| 1 | /* |
| 2 | * jdmainct.c |
| 3 | * |
| 4 | * Copyright (C) 1994-1996, Thomas G. Lane. |
| 5 | * This file is part of the Independent JPEG Group's software. |
| 6 | * For conditions of distribution and use, see the accompanying README file. |
| 7 | * |
| 8 | * This file contains the main buffer controller for decompression. |
| 9 | * The main buffer lies between the JPEG decompressor proper and the |
| 10 | * post-processor; it holds downsampled data in the JPEG colorspace. |
| 11 | * |
| 12 | * Note that this code is bypassed in raw-data mode, since the application |
| 13 | * supplies the equivalent of the main buffer in that case. |
| 14 | */ |
| 15 | |
| 16 | #define JPEG_INTERNALS |
| 17 | #include "jinclude.h" |
| 18 | #include "jpeglib.h" |
| 19 | |
| 20 | |
| 21 | /* |
| 22 | * In the current system design, the main buffer need never be a full-image |
| 23 | * buffer; any full-height buffers will be found inside the coefficient or |
| 24 | * postprocessing controllers. Nonetheless, the main controller is not |
| 25 | * trivial. Its responsibility is to provide context rows for upsampling/ |
| 26 | * rescaling, and doing this in an efficient fashion is a bit tricky. |
| 27 | * |
| 28 | * Postprocessor input data is counted in "row groups". A row group |
| 29 | * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size) |
| 30 | * sample rows of each component. (We require DCT_scaled_size values to be |
| 31 | * chosen such that these numbers are integers. In practice DCT_scaled_size |
| 32 | * values will likely be powers of two, so we actually have the stronger |
| 33 | * condition that DCT_scaled_size / min_DCT_scaled_size is an integer.) |
| 34 | * Upsampling will typically produce max_v_samp_factor pixel rows from each |
| 35 | * row group (times any additional scale factor that the upsampler is |
| 36 | * applying). |
| 37 | * |
| 38 | * The coefficient controller will deliver data to us one iMCU row at a time; |
| 39 | * each iMCU row contains v_samp_factor * DCT_scaled_size sample rows, or |
| 40 | * exactly min_DCT_scaled_size row groups. (This amount of data corresponds |
| 41 | * to one row of MCUs when the image is fully interleaved.) Note that the |
| 42 | * number of sample rows varies across components, but the number of row |
| 43 | * groups does not. Some garbage sample rows may be included in the last iMCU |
| 44 | * row at the bottom of the image. |
| 45 | * |
| 46 | * Depending on the vertical scaling algorithm used, the upsampler may need |
| 47 | * access to the sample row(s) above and below its current input row group. |
| 48 | * The upsampler is required to set need_context_rows TRUE at global selection |
| 49 | * time if so. When need_context_rows is FALSE, this controller can simply |
| 50 | * obtain one iMCU row at a time from the coefficient controller and dole it |
| 51 | * out as row groups to the postprocessor. |
| 52 | * |
| 53 | * When need_context_rows is TRUE, this controller guarantees that the buffer |
| 54 | * passed to postprocessing contains at least one row group's worth of samples |
| 55 | * above and below the row group(s) being processed. Note that the context |
| 56 | * rows "above" the first passed row group appear at negative row offsets in |
| 57 | * the passed buffer. At the top and bottom of the image, the required |
| 58 | * context rows are manufactured by duplicating the first or last real sample |
