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annotate libs/libjpeg/jdmainct.c @ 2:334d17aed7de

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author John Tsiombikas <nuclear@member.fsf.org>
date Sun, 02 Feb 2014 18:36:38 +0200
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nuclear@0 1 /*
nuclear@0 2 * jdmainct.c
nuclear@0 3 *
nuclear@0 4 * Copyright (C) 1994-1996, Thomas G. Lane.
nuclear@0 5 * This file is part of the Independent JPEG Group's software.
nuclear@0 6 * For conditions of distribution and use, see the accompanying README file.
nuclear@0 7 *
nuclear@0 8 * This file contains the main buffer controller for decompression.
nuclear@0 9 * The main buffer lies between the JPEG decompressor proper and the
nuclear@0 10 * post-processor; it holds downsampled data in the JPEG colorspace.
nuclear@0 11 *
nuclear@0 12 * Note that this code is bypassed in raw-data mode, since the application
nuclear@0 13 * supplies the equivalent of the main buffer in that case.
nuclear@0 14 */
nuclear@0 15
nuclear@0 16 #define JPEG_INTERNALS
nuclear@0 17 #include "jinclude.h"
nuclear@0 18 #include "jpeglib.h"
nuclear@0 19
nuclear@0 20
nuclear@0 21 /*
nuclear@0 22 * In the current system design, the main buffer need never be a full-image
nuclear@0 23 * buffer; any full-height buffers will be found inside the coefficient or
nuclear@0 24 * postprocessing controllers. Nonetheless, the main controller is not
nuclear@0 25 * trivial. Its responsibility is to provide context rows for upsampling/
nuclear@0 26 * rescaling, and doing this in an efficient fashion is a bit tricky.
nuclear@0 27 *
nuclear@0 28 * Postprocessor input data is counted in "row groups". A row group
nuclear@0 29 * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
nuclear@0 30 * sample rows of each component. (We require DCT_scaled_size values to be
nuclear@0 31 * chosen such that these numbers are integers. In practice DCT_scaled_size
nuclear@0 32 * values will likely be powers of two, so we actually have the stronger
nuclear@0 33 * condition that DCT_scaled_size / min_DCT_scaled_size is an integer.)
nuclear@0 34 * Upsampling will typically produce max_v_samp_factor pixel rows from each
nuclear@0 35 * row group (times any additional scale factor that the upsampler is
nuclear@0 36 * applying).
nuclear@0 37 *
nuclear@0 38 * The coefficient controller will deliver data to us one iMCU row at a time;
nuclear@0 39 * each iMCU row contains v_samp_factor * DCT_scaled_size sample rows, or
nuclear@0 40 * exactly min_DCT_scaled_size row groups. (This amount of data corresponds
nuclear@0 41 * to one row of MCUs when the image is fully interleaved.) Note that the
nuclear@0 42 * number of sample rows varies across components, but the number of row
nuclear@0 43 * groups does not. Some garbage sample rows may be included in the last iMCU
nuclear@0 44 * row at the bottom of the image.
nuclear@0 45 *
nuclear@0 46 * Depending on the vertical scaling algorithm used, the upsampler may need
nuclear@0 47 * access to the sample row(s) above and below its current input row group.
nuclear@0 48 * The upsampler is required to set need_context_rows TRUE at global selection
nuclear@0 49 * time if so. When need_context_rows is FALSE, this controller can simply
nuclear@0 50 * obtain one iMCU row at a time from the coefficient controller and dole it
nuclear@0 51 * out as row groups to the postprocessor.
nuclear@0 52 *
nuclear@0 53 * When need_context_rows is TRUE, this controller guarantees that the buffer
nuclear@0 54 * passed to postprocessing contains at least one row group's worth of samples
nuclear@0 55 * above and below the row group(s) being processed. Note that the context
nuclear@0 56 * rows "above" the first passed row group appear at negative row offsets in
nuclear@0 57 * the passed buffer. At the top and bottom of the image, the required
nuclear@0 58 * context rows are manufactured by duplicating the first or last real sample
nuclear@0 59 * row; this avoids having special cases in the upsampling inner loops.
nuclear@0 60 *
nuclear@0 61 * The amount of context is fixed at one row group just because that's a
nuclear@0 62 * convenient number for this controller to work with. The existing
nuclear@0 63 * upsamplers really only need one sample row of context. An upsampler
nuclear@0 64 * supporting arbitrary output rescaling might wish for more than one row
nuclear@0 65 * group of context when shrinking the image; tough, we don't handle that.
