1 | /* |
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2 | * jccoefct.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 compression. |
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9 | * This controller is the top level of the JPEG compressor proper. |
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10 | * The coefficient buffer lies between forward-DCT and entropy encoding steps. |
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11 | */ |
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12 | |
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13 | #define JPEG_INTERNALS |
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14 | #include "jinclude.h" |
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15 | #include "jpeglib.h" |
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16 | |
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17 | |
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18 | /* We use a full-image coefficient buffer when doing Huffman optimization, |
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19 | * and also for writing multiple-scan JPEG files. In all cases, the DCT |
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20 | * step is run during the first pass, and subsequent passes need only read |
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21 | * the buffered coefficients. |
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22 | */ |
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23 | #ifdef ENTROPY_OPT_SUPPORTED |
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24 | #define FULL_COEF_BUFFER_SUPPORTED |
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25 | #else |
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26 | #ifdef C_MULTISCAN_FILES_SUPPORTED |
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27 | #define FULL_COEF_BUFFER_SUPPORTED |
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28 | #endif |
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29 | #endif |
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30 | |
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31 | |
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32 | /* Private buffer controller object */ |
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33 | |
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34 | typedef struct { |
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35 | struct jpeg_c_coef_controller pub; /* public fields */ |
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36 | |
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37 | JDIMENSION iMCU_row_num; /* iMCU row # within image */ |
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38 | JDIMENSION mcu_ctr; /* counts MCUs processed in current row */ |
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39 | int MCU_vert_offset; /* counts MCU rows within iMCU row */ |
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40 | int MCU_rows_per_iMCU_row; /* number of such rows needed */ |
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41 | |
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42 | /* For single-pass compression, it's sufficient to buffer just one MCU |
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43 | * (although this may prove a bit slow in practice). We allocate a |
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44 | * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for each |
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45 | * MCU constructed and sent. (On 80x86, the workspace is FAR even though |
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46 | * it's not really very big; this is to keep the module interfaces unchanged |
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47 | * when a large coefficient buffer is necessary.) |
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48 | * In multi-pass modes, this array points to the current MCU's blocks |
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49 | * within the virtual arrays. |
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50 | */ |
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51 | JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU]; |
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52 | |
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53 | /* In multi-pass modes, we need a virtual block array for each component. */ |
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54 | jvirt_barray_ptr whole_image[MAX_COMPONENTS]; |
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55 | } my_coef_controller; |
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56 | |
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57 | typedef my_coef_controller * my_coef_ptr; |
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58 | |
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59 | |
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60 | /* Forward declarations */ |
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61 | METHODDEF(boolean) compress_data |
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62 | JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf)); |
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63 | #ifdef FULL_COEF_BUFFER_SUPPORTED |
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64 | METHODDEF(boolean) compress_first_pass |
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65 | JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf)); |
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66 | METHODDEF(boolean) compress_output |
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67 | JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf)); |
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68 | #endif |
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69 | |
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70 | |
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71 | LOCAL(void) |
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72 | start_iMCU_row (j_compress_ptr cinfo) |
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73 | /* Reset within-iMCU-row counters for a new row */ |
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74 | { |
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75 | my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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76 | |
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77 | /* In an interleaved scan, an MCU row is the same as an iMCU row. |
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78 | * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows. |
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79 | * But at the bottom of the image, process only what's left. |
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80 | */ |
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81 | if (cinfo->comps_in_scan > 1) { |
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82 | coef->MCU_rows_per_iMCU_row = 1; |
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83 | } else { |
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84 | if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1)) |
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85 | coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor; |
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86 | else |
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87 | coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height; |
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88 | } |
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89 | |
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90 | coef->mcu_ctr = 0; |
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91 | coef->MCU_vert_offset = 0; |
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92 | } |
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93 | |
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94 | |
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95 | /* |
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96 | * Initialize for a processing pass. |
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97 | */ |
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98 | |
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99 | METHODDEF(void) |