| 59 | * row; this avoids having special cases in the upsampling inner loops. |
| 60 | * |
| 61 | * The amount of context is fixed at one row group just because that's a |
| 62 | * convenient number for this controller to work with. The existing |
| 63 | * upsamplers really only need one sample row of context. An upsampler |
| 64 | * supporting arbitrary output rescaling might wish for more than one row |
| 65 | * group of context when shrinking the image; tough, we don't handle that. |
| 66 | * (This is justified by the assumption that downsizing will be handled mostly |
| 67 | * by adjusting the DCT_scaled_size values, so that the actual scale factor at |
| 68 | * the upsample step needn't be much less than one.) |
| 69 | * |
| 70 | * To provide the desired context, we have to retain the last two row groups |
| 71 | * of one iMCU row while reading in the next iMCU row. (The last row group |
| 72 | * can't be processed until we have another row group for its below-context, |
| 73 | * and so we have to save the next-to-last group too for its above-context.) |
| 74 | * We could do this most simply by copying data around in our buffer, but |
| 75 | * that'd be very slow. We can avoid copying any data by creating a rather |
| 76 | * strange pointer structure. Here's how it works. We allocate a workspace |
| 77 | * consisting of M+2 row groups (where M = min_DCT_scaled_size is the number |
| 78 | * of row groups per iMCU row). We create two sets of redundant pointers to |
| 79 | * the workspace. Labeling the physical row groups 0 to M+1, the synthesized |
| 80 | * pointer lists look like this: |
| 81 | * M+1 M-1 |
| 82 | * master pointer --> 0 master pointer --> 0 |
| 83 | * 1 1 |
| 84 | * ... ... |
| 85 | * M-3 M-3 |
| 86 | * M-2 M |
| 87 | * M-1 M+1 |
| 88 | * M M-2 |
| 89 | * M+1 M-1 |
| 90 | * 0 0 |
| 91 | * We read alternate iMCU rows using each master pointer; thus the last two |
| 92 | * row groups of the previous iMCU row remain un-overwritten in the workspace. |
| 93 | * The pointer lists are set up so that the required context rows appear to |
| 94 | * be adjacent to the proper places when we pass the pointer lists to the |
| 95 | * upsampler. |
| 96 | * |
| 97 | * The above pictures describe the normal state of the pointer lists. |
| 98 | * At top and bottom of the image, we diddle the pointer lists to duplicate |
| 99 | * the first or last sample row as necessary (this is cheaper than copying |
| 100 | * sample rows around). |
| 101 | * |
| 102 | * This scheme breaks down if M < 2, ie, min_DCT_scaled_size is 1. In that |
| 103 | * situation each iMCU row provides only one row group so the buffering logic |
| 104 | * must be different (eg, we must read two iMCU rows before we can emit the |
| 105 | * first row group). For now, we simply do not support providing context |
| 106 | * rows when min_DCT_scaled_size is 1. That combination seems unlikely to |
| 107 | * be worth providing --- if someone wants a 1/8th-size preview, they probably |
| 108 | * want it quick and dirty, so a context-free upsampler is sufficient. |
| 109 | */ |
| 110 | |
| 111 | |
| 112 | /* Private buffer controller object */ |
| 113 | |
| 114 | typedef struct { |
| 115 | struct jpeg_d_main_controller pub; /* public fields */ |
| 116 | |
| 117 | /* Pointer to allocated workspace (M or M+2 row groups). */ |