nuclear@0 66 * (This is justified by the assumption that downsizing will be handled mostly
nuclear@0 67 * by adjusting the DCT_scaled_size values, so that the actual scale factor at
nuclear@0 68 * the upsample step needn't be much less than one.)
nuclear@0 69 *
nuclear@0 70 * To provide the desired context, we have to retain the last two row groups
nuclear@0 71 * of one iMCU row while reading in the next iMCU row. (The last row group
nuclear@0 72 * can't be processed until we have another row group for its below-context,
nuclear@0 73 * and so we have to save the next-to-last group too for its above-context.)
nuclear@0 74 * We could do this most simply by copying data around in our buffer, but
nuclear@0 75 * that'd be very slow. We can avoid copying any data by creating a rather
nuclear@0 76 * strange pointer structure. Here's how it works. We allocate a workspace
nuclear@0 77 * consisting of M+2 row groups (where M = min_DCT_scaled_size is the number
nuclear@0 78 * of row groups per iMCU row). We create two sets of redundant pointers to
nuclear@0 79 * the workspace. Labeling the physical row groups 0 to M+1, the synthesized
nuclear@0 80 * pointer lists look like this:
nuclear@0 81 * M+1 M-1
nuclear@0 82 * master pointer --> 0 master pointer --> 0
nuclear@0 83 * 1 1
nuclear@0 84 * ... ...
nuclear@0 85 * M-3 M-3
nuclear@0 86 * M-2 M
nuclear@0 87 * M-1 M+1
nuclear@0 88 * M M-2
nuclear@0 89 * M+1 M-1
nuclear@0 90 * 0 0
nuclear@0 91 * We read alternate iMCU rows using each master pointer; thus the last two
nuclear@0 92 * row groups of the previous iMCU row remain un-overwritten in the workspace.
nuclear@0 93 * The pointer lists are set up so that the required context rows appear to
nuclear@0 94 * be adjacent to the proper places when we pass the pointer lists to the
nuclear@0 95 * upsampler.
nuclear@0 96 *
nuclear@0 97 * The above pictures describe the normal state of the pointer lists.
nuclear@0 98 * At top and bottom of the image, we diddle the pointer lists to duplicate
nuclear@0 99 * the first or last sample row as necessary (this is cheaper than copying
nuclear@0 100 * sample rows around).
nuclear@0 101 *
nuclear@0 102 * This scheme breaks down if M < 2, ie, min_DCT_scaled_size is 1. In that
nuclear@0 103 * situation each iMCU row provides only one row group so the buffering logic
nuclear@0 104 * must be different (eg, we must read two iMCU rows before we can emit the
nuclear@0 105 * first row group). For now, we simply do not support providing context
nuclear@0 106 * rows when min_DCT_scaled_size is 1. That combination seems unlikely to
nuclear@0 107 * be worth providing --- if someone wants a 1/8th-size preview, they probably
nuclear@0 108 * want it quick and dirty, so a context-free upsampler is sufficient.