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100 | start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode) |
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101 | { |
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102 | my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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103 | |
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104 | coef->iMCU_row_num = 0; |
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105 | start_iMCU_row(cinfo); |
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106 | |
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107 | switch (pass_mode) { |
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108 | case JBUF_PASS_THRU: |
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109 | if (coef->whole_image[0] != NULL) |
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110 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
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111 | coef->pub.compress_data = compress_data; |
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112 | break; |
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113 | #ifdef FULL_COEF_BUFFER_SUPPORTED |
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114 | case JBUF_SAVE_AND_PASS: |
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115 | if (coef->whole_image[0] == NULL) |
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116 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
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117 | coef->pub.compress_data = compress_first_pass; |
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118 | break; |
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119 | case JBUF_CRANK_DEST: |
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120 | if (coef->whole_image[0] == NULL) |
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121 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
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122 | coef->pub.compress_data = compress_output; |
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123 | break; |
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124 | #endif |
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125 | default: |
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126 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
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127 | break; |
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128 | } |
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129 | } |
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130 | |
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131 | |
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132 | /* |
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133 | * Process some data in the single-pass case. |
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134 | * We process the equivalent of one fully interleaved MCU row ("iMCU" row) |
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135 | * per call, ie, v_samp_factor block rows for each component in the image. |
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136 | * Returns TRUE if the iMCU row is completed, FALSE if suspended. |
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137 | * |
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138 | * NB: input_buf contains a plane for each component in image, |
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139 | * which we index according to the component's SOF position. |
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140 | */ |
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141 | |
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142 | METHODDEF(boolean) |
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143 | compress_data (j_compress_ptr cinfo, JSAMPIMAGE input_buf) |
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144 | { |
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145 | my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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146 | JDIMENSION MCU_col_num; /* index of current MCU within row */ |
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147 | JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1; |
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148 | JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; |
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149 | int blkn, bi, ci, yindex, yoffset, blockcnt; |
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150 | JDIMENSION ypos, xpos; |
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151 | jpeg_component_info *compptr; |
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152 | |
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153 | /* Loop to write as much as one whole iMCU row */ |
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154 | for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; |
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155 | yoffset++) { |
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156 | for (MCU_col_num = coef->mcu_ctr; MCU_col_num <= last_MCU_col; |
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157 | MCU_col_num++) { |
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158 | /* Determine where data comes from in input_buf and do the DCT thing. |
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159 | * Each call on forward_DCT processes a horizontal row of DCT blocks |
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160 | * as wide as an MCU; we rely on having allocated the MCU_buffer[] blocks |
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161 | * sequentially. Dummy blocks at the right or bottom edge are filled in |
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162 | * specially. The data in them does not matter for image reconstruction, |
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163 | * so we fill them with values that will encode to the smallest amount of |
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164 | * data, viz: all zeroes in the AC entries, DC entries equal to previous |
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165 | * block's DC value. (Thanks to Thomas Kinsman for this idea.) |
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166 | */ |
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167 | blkn = 0; |
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168 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
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169 | compptr = cinfo->cur_comp_info[ci]; |
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170 | blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width |
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171 | : compptr->last_col_width; |
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172 | xpos = MCU_col_num * compptr->MCU_sample_width; |
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173 | ypos = yoffset * DCTSIZE; /* ypos == (yoffset+yindex) * DCTSIZE */ |
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174 | for (yindex = 0; yindex < compptr->MCU_height; yindex++) { |
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175 | if (coef->iMCU_row_num < last_iMCU_row || |
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176 | yoffset+yindex < compptr->last_row_height) { |
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177 | (*cinfo->fdct->forward_DCT) (cinfo, compptr, |
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178 | input_buf[compptr->component_index], |
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179 | coef->MCU_buffer[blkn], |
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180 | ypos, xpos, (JDIMENSION) blockcnt); |
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181 | if (blockcnt < compptr->MCU_width) { |
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182 | /* Create some dummy blocks at the right edge of the image. */ |
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183 | jzero_far((void FAR *) coef->MCU_buffer[blkn + blockcnt], |
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184 | (compptr->MCU_width - blockcnt) * SIZEOF(JBLOCK)); |
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185 | for (bi = blockcnt; bi < compptr->MCU_width; bi++) { |