| 118 | JSAMPARRAY buffer[MAX_COMPONENTS]; |
| 119 | |
| 120 | boolean buffer_full; /* Have we gotten an iMCU row from decoder? */ |
| 121 | JDIMENSION rowgroup_ctr; /* counts row groups output to postprocessor */ |
| 122 | |
| 123 | /* Remaining fields are only used in the context case. */ |
| 124 | |
| 125 | /* These are the master pointers to the funny-order pointer lists. */ |
| 126 | JSAMPIMAGE xbuffer[2]; /* pointers to weird pointer lists */ |
| 127 | |
| 128 | int whichptr; /* indicates which pointer set is now in use */ |
| 129 | int context_state; /* process_data state machine status */ |
| 130 | JDIMENSION rowgroups_avail; /* row groups available to postprocessor */ |
| 131 | JDIMENSION iMCU_row_ctr; /* counts iMCU rows to detect image top/bot */ |
| 132 | } my_main_controller; |
| 133 | |
| 134 | typedef my_main_controller * my_main_ptr; |
| 135 | |
| 136 | /* context_state values: */ |
| 137 | #define CTX_PREPARE_FOR_IMCU 0 /* need to prepare for MCU row */ |
| 138 | #define CTX_PROCESS_IMCU 1 /* feeding iMCU to postprocessor */ |
| 139 | #define CTX_POSTPONED_ROW 2 /* feeding postponed row group */ |
| 140 | |
| 141 | |
| 142 | /* Forward declarations */ |
| 143 | METHODDEF(void) process_data_simple_main |
| 144 | JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf, |
| 145 | JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)); |
| 146 | METHODDEF(void) process_data_context_main |
| 147 | JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf, |
| 148 | JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)); |
| 149 | #ifdef QUANT_2PASS_SUPPORTED |
| 150 | METHODDEF(void) process_data_crank_post |
| 151 | JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf, |
| 152 | JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)); |
| 153 | #endif |
| 154 | |
| 155 | |
| 156 | LOCAL(void) |
| 157 | alloc_funny_pointers (j_decompress_ptr cinfo) |
| 158 | /* Allocate space for the funny pointer lists. |
| 159 | * This is done only once, not once per pass. |
| 160 | */ |
| 161 | { |
| 162 | my_main_ptr main = (my_main_ptr) cinfo->main; |
| 163 | int ci, rgroup; |
| 164 | int M = cinfo->min_DCT_scaled_size; |
| 165 | jpeg_component_info *compptr; |
| 166 | JSAMPARRAY xbuf; |
| 167 | |
| 168 | /* Get top-level space for component array pointers. |
| 169 | * We alloc both arrays with one call to save a few cycles. |
| 170 | */ |
| 171 | main->xbuffer[0] = (JSAMPIMAGE) |
| 172 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 173 | cinfo->num_components * 2 * SIZEOF(JSAMPARRAY)); |
| 174 | main->xbuffer[1] = main->xbuffer[0] + cinfo->num_components; |
| 175 | |
| 176 | for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
| 177 | ci++, compptr++) { |
| 178 | rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) / |
| 179 | cinfo->min_DCT_scaled_size; /* height of a row group of component */ |
| 180 | /* Get space for pointer lists --- M+4 row groups in each list. |
| 181 | * We alloc both pointer lists with one call to save a few cycles. |
| 182 | */ |
| 183 | xbuf = (JSAMPARRAY) |
| 184 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 185 | 2 * (rgroup * (M + 4)) * SIZEOF(JSAMPROW)); |
| 186 | xbuf += rgroup; /* want one row group at negative offsets */ |
| 187 | main->xbuffer[0][ci] = xbuf; |
| 188 | xbuf += rgroup * (M + 4); |
| 189 | main->xbuffer[1][ci] = xbuf; |
| 190 | } |
| 191 | } |
| 192 | |