nuclear@0 109 */
nuclear@0 110
nuclear@0 111
nuclear@0 112 /* Private buffer controller object */
nuclear@0 113
nuclear@0 114 typedef struct {
nuclear@0 115 struct jpeg_d_main_controller pub; /* public fields */
nuclear@0 116
nuclear@0 117 /* Pointer to allocated workspace (M or M+2 row groups). */
nuclear@0 118 JSAMPARRAY buffer[MAX_COMPONENTS];
nuclear@0 119
nuclear@0 120 boolean buffer_full; /* Have we gotten an iMCU row from decoder? */
nuclear@0 121 JDIMENSION rowgroup_ctr; /* counts row groups output to postprocessor */
nuclear@0 122
nuclear@0 123 /* Remaining fields are only used in the context case. */
nuclear@0 124
nuclear@0 125 /* These are the master pointers to the funny-order pointer lists. */
nuclear@0 126 JSAMPIMAGE xbuffer[2]; /* pointers to weird pointer lists */
nuclear@0 127
nuclear@0 128 int whichptr; /* indicates which pointer set is now in use */
nuclear@0 129 int context_state; /* process_data state machine status */
nuclear@0 130 JDIMENSION rowgroups_avail; /* row groups available to postprocessor */
nuclear@0 131 JDIMENSION iMCU_row_ctr; /* counts iMCU rows to detect image top/bot */
nuclear@0 132 } my_main_controller;
nuclear@0 133
nuclear@0 134 typedef my_main_controller * my_main_ptr;
nuclear@0 135
nuclear@0 136 /* context_state values: */
nuclear@0 137 #define CTX_PREPARE_FOR_IMCU 0 /* need to prepare for MCU row */
nuclear@0 138 #define CTX_PROCESS_IMCU 1 /* feeding iMCU to postprocessor */
nuclear@0 139 #define CTX_POSTPONED_ROW 2 /* feeding postponed row group */
nuclear@0 140
nuclear@0 141
nuclear@0 142 /* Forward declarations */
nuclear@0 143 METHODDEF(void) process_data_simple_main
nuclear@0 144 JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf,
nuclear@0 145 JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail));
nuclear@0 146 METHODDEF(void) process_data_context_main
nuclear@0 147 JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf,
nuclear@0 148 JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail));
nuclear@0 149 #ifdef QUANT_2PASS_SUPPORTED
nuclear@0 150 METHODDEF(void) process_data_crank_post
nuclear@0 151 JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf,
nuclear@0 152 JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail));
nuclear@0 153 #endif
nuclear@0 154
nuclear@0 155
nuclear@0 156 LOCAL(void)
nuclear@0 157 alloc_funny_pointers (j_decompress_ptr cinfo)
nuclear@0 158 /* Allocate space for the funny pointer lists.
nuclear@0 159 * This is done only once, not once per pass.
nuclear@0 160 */
nuclear@0 161 {
nuclear@0 162 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@0 163 int ci, rgroup;
nuclear@0 164 int M = cinfo->min_DCT_scaled_size;
nuclear@0 165 jpeg_component_info *compptr;
nuclear@0 166 JSAMPARRAY xbuf;
nuclear@0 167
nuclear@0 168 /* Get top-level space for component array pointers.
nuclear@0 169 * We alloc both arrays with one call to save a few cycles.
nuclear@0 170 */
nuclear@0 171 main->xbuffer[0] = (JSAMPIMAGE)
nuclear@0 172 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@0 173 cinfo->num_components * 2 * SIZEOF(JSAMPARRAY));
nuclear@0 174 main->xbuffer[1] = main->xbuffer[0] + cinfo->num_components;
nuclear@0 175
nuclear@0 176 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@0 177 ci++, compptr++) {
nuclear@0 178 rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@0 179 cinfo->min_DCT_scaled_size; /* height of a row group of component */
nuclear@0 180 /* Get space for pointer lists --- M+4 row groups in each list.
nuclear@0 181 * We alloc both pointer lists with one call to save a few cycles.
nuclear@0 182 */
nuclear@0 183 xbuf = (JSAMPARRAY)
nuclear@0 184 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@0 185 2 * (rgroup * (M + 4)) * SIZEOF(JSAMPROW));
nuclear@0 186 xbuf += rgroup; /* want one row group at negative offsets */
nuclear@0 187 main->xbuffer[0][ci] = xbuf;
nuclear@0 188 xbuf += rgroup * (M + 4);
nuclear@0 189 main->xbuffer[1][ci] = xbuf;
nuclear@0 190 }
nuclear@0 191 }
nuclear@0 192
nuclear@0 193
nuclear@0 194 LOCAL(void)
nuclear@0 195 make_funny_pointers (j_decompress_ptr cinfo)
nuclear@0 196 /* Create the funny pointer lists discussed in the comments above.
nuclear@0 197 * The actual workspace is already allocated (in main->buffer),
nuclear@0 198 * and the space for the pointer lists is allocated too.
nuclear@0 199 * This routine just fills in the curiously ordered lists.
nuclear@0 200 * This will be repeated at the beginning of each pass.