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186 | coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn+bi-1][0][0]; |
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187 | } |
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188 | } |
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189 | } else { |
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190 | /* Create a row of dummy blocks at the bottom of the image. */ |
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191 | jzero_far((void FAR *) coef->MCU_buffer[blkn], |
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192 | compptr->MCU_width * SIZEOF(JBLOCK)); |
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193 | for (bi = 0; bi < compptr->MCU_width; bi++) { |
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194 | coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn-1][0][0]; |
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195 | } |
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196 | } |
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197 | blkn += compptr->MCU_width; |
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198 | ypos += DCTSIZE; |
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199 | } |
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200 | } |
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201 | /* Try to write the MCU. In event of a suspension failure, we will |
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202 | * re-DCT the MCU on restart (a bit inefficient, could be fixed...) |
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203 | */ |
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204 | if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) { |
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205 | /* Suspension forced; update state counters and exit */ |
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206 | coef->MCU_vert_offset = yoffset; |
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207 | coef->mcu_ctr = MCU_col_num; |
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208 | return FALSE; |
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209 | } |
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210 | } |
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211 | /* Completed an MCU row, but perhaps not an iMCU row */ |
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212 | coef->mcu_ctr = 0; |
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213 | } |
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214 | /* Completed the iMCU row, advance counters for next one */ |
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215 | coef->iMCU_row_num++; |
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216 | start_iMCU_row(cinfo); |
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217 | return TRUE; |
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218 | } |
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219 | |
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220 | |
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221 | #ifdef FULL_COEF_BUFFER_SUPPORTED |
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222 | |
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223 | /* |
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224 | * Process some data in the first pass of a multi-pass case. |
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225 | * We process the equivalent of one fully interleaved MCU row ("iMCU" row) |
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226 | * per call, ie, v_samp_factor block rows for each component in the image. |
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227 | * This amount of data is read from the source buffer, DCT'd and quantized, |
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228 | * and saved into the virtual arrays. We also generate suitable dummy blocks |
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229 | * as needed at the right and lower edges. (The dummy blocks are constructed |
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230 | * in the virtual arrays, which have been padded appropriately.) This makes |
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231 | * it possible for subsequent passes not to worry about real vs. dummy blocks. |
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232 | * |
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233 | * We must also emit the data to the entropy encoder. This is conveniently |
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234 | * done by calling compress_output() after we've loaded the current strip |
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235 | * of the virtual arrays. |
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236 | * |
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237 | * NB: input_buf contains a plane for each component in image. All |
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238 | * components are DCT'd and loaded into the virtual arrays in this pass. |
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239 | * However, it may be that only a subset of the components are emitted to |
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240 | * the entropy encoder during this first pass; be careful about looking |
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241 | * at the scan-dependent variables (MCU dimensions, etc). |
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242 | */ |
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243 | |
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244 | METHODDEF(boolean) |
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245 | compress_first_pass (j_compress_ptr cinfo, JSAMPIMAGE input_buf) |
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246 | { |
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247 | my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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248 | JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1; |
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249 | JDIMENSION blocks_across, MCUs_across, MCUindex; |
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250 | int bi, ci, h_samp_factor, block_row, block_rows, ndummy; |
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251 | JCOEF lastDC; |
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252 | jpeg_component_info *compptr; |
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253 | JBLOCKARRAY buffer; |
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254 | JBLOCKROW thisblockrow, lastblockrow; |
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255 | |
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256 | for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
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257 | ci++, compptr++) { |
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258 | /* Align the virtual buffer for this component. */ |
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259 | buffer = (*cinfo->mem->access_virt_barray) |
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260 | ((j_common_ptr) cinfo, coef->whole_image[ci], |
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261 | coef->iMCU_row_num * compptr->v_samp_factor, |
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262 | (JDIMENSION) compptr->v_samp_factor, TRUE); |
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263 | /* Count non-dummy DCT block rows in this iMCU row. */ |
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264 | if (coef->iMCU_row_num < last_iMCU_row) |
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265 | block_rows = compptr->v_samp_factor; |
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266 | else { |
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267 | /* NB: can't use last_row_height here, since may not be set! */ |
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268 | block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor); |
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269 | if (block_rows == 0) block_rows = compptr->v_samp_factor; |
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270 | } |
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271 | blocks_across = compptr->width_in_blocks; |