| 193 | |
| 194 | LOCAL(void) |
| 195 | make_funny_pointers (j_decompress_ptr cinfo) |
| 196 | /* Create the funny pointer lists discussed in the comments above. |
| 197 | * The actual workspace is already allocated (in main->buffer), |
| 198 | * and the space for the pointer lists is allocated too. |
| 199 | * This routine just fills in the curiously ordered lists. |
| 200 | * This will be repeated at the beginning of each pass. |
| 201 | */ |
| 202 | { |
| 203 | my_main_ptr main = (my_main_ptr) cinfo->main; |
| 204 | int ci, i, rgroup; |
| 205 | int M = cinfo->min_DCT_scaled_size; |
| 206 | jpeg_component_info *compptr; |
| 207 | JSAMPARRAY buf, xbuf0, xbuf1; |
| 208 | |
| 209 | for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
| 210 | ci++, compptr++) { |
| 211 | rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) / |
| 212 | cinfo->min_DCT_scaled_size; /* height of a row group of component */ |
| 213 | xbuf0 = main->xbuffer[0][ci]; |
| 214 | xbuf1 = main->xbuffer[1][ci]; |
| 215 | /* First copy the workspace pointers as-is */ |
| 216 | buf = main->buffer[ci]; |
| 217 | for (i = 0; i < rgroup * (M + 2); i++) { |
| 218 | xbuf0[i] = xbuf1[i] = buf[i]; |
| 219 | } |
| 220 | /* In the second list, put the last four row groups in swapped order */ |
| 221 | for (i = 0; i < rgroup * 2; i++) { |
| 222 | xbuf1[rgroup*(M-2) + i] = buf[rgroup*M + i]; |
| 223 | xbuf1[rgroup*M + i] = buf[rgroup*(M-2) + i]; |
| 224 | } |
| 225 | /* The wraparound pointers at top and bottom will be filled later |
| 226 | * (see set_wraparound_pointers, below). Initially we want the "above" |
| 227 | * pointers to duplicate the first actual data line. This only needs |
| 228 | * to happen in xbuffer[0]. |
| 229 | */ |
| 230 | for (i = 0; i < rgroup; i++) { |
| 231 | xbuf0[i - rgroup] = xbuf0[0]; |
| 232 | } |
| 233 | } |
| 234 | } |
| 235 | |
| 236 | |
| 237 | LOCAL(void) |
| 238 | set_wraparound_pointers (j_decompress_ptr cinfo) |
| 239 | /* Set up the "wraparound" pointers at top and bottom of the pointer lists. |
| 240 | * This changes the pointer list state from top-of-image to the normal state. |
| 241 | */ |
| 242 | { |
| 243 | my_main_ptr main = (my_main_ptr) cinfo->main; |
| 244 | int ci, i, rgroup; |
| 245 | int M = cinfo->min_DCT_scaled_size; |
| 246 | jpeg_component_info *compptr; |
| 247 | JSAMPARRAY xbuf0, xbuf1; |
| 248 | |
| 249 | for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
| 250 | ci++, compptr++) { |
| 251 | rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) / |
| 252 | cinfo->min_DCT_scaled_size; /* height of a row group of component */ |
| 253 | xbuf0 = main->xbuffer[0][ci]; |
| 254 | xbuf1 = main->xbuffer[1][ci]; |
| 255 | for (i = 0; i < rgroup; i++) { |
| 256 | xbuf0[i - rgroup] = xbuf0[rgroup*(M+1) + i]; |
| 257 | xbuf1[i - rgroup] = xbuf1[rgroup*(M+1) + i]; |
| 258 | xbuf0[rgroup*(M+2) + i] = xbuf0[i]; |
| 259 | xbuf1[rgroup*(M+2) + i] = xbuf1[i]; |
| 260 | } |
| 261 | } |
| 262 | } |
| 263 | |
| 264 | |
| 265 | LOCAL(void) |
| 266 | set_bottom_pointers (j_decompress_ptr cinfo) |
| 267 | /* Change the pointer lists to duplicate the last sample row at the bottom |
| 268 | * of the image. whichptr indicates which xbuffer holds the final iMCU row. |
| 269 | * Also sets rowgroups_avail to indicate number of nondummy row groups in row. |
| 270 | */ |
| 271 | { |
| 272 | my_main_ptr main = (my_main_ptr) cinfo->main; |