nuclear@0 201 */
nuclear@0 202 {
nuclear@0 203 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@0 204 int ci, i, rgroup;
nuclear@0 205 int M = cinfo->min_DCT_scaled_size;
nuclear@0 206 jpeg_component_info *compptr;
nuclear@0 207 JSAMPARRAY buf, xbuf0, xbuf1;
nuclear@0 208
nuclear@0 209 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@0 210 ci++, compptr++) {
nuclear@0 211 rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@0 212 cinfo->min_DCT_scaled_size; /* height of a row group of component */
nuclear@0 213 xbuf0 = main->xbuffer[0][ci];
nuclear@0 214 xbuf1 = main->xbuffer[1][ci];
nuclear@0 215 /* First copy the workspace pointers as-is */
nuclear@0 216 buf = main->buffer[ci];
nuclear@0 217 for (i = 0; i < rgroup * (M + 2); i++) {
nuclear@0 218 xbuf0[i] = xbuf1[i] = buf[i];
nuclear@0 219 }
nuclear@0 220 /* In the second list, put the last four row groups in swapped order */
nuclear@0 221 for (i = 0; i < rgroup * 2; i++) {
nuclear@0 222 xbuf1[rgroup*(M-2) + i] = buf[rgroup*M + i];
nuclear@0 223 xbuf1[rgroup*M + i] = buf[rgroup*(M-2) + i];
nuclear@0 224 }
nuclear@0 225 /* The wraparound pointers at top and bottom will be filled later
nuclear@0 226 * (see set_wraparound_pointers, below). Initially we want the "above"
nuclear@0 227 * pointers to duplicate the first actual data line. This only needs
nuclear@0 228 * to happen in xbuffer[0].
nuclear@0 229 */
nuclear@0 230 for (i = 0; i < rgroup; i++) {
nuclear@0 231 xbuf0[i - rgroup] = xbuf0[0];
nuclear@0 232 }
nuclear@0 233 }
nuclear@0 234 }
nuclear@0 235
nuclear@0 236
nuclear@0 237 LOCAL(void)
nuclear@0 238 set_wraparound_pointers (j_decompress_ptr cinfo)
nuclear@0 239 /* Set up the "wraparound" pointers at top and bottom of the pointer lists.
nuclear@0 240 * This changes the pointer list state from top-of-image to the normal state.
nuclear@0 241 */
nuclear@0 242 {
nuclear@0 243 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@0 244 int ci, i, rgroup;
nuclear@0 245 int M = cinfo->min_DCT_scaled_size;
nuclear@0 246 jpeg_component_info *compptr;
nuclear@0 247 JSAMPARRAY xbuf0, xbuf1;
nuclear@0 248
nuclear@0 249 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@0 250 ci++, compptr++) {
nuclear@0 251 rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@0 252 cinfo->min_DCT_scaled_size; /* height of a row group of component */
nuclear@0 253 xbuf0 = main->xbuffer[0][ci];
nuclear@0 254 xbuf1 = main->xbuffer[1][ci];
nuclear@0 255 for (i = 0; i < rgroup; i++) {
nuclear@0 256 xbuf0[i - rgroup] = xbuf0[rgroup*(M+1) + i];
nuclear@0 257 xbuf1[i - rgroup] = xbuf1[rgroup*(M+1) + i];
nuclear@0 258 xbuf0[rgroup*(M+2) + i] = xbuf0[i];
nuclear@0 259 xbuf1[rgroup*(M+2) + i] = xbuf1[i];
nuclear@0 260 }
nuclear@0 261 }
nuclear@0 262 }
nuclear@0 263
nuclear@0 264
nuclear@0 265 LOCAL(void)
nuclear@0 266 set_bottom_pointers (j_decompress_ptr cinfo)
nuclear@0 267 /* Change the pointer lists to duplicate the last sample row at the bottom
nuclear@0 268 * of the image. whichptr indicates which xbuffer holds the final iMCU row.
nuclear@0 269 * Also sets rowgroups_avail to indicate number of nondummy row groups in row.
nuclear@0 270 */
nuclear@0 271 {
nuclear@0 272 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@0 273 int ci, i, rgroup, iMCUheight, rows_left;
nuclear@0 274 jpeg_component_info *compptr;
nuclear@0 275 JSAMPARRAY xbuf;
nuclear@0 276
nuclear@0 277 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@0 278 ci++, compptr++) {
nuclear@0 279 /* Count sample rows in one iMCU row and in one row group */
nuclear@0 280 iMCUheight = compptr->v_samp_factor * compptr->DCT_scaled_size;
nuclear@0 281 rgroup = iMCUheight / cinfo->min_DCT_scaled_size;
nuclear@0 282 /* Count nondummy sample rows remaining for this component */
nuclear@0 283 rows_left = (int) (compptr->downsampled_height % (JDIMENSION) iMCUheight);
nuclear@0 284 if (rows_left == 0) rows_left = iMCUheight;
nuclear@0 285 /* Count nondummy row groups. Should get same answer for each component,
nuclear@0 286 * so we need only do it once.
