
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61 | if (retcode == JPEG_SUSPENDED) |
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62 | return FALSE; |
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63 | if (retcode == JPEG_REACHED_EOI) |
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64 | break; |
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65 | /* Advance progress counter if appropriate */ |
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66 | if (cinfo->progress != NULL && |
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67 | (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) { |
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68 | if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) { |
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69 | /* jdmaster underestimated number of scans; ratchet up one scan */ |
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70 | cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows; |
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71 | } |
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72 | } |
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73 | } |
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74 | #else |
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75 | ERREXIT(cinfo, JERR_NOT_COMPILED); |
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76 | #endif /* D_MULTISCAN_FILES_SUPPORTED */ |
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77 | } |
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78 | cinfo->output_scan_number = cinfo->input_scan_number; |
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79 | } else if (cinfo->global_state != DSTATE_PRESCAN) |
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80 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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81 | /* Perform any dummy output passes, and set up for the final pass */ |
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82 | return output_pass_setup(cinfo); |
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83 | } |
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84 | |
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85 | |
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86 | /* |
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87 | * Set up for an output pass, and perform any dummy pass(es) needed. |
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88 | * Common subroutine for jpeg_start_decompress and jpeg_start_output. |
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89 | * Entry: global_state = DSTATE_PRESCAN only if previously suspended. |
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90 | * Exit: If done, returns TRUE and sets global_state for proper output mode. |
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91 | * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN. |
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92 | */ |
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93 | |
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94 | LOCAL(boolean) |
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95 | output_pass_setup (j_decompress_ptr cinfo) |
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96 | { |
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97 | if (cinfo->global_state != DSTATE_PRESCAN) { |
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98 | /* First call: do pass setup */ |
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99 | (*cinfo->master->prepare_for_output_pass) (cinfo); |
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100 | cinfo->output_scanline = 0; |
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101 | cinfo->global_state = DSTATE_PRESCAN; |
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102 | } |
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103 | /* Loop over any required dummy passes */ |
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104 | while (cinfo->master->is_dummy_pass) { |
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105 | #ifdef QUANT_2PASS_SUPPORTED |
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106 | /* Crank through the dummy pass */ |
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107 | while (cinfo->output_scanline < cinfo->output_height) { |
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108 | JDIMENSION last_scanline; |
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109 | /* Call progress monitor hook if present */ |
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110 | if (cinfo->progress != NULL) { |
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111 | cinfo->progress->pass_counter = (long) cinfo->output_scanline; |
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112 | cinfo->progress->pass_limit = (long) cinfo->output_height; |
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113 | (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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114 | } |
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115 | /* Process some data */ |
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116 | last_scanline = cinfo->output_scanline; |
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117 | (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL, |
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118 | &cinfo->output_scanline, (JDIMENSION) 0); |
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119 | if (cinfo->output_scanline == last_scanline) |
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120 | return FALSE; /* No progress made, must suspend */ |
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121 | } |
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122 | /* Finish up dummy pass, and set up for another one */ |
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123 | (*cinfo->master->finish_output_pass) (cinfo); |
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124 | (*cinfo->master->prepare_for_output_pass) (cinfo); |
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125 | cinfo->output_scanline = 0; |
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126 | #else |
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127 | ERREXIT(cinfo, JERR_NOT_COMPILED); |
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128 | #endif /* QUANT_2PASS_SUPPORTED */ |
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129 | } |
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130 | /* Ready for application to drive output pass through |
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131 | * jpeg_read_scanlines or jpeg_read_raw_data. |
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132 | */ |
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133 | cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING; |
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134 | return TRUE; |
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135 | } |
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136 | |
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137 | |
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138 | /* |
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139 | * Read some scanlines of data from the JPEG decompressor. |
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140 | * |
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141 | * The return value will be the number of lines actually read. |
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142 | * This may be less than the number requested in several cases, |
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143 | * including bottom of image, data source suspension, and operating |
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144 | * modes that emit multiple scanlines at a time. |
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145 | * |
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146 | * Note: we warn about excess calls to jpeg_read_scanlines() since |
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147 | * this likely signals an application programmer error. However, |
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148 | * an oversize buffer (max_lines > scanlines remaining) is not an error. |
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149 | */ |
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150 | |
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151 | GLOBAL(JDIMENSION) |
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152 | jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines, |
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153 | JDIMENSION max_lines) |
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154 | { |
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155 | JDIMENSION row_ctr; |
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156 | |
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157 | if (cinfo->global_state != DSTATE_SCANNING) |
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158 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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159 | if (cinfo->output_scanline >= cinfo->output_height) { |
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160 | WARNMS(cinfo, JWRN_TOO_MUCH_DATA); |
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161 | return 0; |
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162 | } |
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163 | |
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164 | /* Call progress monitor hook if present */ |
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165 | if (cinfo->progress != NULL) { |
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166 | cinfo->progress->pass_counter = (long) cinfo->output_scanline; |