| 273 | int ci, i, rgroup, iMCUheight, rows_left; |
| 274 | jpeg_component_info *compptr; |
| 275 | JSAMPARRAY xbuf; |
| 276 | |
| 277 | for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
| 278 | ci++, compptr++) { |
| 279 | /* Count sample rows in one iMCU row and in one row group */ |
| 280 | iMCUheight = compptr->v_samp_factor * compptr->DCT_scaled_size; |
| 281 | rgroup = iMCUheight / cinfo->min_DCT_scaled_size; |
| 282 | /* Count nondummy sample rows remaining for this component */ |
| 283 | rows_left = (int) (compptr->downsampled_height % (JDIMENSION) iMCUheight); |
| 284 | if (rows_left == 0) rows_left = iMCUheight; |
| 285 | /* Count nondummy row groups. Should get same answer for each component, |
| 286 | * so we need only do it once. |
| 287 | */ |
| 288 | if (ci == 0) { |
| 289 | main->rowgroups_avail = (JDIMENSION) ((rows_left-1) / rgroup + 1); |
| 290 | } |
| 291 | /* Duplicate the last real sample row rgroup*2 times; this pads out the |
| 292 | * last partial rowgroup and ensures at least one full rowgroup of context. |
| 293 | */ |
| 294 | xbuf = main->xbuffer[main->whichptr][ci]; |
| 295 | for (i = 0; i < rgroup * 2; i++) { |
| 296 | xbuf[rows_left + i] = xbuf[rows_left-1]; |
| 297 | } |
| 298 | } |
| 299 | } |
| 300 | |
| 301 | |
| 302 | /* |
| 303 | * Initialize for a processing pass. |
| 304 | */ |
| 305 | |
| 306 | METHODDEF(void) |
| 307 | start_pass_main (j_decompress_ptr cinfo, J_BUF_MODE pass_mode) |
| 308 | { |
| 309 | my_main_ptr main = (my_main_ptr) cinfo->main; |
| 310 | |
| 311 | switch (pass_mode) { |
| 312 | case JBUF_PASS_THRU: |
| 313 | if (cinfo->upsample->need_context_rows) { |
| 314 | main->pub.process_data = process_data_context_main; |
| 315 | make_funny_pointers(cinfo); /* Create the xbuffer[] lists */ |
| 316 | main->whichptr = 0; /* Read first iMCU row into xbuffer[0] */ |
| 317 | main->context_state = CTX_PREPARE_FOR_IMCU; |
| 318 | main->iMCU_row_ctr = 0; |
| 319 | } else { |
| 320 | /* Simple case with no context needed */ |
| 321 | main->pub.process_data = process_data_simple_main; |
| 322 | } |
| 323 | main->buffer_full = FALSE; /* Mark buffer empty */ |
| 324 | main->rowgroup_ctr = 0; |
| 325 | break; |
| 326 | #ifdef QUANT_2PASS_SUPPORTED |
| 327 | case JBUF_CRANK_DEST: |
| 328 | /* For last pass of 2-pass quantization, just crank the postprocessor */ |
| 329 | main->pub.process_data = process_data_crank_post; |
| 330 | break; |
| 331 | #endif |
| 332 | default: |
| 333 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| 334 | break; |
| 335 | } |
| 336 | } |
| 337 | |
| 338 | |
| 339 | /* |
| 340 | * Process some data. |
| 341 | * This handles the simple case where no context is required. |
| 342 | */ |
| 343 | |
| 344 | METHODDEF(void) |
| 345 | process_data_simple_main (j_decompress_ptr cinfo, |
| 346 | JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, |
| 347 | JDIMENSION out_rows_avail) |
| 348 | { |
| 349 | my_main_ptr main = (my_main_ptr) cinfo->main; |
| 350 | JDIMENSION rowgroups_avail; |
| 351 | |
| 352 | /* Read input data if we haven't filled the main buffer yet */ |
| 353 | if (! main->buffer_full) { |
| 354 | if (! (*cinfo->coef->decompress_data) (cinfo, main->buffer)) |
| 355 | return; /* suspension forced, can do nothing more */ |
| 356 | main->buffer_full = TRUE; /* OK, we have an iMCU row to work with */ |
| 357 | } |
| 358 | |