nuclear@0 287 */
nuclear@0 288 if (ci == 0) {
nuclear@0 289 main->rowgroups_avail = (JDIMENSION) ((rows_left-1) / rgroup + 1);
nuclear@0 290 }
nuclear@0 291 /* Duplicate the last real sample row rgroup*2 times; this pads out the
nuclear@0 292 * last partial rowgroup and ensures at least one full rowgroup of context.
nuclear@0 293 */
nuclear@0 294 xbuf = main->xbuffer[main->whichptr][ci];
nuclear@0 295 for (i = 0; i < rgroup * 2; i++) {
nuclear@0 296 xbuf[rows_left + i] = xbuf[rows_left-1];
nuclear@0 297 }
nuclear@0 298 }
nuclear@0 299 }
nuclear@0 300
nuclear@0 301
nuclear@0 302 /*
nuclear@0 303 * Initialize for a processing pass.
nuclear@0 304 */
nuclear@0 305
nuclear@0 306 METHODDEF(void)
nuclear@0 307 start_pass_main (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
nuclear@0 308 {
nuclear@0 309 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@0 310
nuclear@0 311 switch (pass_mode) {
nuclear@0 312 case JBUF_PASS_THRU:
nuclear@0 313 if (cinfo->upsample->need_context_rows) {
nuclear@0 314 main->pub.process_data = process_data_context_main;
nuclear@0 315 make_funny_pointers(cinfo); /* Create the xbuffer[] lists */
nuclear@0 316 main->whichptr = 0; /* Read first iMCU row into xbuffer[0] */
nuclear@0 317 main->context_state = CTX_PREPARE_FOR_IMCU;
nuclear@0 318 main->iMCU_row_ctr = 0;
nuclear@0 319 } else {
nuclear@0 320 /* Simple case with no context needed */
nuclear@0 321 main->pub.process_data = process_data_simple_main;
nuclear@0 322 }
nuclear@0 323 main->buffer_full = FALSE; /* Mark buffer empty */
nuclear@0 324 main->rowgroup_ctr = 0;
nuclear@0 325 break;
nuclear@0 326 #ifdef QUANT_2PASS_SUPPORTED
nuclear@0 327 case JBUF_CRANK_DEST:
nuclear@0 328 /* For last pass of 2-pass quantization, just crank the postprocessor */
nuclear@0 329 main->pub.process_data = process_data_crank_post;
nuclear@0 330 break;
nuclear@0 331 #endif
nuclear@0 332 default:
nuclear@0 333 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
nuclear@0 334 break;
nuclear@0 335 }
nuclear@0 336 }
nuclear@0 337
nuclear@0 338
nuclear@0 339 /*
nuclear@0 340 * Process some data.
nuclear@0 341 * This handles the simple case where no context is required.
nuclear@0 342 */
nuclear@0 343
nuclear@0 344 METHODDEF(void)
nuclear@0 345 process_data_simple_main (j_decompress_ptr cinfo,
nuclear@0 346 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@0 347 JDIMENSION out_rows_avail)
nuclear@0 348 {
nuclear@0 349 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@0 350 JDIMENSION rowgroups_avail;
nuclear@0 351
nuclear@0 352 /* Read input data if we haven't filled the main buffer yet */
nuclear@0 353 if (! main->buffer_full) {
nuclear@0 354 if (! (*cinfo->coef->decompress_data) (cinfo, main->buffer))
nuclear@0 355 return; /* suspension forced, can do nothing more */
nuclear@0 356 main->buffer_full = TRUE; /* OK, we have an iMCU row to work with */
nuclear@0 357 }
nuclear@0 358
nuclear@0 359 /* There are always min_DCT_scaled_size row groups in an iMCU row. */
nuclear@0 360 rowgroups_avail = (JDIMENSION) cinfo->min_DCT_scaled_size;
nuclear@0 361 /* Note: at the bottom of the image, we may pass extra garbage row groups
nuclear@0 362 * to the postprocessor. The postprocessor has to check for bottom
nuclear@0 363 * of image anyway (at row resolution), so no point in us doing it too.