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167 | cinfo->progress->pass_limit = (long) cinfo->output_height; |
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168 | (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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169 | } |
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170 | |
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171 | /* Process some data */ |
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172 | row_ctr = 0; |
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173 | (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines); |
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174 | cinfo->output_scanline += row_ctr; |
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175 | return row_ctr; |
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176 | } |
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177 | |
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178 | |
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179 | /* |
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180 | * Alternate entry point to read raw data. |
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181 | * Processes exactly one iMCU row per call, unless suspended. |
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182 | */ |
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183 | |
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184 | GLOBAL(JDIMENSION) |
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185 | jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data, |
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186 | JDIMENSION max_lines) |
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187 | { |
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188 | JDIMENSION lines_per_iMCU_row; |
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189 | |
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190 | if (cinfo->global_state != DSTATE_RAW_OK) |
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191 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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192 | if (cinfo->output_scanline >= cinfo->output_height) { |
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193 | WARNMS(cinfo, JWRN_TOO_MUCH_DATA); |
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194 | return 0; |
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195 | } |
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196 | |
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197 | /* Call progress monitor hook if present */ |
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198 | if (cinfo->progress != NULL) { |
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199 | cinfo->progress->pass_counter = (long) cinfo->output_scanline; |
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200 | cinfo->progress->pass_limit = (long) cinfo->output_height; |
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201 | (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo); |
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202 | } |
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203 | |
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204 | /* Verify that at least one iMCU row can be returned. */ |
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205 | lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_v_scaled_size; |
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206 | if (max_lines < lines_per_iMCU_row) |
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207 | ERREXIT(cinfo, JERR_BUFFER_SIZE); |
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208 | |
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209 | /* Decompress directly into user's buffer. */ |
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210 | if (! (*cinfo->coef->decompress_data) (cinfo, data)) |
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211 | return 0; /* suspension forced, can do nothing more */ |
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212 | |
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213 | /* OK, we processed one iMCU row. */ |
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214 | cinfo->output_scanline += lines_per_iMCU_row; |
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215 | return lines_per_iMCU_row; |
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216 | } |
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217 | |
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218 | |
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219 | /* Additional entry points for buffered-image mode. */ |
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220 | |
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221 | #ifdef D_MULTISCAN_FILES_SUPPORTED |
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222 | |
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223 | /* |
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224 | * Initialize for an output pass in buffered-image mode. |
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225 | */ |
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226 | |
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227 | GLOBAL(boolean) |
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228 | jpeg_start_output (j_decompress_ptr cinfo, int scan_number) |
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229 | { |
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230 | if (cinfo->global_state != DSTATE_BUFIMAGE && |
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231 | cinfo->global_state != DSTATE_PRESCAN) |
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232 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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233 | /* Limit scan number to valid range */ |
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234 | if (scan_number <= 0) |
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235 | scan_number = 1; |
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236 | if (cinfo->inputctl->eoi_reached && |
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237 | scan_number > cinfo->input_scan_number) |
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238 | scan_number = cinfo->input_scan_number; |
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239 | cinfo->output_scan_number = scan_number; |
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240 | /* Perform any dummy output passes, and set up for the real pass */ |
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241 | return output_pass_setup(cinfo); |
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242 | } |
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243 | |
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244 | |
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245 | /* |
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246 | * Finish up after an output pass in buffered-image mode. |
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247 | * |
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248 | * Returns FALSE if suspended. The return value need be inspected only if |
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249 | * a suspending data source is used. |
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250 | */ |
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251 | |
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252 | GLOBAL(boolean) |
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253 | jpeg_finish_output (j_decompress_ptr cinfo) |
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254 | { |
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255 | if ((cinfo->global_state == DSTATE_SCANNING || |
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256 | cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) { |
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257 | /* Terminate this pass. */ |
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258 | /* We do not require the whole pass to have been completed. */ |
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259 | (*cinfo->master->finish_output_pass) (cinfo); |
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260 | cinfo->global_state = DSTATE_BUFPOST; |
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261 | } else if (cinfo->global_state != DSTATE_BUFPOST) { |
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262 | /* BUFPOST = repeat call after a suspension, anything else is error */ |
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263 | ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); |
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264 | } |
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265 | /* Read markers looking for SOS or EOI */ |
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266 | while (cinfo->input_scan_number <= cinfo->output_scan_number && |
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267 | ! cinfo->inputctl->eoi_reached) { |
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268 | if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) |
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269 | return FALSE; /* Suspend, come back later */ |
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270 | } |
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271 | cinfo->global_state = DSTATE_BUFIMAGE; |
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272 | return TRUE; |
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273 | } |
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274 | |
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275 | #endif /* D_MULTISCAN_FILES_SUPPORTED */ |
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