| 359 | /* There are always min_DCT_scaled_size row groups in an iMCU row. */ |
| 360 | rowgroups_avail = (JDIMENSION) cinfo->min_DCT_scaled_size; |
| 361 | /* Note: at the bottom of the image, we may pass extra garbage row groups |
| 362 | * to the postprocessor. The postprocessor has to check for bottom |
| 363 | * of image anyway (at row resolution), so no point in us doing it too. |
| 364 | */ |
| 365 | |
| 366 | /* Feed the postprocessor */ |
| 367 | (*cinfo->post->post_process_data) (cinfo, main->buffer, |
| 368 | &main->rowgroup_ctr, rowgroups_avail, |
| 369 | output_buf, out_row_ctr, out_rows_avail); |
| 370 | |
| 371 | /* Has postprocessor consumed all the data yet? If so, mark buffer empty */ |
| 372 | if (main->rowgroup_ctr >= rowgroups_avail) { |
| 373 | main->buffer_full = FALSE; |
| 374 | main->rowgroup_ctr = 0; |
| 375 | } |
| 376 | } |
| 377 | |
| 378 | |
| 379 | /* |
| 380 | * Process some data. |
| 381 | * This handles the case where context rows must be provided. |
| 382 | */ |
| 383 | |
| 384 | METHODDEF(void) |
| 385 | process_data_context_main (j_decompress_ptr cinfo, |
| 386 | JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, |
| 387 | JDIMENSION out_rows_avail) |
| 388 | { |
| 389 | my_main_ptr main = (my_main_ptr) cinfo->main; |
| 390 | |
| 391 | /* Read input data if we haven't filled the main buffer yet */ |
| 392 | if (! main->buffer_full) { |
| 393 | if (! (*cinfo->coef->decompress_data) (cinfo, |
| 394 | main->xbuffer[main->whichptr])) |
| 395 | return; /* suspension forced, can do nothing more */ |
| 396 | main->buffer_full = TRUE; /* OK, we have an iMCU row to work with */ |
| 397 | main->iMCU_row_ctr++; /* count rows received */ |
| 398 | } |
| 399 | |
| 400 | /* Postprocessor typically will not swallow all the input data it is handed |
| 401 | * in one call (due to filling the output buffer first). Must be prepared |
| 402 | * to exit and restart. This switch lets us keep track of how far we got. |
| 403 | * Note that each case falls through to the next on successful completion. |
| 404 | */ |
| 405 | switch (main->context_state) { |
| 406 | case CTX_POSTPONED_ROW: |
| 407 | /* Call postprocessor using previously set pointers for postponed row */ |
| 408 | (*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr], |
| 409 | &main->rowgroup_ctr, main->rowgroups_avail, |
| 410 | output_buf, out_row_ctr, out_rows_avail); |
| 411 | if (main->rowgroup_ctr < main->rowgroups_avail) |
| 412 | return; /* Need to suspend */ |
| 413 | main->context_state = CTX_PREPARE_FOR_IMCU; |
| 414 | if (*out_row_ctr >= out_rows_avail) |
| 415 | return; /* Postprocessor exactly filled output buf */ |
| 416 | /*FALLTHROUGH*/ |
| 417 | case CTX_PREPARE_FOR_IMCU: |
| 418 | /* Prepare to process first M-1 row groups of this iMCU row */ |
| 419 | main->rowgroup_ctr = 0; |
| 420 | main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_scaled_size - 1); |
| 421 | /* Check for bottom of image: if so, tweak pointers to "duplicate" |
| 422 | * the last sample row, and adjust rowgroups_avail to ignore padding rows. |
| 423 | */ |
| 424 | if (main->iMCU_row_ctr == cinfo->total_iMCU_rows) |
| 425 | set_bottom_pointers(cinfo); |
| 426 | main->context_state = CTX_PROCESS_IMCU; |
| 427 | /*FALLTHROUGH*/ |
| 428 | case CTX_PROCESS_IMCU: |
| 429 | /* Call postprocessor using previously set pointers */ |