nuclear@0 364 */
nuclear@0 365
nuclear@0 366 /* Feed the postprocessor */
nuclear@0 367 (*cinfo->post->post_process_data) (cinfo, main->buffer,
nuclear@0 368 &main->rowgroup_ctr, rowgroups_avail,
nuclear@0 369 output_buf, out_row_ctr, out_rows_avail);
nuclear@0 370
nuclear@0 371 /* Has postprocessor consumed all the data yet? If so, mark buffer empty */
nuclear@0 372 if (main->rowgroup_ctr >= rowgroups_avail) {
nuclear@0 373 main->buffer_full = FALSE;
nuclear@0 374 main->rowgroup_ctr = 0;
nuclear@0 375 }
nuclear@0 376 }
nuclear@0 377
nuclear@0 378
nuclear@0 379 /*
nuclear@0 380 * Process some data.
nuclear@0 381 * This handles the case where context rows must be provided.
nuclear@0 382 */
nuclear@0 383
nuclear@0 384 METHODDEF(void)
nuclear@0 385 process_data_context_main (j_decompress_ptr cinfo,
nuclear@0 386 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@0 387 JDIMENSION out_rows_avail)
nuclear@0 388 {
nuclear@0 389 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@0 390
nuclear@0 391 /* Read input data if we haven't filled the main buffer yet */
nuclear@0 392 if (! main->buffer_full) {
nuclear@0 393 if (! (*cinfo->coef->decompress_data) (cinfo,
nuclear@0 394 main->xbuffer[main->whichptr]))
nuclear@0 395 return; /* suspension forced, can do nothing more */
nuclear@0 396 main->buffer_full = TRUE; /* OK, we have an iMCU row to work with */
nuclear@0 397 main->iMCU_row_ctr++; /* count rows received */
nuclear@0 398 }
nuclear@0 399
nuclear@0 400 /* Postprocessor typically will not swallow all the input data it is handed
nuclear@0 401 * in one call (due to filling the output buffer first). Must be prepared
nuclear@0 402 * to exit and restart. This switch lets us keep track of how far we got.
nuclear@0 403 * Note that each case falls through to the next on successful completion.
nuclear@0 404 */
nuclear@0 405 switch (main->context_state) {
nuclear@0 406 case CTX_POSTPONED_ROW:
nuclear@0 407 /* Call postprocessor using previously set pointers for postponed row */
nuclear@0 408 (*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr],
nuclear@0 409 &main->rowgroup_ctr, main->rowgroups_avail,
nuclear@0 410 output_buf, out_row_ctr, out_rows_avail);
nuclear@0 411 if (main->rowgroup_ctr < main->rowgroups_avail)
nuclear@0 412 return; /* Need to suspend */
nuclear@0 413 main->context_state = CTX_PREPARE_FOR_IMCU;
nuclear@0 414 if (*out_row_ctr >= out_rows_avail)
nuclear@0 415 return; /* Postprocessor exactly filled output buf */
nuclear@0 416 /*FALLTHROUGH*/
nuclear@0 417 case CTX_PREPARE_FOR_IMCU:
nuclear@0 418 /* Prepare to process first M-1 row groups of this iMCU row */
nuclear@0 419 main->rowgroup_ctr = 0;
nuclear@0 420 main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_scaled_size - 1);
nuclear@0 421 /* Check for bottom of image: if so, tweak pointers to "duplicate"
nuclear@0 422 * the last sample row, and adjust rowgroups_avail to ignore padding rows.