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272 | h_samp_factor = compptr->h_samp_factor; |
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273 | /* Count number of dummy blocks to be added at the right margin. */ |
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274 | ndummy = (int) (blocks_across % h_samp_factor); |
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275 | if (ndummy > 0) |
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276 | ndummy = h_samp_factor - ndummy; |
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277 | /* Perform DCT for all non-dummy blocks in this iMCU row. Each call |
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278 | * on forward_DCT processes a complete horizontal row of DCT blocks. |
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279 | */ |
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280 | for (block_row = 0; block_row < block_rows; block_row++) { |
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281 | thisblockrow = buffer[block_row]; |
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282 | (*cinfo->fdct->forward_DCT) (cinfo, compptr, |
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283 | input_buf[ci], thisblockrow, |
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284 | (JDIMENSION) (block_row * DCTSIZE), |
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285 | (JDIMENSION) 0, blocks_across); |
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286 | if (ndummy > 0) { |
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287 | /* Create dummy blocks at the right edge of the image. */ |
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288 | thisblockrow += blocks_across; /* => first dummy block */ |
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289 | jzero_far((void FAR *) thisblockrow, ndummy * SIZEOF(JBLOCK)); |
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290 | lastDC = thisblockrow[-1][0]; |
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291 | for (bi = 0; bi < ndummy; bi++) { |
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292 | thisblockrow[bi][0] = lastDC; |
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293 | } |
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294 | } |
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295 | } |
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296 | /* If at end of image, create dummy block rows as needed. |
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297 | * The tricky part here is that within each MCU, we want the DC values |
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298 | * of the dummy blocks to match the last real block's DC value. |
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299 | * This squeezes a few more bytes out of the resulting file... |
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300 | */ |
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301 | if (coef->iMCU_row_num == last_iMCU_row) { |
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302 | blocks_across += ndummy; /* include lower right corner */ |
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303 | MCUs_across = blocks_across / h_samp_factor; |
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304 | for (block_row = block_rows; block_row < compptr->v_samp_factor; |
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305 | block_row++) { |
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306 | thisblockrow = buffer[block_row]; |
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307 | lastblockrow = buffer[block_row-1]; |
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308 | jzero_far((void FAR *) thisblockrow, |
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309 | (size_t) (blocks_across * SIZEOF(JBLOCK))); |
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310 | for (MCUindex = 0; MCUindex < MCUs_across; MCUindex++) { |
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311 | lastDC = lastblockrow[h_samp_factor-1][0]; |
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312 | for (bi = 0; bi < h_samp_factor; bi++) { |
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313 | thisblockrow[bi][0] = lastDC; |
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314 | } |
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315 | thisblockrow += h_samp_factor; /* advance to next MCU in row */ |
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316 | lastblockrow += h_samp_factor; |
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317 | } |
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318 | } |
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319 | } |
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320 | } |
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321 | /* NB: compress_output will increment iMCU_row_num if successful. |
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322 | * A suspension return will result in redoing all the work above next time. |
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323 | */ |
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324 | |
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325 | /* Emit data to the entropy encoder, sharing code with subsequent passes */ |
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326 | return compress_output(cinfo, input_buf); |
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327 | } |
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328 | |
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329 | |
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330 | /* |
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331 | * Process some data in subsequent passes of a multi-pass case. |
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332 | * We process the equivalent of one fully interleaved MCU row ("iMCU" row) |
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333 | * per call, ie, v_samp_factor block rows for each component in the scan. |
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334 | * The data is obtained from the virtual arrays and fed to the entropy coder. |
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335 | * Returns TRUE if the iMCU row is completed, FALSE if suspended. |
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336 | * |
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337 | * NB: input_buf is ignored; it is likely to be a NULL pointer. |
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338 | */ |
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339 | |
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340 | METHODDEF(boolean) |
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341 | compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf) |
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342 | { |
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343 | my_coef_ptr coef = (my_coef_ptr) cinfo->coef; |
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344 | JDIMENSION MCU_col_num; /* index of current MCU within row */ |
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345 | int blkn, ci, xindex, yindex, yoffset; |
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346 | JDIMENSION start_col; |
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347 | JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN]; |
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348 | JBLOCKROW buffer_ptr; |
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349 | jpeg_component_info *compptr; |
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350 | |
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351 | /* Align the virtual buffers for the components used in this scan. |
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352 | * NB: during first pass, this is safe only because the buffers will |
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353 | * already be aligned properly, so jmemmgr.c won't need to do any I/O. |
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354 | */ |
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355 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
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356 | compptr = cinfo->cur_comp_info[ci]; |
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357 | buffer[ci] = (*cinfo->mem->access_virt_barray) |