| 430 | (*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr], |
| 431 | &main->rowgroup_ctr, main->rowgroups_avail, |
| 432 | output_buf, out_row_ctr, out_rows_avail); |
| 433 | if (main->rowgroup_ctr < main->rowgroups_avail) |
| 434 | return; /* Need to suspend */ |
| 435 | /* After the first iMCU, change wraparound pointers to normal state */ |
| 436 | if (main->iMCU_row_ctr == 1) |
| 437 | set_wraparound_pointers(cinfo); |
| 438 | /* Prepare to load new iMCU row using other xbuffer list */ |
| 439 | main->whichptr ^= 1; /* 0=>1 or 1=>0 */ |
| 440 | main->buffer_full = FALSE; |
| 441 | /* Still need to process last row group of this iMCU row, */ |
| 442 | /* which is saved at index M+1 of the other xbuffer */ |
| 443 | main->rowgroup_ctr = (JDIMENSION) (cinfo->min_DCT_scaled_size + 1); |
| 444 | main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_scaled_size + 2); |
| 445 | main->context_state = CTX_POSTPONED_ROW; |
| 446 | } |
| 447 | } |
| 448 | |
| 449 | |
| 450 | /* |
| 451 | * Process some data. |
| 452 | * Final pass of two-pass quantization: just call the postprocessor. |
| 453 | * Source data will be the postprocessor controller's internal buffer. |
| 454 | */ |
| 455 | |
| 456 | #ifdef QUANT_2PASS_SUPPORTED |
| 457 | |
| 458 | METHODDEF(void) |
| 459 | process_data_crank_post (j_decompress_ptr cinfo, |
| 460 | JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, |
| 461 | JDIMENSION out_rows_avail) |
| 462 | { |
| 463 | (*cinfo->post->post_process_data) (cinfo, (JSAMPIMAGE) NULL, |
| 464 | (JDIMENSION *) NULL, (JDIMENSION) 0, |
| 465 | output_buf, out_row_ctr, out_rows_avail); |
| 466 | } |
| 467 | |
| 468 | #endif /* QUANT_2PASS_SUPPORTED */ |
| 469 | |
| 470 | |
| 471 | /* |
| 472 | * Initialize main buffer controller. |
| 473 | */ |
| 474 | |
| 475 | GLOBAL(void) |
| 476 | jinit_d_main_controller (j_decompress_ptr cinfo, boolean need_full_buffer) |
| 477 | { |
| 478 | my_main_ptr main; |
| 479 | int ci, rgroup, ngroups; |
| 480 | jpeg_component_info *compptr; |
| 481 | |
| 482 | main = (my_main_ptr) |
| 483 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 484 | SIZEOF(my_main_controller)); |
| 485 | cinfo->main = (struct jpeg_d_main_controller *) main; |
| 486 | main->pub.start_pass = start_pass_main; |
| 487 | |
| 488 | if (need_full_buffer) /* shouldn't happen */ |
| 489 | ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); |
| 490 | |
| 491 | /* Allocate the workspace. |
| 492 | * ngroups is the number of row groups we need. |
| 493 | */ |
| 494 | if (cinfo->upsample->need_context_rows) { |
| 495 | if (cinfo->min_DCT_scaled_size < 2) /* unsupported, see comments above */ |
| 496 | ERREXIT(cinfo, JERR_NOTIMPL); |
| 497 | alloc_funny_pointers(cinfo); /* Alloc space for xbuffer[] lists */ |
| 498 | ngroups = cinfo->min_DCT_scaled_size + 2; |
| 499 | } else { |
| 500 | ngroups = cinfo->min_DCT_scaled_size; |
| 501 | } |
| 502 | |
| 503 | for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
| 504 | ci++, compptr++) { |
| 505 | rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) / |
| 506 | cinfo->min_DCT_scaled_size; /* height of a row group of component */ |
| 507 | main->buffer[ci] = (*cinfo->mem->alloc_sarray) |
| 508 | ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 509 | compptr->width_in_blocks * compptr->DCT_scaled_size, |
| 510 | (JDIMENSION) (rgroup * ngroups)); |
| 511 | } |
| 512 | } |