nuclear@0 423 */
nuclear@0 424 if (main->iMCU_row_ctr == cinfo->total_iMCU_rows)
nuclear@0 425 set_bottom_pointers(cinfo);
nuclear@0 426 main->context_state = CTX_PROCESS_IMCU;
nuclear@0 427 /*FALLTHROUGH*/
nuclear@0 428 case CTX_PROCESS_IMCU:
nuclear@0 429 /* Call postprocessor using previously set pointers */
nuclear@0 430 (*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr],
nuclear@0 431 &main->rowgroup_ctr, main->rowgroups_avail,
nuclear@0 432 output_buf, out_row_ctr, out_rows_avail);
nuclear@0 433 if (main->rowgroup_ctr < main->rowgroups_avail)
nuclear@0 434 return; /* Need to suspend */
nuclear@0 435 /* After the first iMCU, change wraparound pointers to normal state */
nuclear@0 436 if (main->iMCU_row_ctr == 1)
nuclear@0 437 set_wraparound_pointers(cinfo);
nuclear@0 438 /* Prepare to load new iMCU row using other xbuffer list */
nuclear@0 439 main->whichptr ^= 1; /* 0=>1 or 1=>0 */
nuclear@0 440 main->buffer_full = FALSE;
nuclear@0 441 /* Still need to process last row group of this iMCU row, */
nuclear@0 442 /* which is saved at index M+1 of the other xbuffer */
nuclear@0 443 main->rowgroup_ctr = (JDIMENSION) (cinfo->min_DCT_scaled_size + 1);
nuclear@0 444 main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_scaled_size + 2);
nuclear@0 445 main->context_state = CTX_POSTPONED_ROW;
nuclear@0 446 }
nuclear@0 447 }
nuclear@0 448
nuclear@0 449
nuclear@0 450 /*
nuclear@0 451 * Process some data.
nuclear@0 452 * Final pass of two-pass quantization: just call the postprocessor.
nuclear@0 453 * Source data will be the postprocessor controller's internal buffer.
nuclear@0 454 */
nuclear@0 455
nuclear@0 456 #ifdef QUANT_2PASS_SUPPORTED
nuclear@0 457
nuclear@0 458 METHODDEF(void)
nuclear@0 459 process_data_crank_post (j_decompress_ptr cinfo,
nuclear@0 460 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@0 461 JDIMENSION out_rows_avail)
nuclear@0 462 {
nuclear@0 463 (*cinfo->post->post_process_data) (cinfo, (JSAMPIMAGE) NULL,
nuclear@0 464 (JDIMENSION *) NULL, (JDIMENSION) 0,
nuclear@0 465 output_buf, out_row_ctr, out_rows_avail);
nuclear@0 466 }
nuclear@0 467
nuclear@0 468 #endif /* QUANT_2PASS_SUPPORTED */
nuclear@0 469
nuclear@0 470
nuclear@0 471 /*
nuclear@0 472 * Initialize main buffer controller.
nuclear@0 473 */
nuclear@0 474
nuclear@0 475 GLOBAL(void)
nuclear@0 476 jinit_d_main_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
nuclear@0 477 {
nuclear@0 478 my_main_ptr main;
nuclear@0 479 int ci, rgroup, ngroups;
nuclear@0 480 jpeg_component_info *compptr;
nuclear@0 481
nuclear@0 482 main = (my_main_ptr)
nuclear@0 483 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@0 484 SIZEOF(my_main_controller));
nuclear@0 485 cinfo->main = (struct jpeg_d_main_controller *) main;
nuclear@0 486 main->pub.start_pass = start_pass_main;
nuclear@0 487
nuclear@0 488 if (need_full_buffer) /* shouldn't happen */
nuclear@0 489 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
nuclear@0 490
nuclear@0 491 /* Allocate the workspace.
nuclear@0 492 * ngroups is the number of row groups we need.
nuclear@0 493 */
nuclear@0 494 if (cinfo->upsample->need_context_rows) {
nuclear@0 495 if (cinfo->min_DCT_scaled_size < 2) /* unsupported, see comments above */
nuclear@0 496 ERREXIT(cinfo, JERR_NOTIMPL);
nuclear@0 497 alloc_funny_pointers(cinfo); /* Alloc space for xbuffer[] lists */
nuclear@0 498 ngroups = cinfo->min_DCT_scaled_size + 2;
nuclear@0 499 } else {
nuclear@0 500 ngroups = cinfo->min_DCT_scaled_size;
nuclear@0 501 }
nuclear@0 502
nuclear@0 503 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@0 504 ci++, compptr++) {
nuclear@0 505 rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@0 506 cinfo->min_DCT_scaled_size; /* height of a row group of component */
nuclear@0 507 main->buffer[ci] = (*cinfo->mem->alloc_sarray)
nuclear@0 508 ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@0 509 compptr->width_in_blocks * compptr->DCT_scaled_size,
nuclear@0 510 (JDIMENSION) (rgroup * ngroups));
nuclear@0 511 }
nuclear@0 512 }