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358 | ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index], |
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359 | coef->iMCU_row_num * compptr->v_samp_factor, |
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360 | (JDIMENSION) compptr->v_samp_factor, FALSE); |
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361 | } |
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362 | |
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363 | /* Loop to process one whole iMCU row */ |
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364 | for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row; |
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365 | yoffset++) { |
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366 | for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row; |
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367 | MCU_col_num++) { |
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368 | /* Construct list of pointers to DCT blocks belonging to this MCU */ |
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369 | blkn = 0; /* index of current DCT block within MCU */ |
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370 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { |
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371 | compptr = cinfo->cur_comp_info[ci]; |
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372 | start_col = MCU_col_num * compptr->MCU_width; |
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373 | for (yindex = 0; yindex < compptr->MCU_height; yindex++) { |
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374 | buffer_ptr = buffer[ci][yindex+yoffset] + start_col; |
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375 | for (xindex = 0; xindex < compptr->MCU_width; xindex++) { |
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376 | coef->MCU_buffer[blkn++] = buffer_ptr++; |
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377 | } |
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378 | } |
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379 | } |
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380 | /* Try to write the MCU. */ |
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381 | if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) { |
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382 | /* Suspension forced; update state counters and exit */ |
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383 | coef->MCU_vert_offset = yoffset; |
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384 | coef->mcu_ctr = MCU_col_num; |
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385 | return FALSE; |
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386 | } |
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387 | } |
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388 | /* Completed an MCU row, but perhaps not an iMCU row */ |
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389 | coef->mcu_ctr = 0; |
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390 | } |
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391 | /* Completed the iMCU row, advance counters for next one */ |
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392 | coef->iMCU_row_num++; |
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393 | start_iMCU_row(cinfo); |
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394 | return TRUE; |
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395 | } |
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396 | |
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397 | #endif /* FULL_COEF_BUFFER_SUPPORTED */ |
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398 | |
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399 | |
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400 | /* |
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401 | * Initialize coefficient buffer controller. |
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402 | */ |
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403 | |
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404 | GLOBAL(void) |
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405 | jinit_c_coef_controller (j_compress_ptr cinfo, boolean need_full_buffer) |
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406 | { |
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407 | my_coef_ptr coef; |
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408 | |
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409 | coef = (my_coef_ptr) |
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410 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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411 | SIZEOF(my_coef_controller)); |
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412 | cinfo->coef = (struct jpeg_c_coef_controller *) coef; |
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413 | coef->pub.start_pass = start_pass_coef; |
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414 | |
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415 | /* Create the coefficient buffer. */ |
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416 | if (need_full_buffer) { |
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417 | #ifdef FULL_COEF_BUFFER_SUPPORTED |
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418 | /* Allocate a full-image virtual array for each component, */ |
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419 | /* padded to a multiple of samp_factor DCT blocks in each direction. */ |
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420 | int ci; |
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421 | jpeg_component_info *compptr; |
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422 | |
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423 | for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
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424 | ci++, compptr++) { |
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425 | coef->whole_image[ci] = (*cinfo->mem->request_virt_barray) |
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426 | ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE, |
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427 | (JDIMENSION) jround_up((long) compptr->width_in_blocks, |
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428 | (long) compptr->h_samp_factor), |
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429 | (JDIMENSION) jround_up((long) compptr->height_in_blocks, |
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430 | (long) compptr->v_samp_factor), |
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431 | (JDIMENSION) compptr->v_samp_factor); |
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432 | } |
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433 | #else |
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434 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
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435 | #endif |
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436 | } else { |
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437 | /* We only need a single-MCU buffer. */ |
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438 | JBLOCKROW buffer; |
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439 | int i; |
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440 | |
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441 | buffer = (JBLOCKROW) |
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442 | (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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443 | C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)); |
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444 | for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) { |
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445 | coef->MCU_buffer[i] = buffer + i; |
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446 | } |
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447 | coef->whole_image[0] = NULL; /* flag for no virtual arrays */ |
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448 | } |
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449 | } |
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