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annotate libs/libjpeg/jdmainct.c @ 39:ff055bff6a15

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author John Tsiombikas <nuclear@mutantstargoat.com>
date Sun, 11 Sep 2011 09:03:18 +0300
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nuclear@26 1 /*
nuclear@26 2 * jdmainct.c
nuclear@26 3 *
nuclear@26 4 * Copyright (C) 1994-1996, Thomas G. Lane.
nuclear@26 5 * This file is part of the Independent JPEG Group's software.
nuclear@26 6 * For conditions of distribution and use, see the accompanying README file.
nuclear@26 7 *
nuclear@26 8 * This file contains the main buffer controller for decompression.
nuclear@26 9 * The main buffer lies between the JPEG decompressor proper and the
nuclear@26 10 * post-processor; it holds downsampled data in the JPEG colorspace.
nuclear@26 11 *
nuclear@26 12 * Note that this code is bypassed in raw-data mode, since the application
nuclear@26 13 * supplies the equivalent of the main buffer in that case.
nuclear@26 14 */
nuclear@26 15
nuclear@26 16 #define JPEG_INTERNALS
nuclear@26 17 #include "jinclude.h"
nuclear@26 18 #include "jpeglib.h"
nuclear@26 19
nuclear@26 20
nuclear@26 21 /*
nuclear@26 22 * In the current system design, the main buffer need never be a full-image
nuclear@26 23 * buffer; any full-height buffers will be found inside the coefficient or
nuclear@26 24 * postprocessing controllers. Nonetheless, the main controller is not
nuclear@26 25 * trivial. Its responsibility is to provide context rows for upsampling/
nuclear@26 26 * rescaling, and doing this in an efficient fashion is a bit tricky.
nuclear@26 27 *
nuclear@26 28 * Postprocessor input data is counted in "row groups". A row group
nuclear@26 29 * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
nuclear@26 30 * sample rows of each component. (We require DCT_scaled_size values to be
nuclear@26 31 * chosen such that these numbers are integers. In practice DCT_scaled_size
nuclear@26 32 * values will likely be powers of two, so we actually have the stronger
nuclear@26 33 * condition that DCT_scaled_size / min_DCT_scaled_size is an integer.)
nuclear@26 34 * Upsampling will typically produce max_v_samp_factor pixel rows from each
nuclear@26 35 * row group (times any additional scale factor that the upsampler is
nuclear@26 36 * applying).
nuclear@26 37 *
nuclear@26 38 * The coefficient controller will deliver data to us one iMCU row at a time;
nuclear@26 39 * each iMCU row contains v_samp_factor * DCT_scaled_size sample rows, or
nuclear@26 40 * exactly min_DCT_scaled_size row groups. (This amount of data corresponds
nuclear@26 41 * to one row of MCUs when the image is fully interleaved.) Note that the
nuclear@26 42 * number of sample rows varies across components, but the number of row
nuclear@26 43 * groups does not. Some garbage sample rows may be included in the last iMCU
nuclear@26 44 * row at the bottom of the image.
nuclear@26 45 *
nuclear@26 46 * Depending on the vertical scaling algorithm used, the upsampler may need
nuclear@26 47 * access to the sample row(s) above and below its current input row group.
nuclear@26 48 * The upsampler is required to set need_context_rows TRUE at global selection
nuclear@26 49 * time if so. When need_context_rows is FALSE, this controller can simply
nuclear@26 50 * obtain one iMCU row at a time from the coefficient controller and dole it
nuclear@26 51 * out as row groups to the postprocessor.
nuclear@26 52 *
nuclear@26 53 * When need_context_rows is TRUE, this controller guarantees that the buffer
nuclear@26 54 * passed to postprocessing contains at least one row group's worth of samples
nuclear@26 55 * above and below the row group(s) being processed. Note that the context
nuclear@26 56 * rows "above" the first passed row group appear at negative row offsets in
nuclear@26 57 * the passed buffer. At the top and bottom of the image, the required
nuclear@26 58 * context rows are manufactured by duplicating the first or last real sample
nuclear@26 59 * row; this avoids having special cases in the upsampling inner loops.
nuclear@26 60 *
nuclear@26 61 * The amount of context is fixed at one row group just because that's a
nuclear@26 62 * convenient number for this controller to work with. The existing
nuclear@26 63 * upsamplers really only need one sample row of context. An upsampler
nuclear@26 64 * supporting arbitrary output rescaling might wish for more than one row
nuclear@26 65 * group of context when shrinking the image; tough, we don't handle that.
nuclear@26 66 * (This is justified by the assumption that downsizing will be handled mostly
nuclear@26 67 * by adjusting the DCT_scaled_size values, so that the actual scale factor at
nuclear@26 68 * the upsample step needn't be much less than one.)
nuclear@26 69 *
nuclear@26 70 * To provide the desired context, we have to retain the last two row groups
nuclear@26 71 * of one iMCU row while reading in the next iMCU row. (The last row group
nuclear@26 72 * can't be processed until we have another row group for its below-context,
nuclear@26 73 * and so we have to save the next-to-last group too for its above-context.)
nuclear@26 74 * We could do this most simply by copying data around in our buffer, but
nuclear@26 75 * that'd be very slow. We can avoid copying any data by creating a rather
nuclear@26 76 * strange pointer structure. Here's how it works. We allocate a workspace
nuclear@26 77 * consisting of M+2 row groups (where M = min_DCT_scaled_size is the number
nuclear@26 78 * of row groups per iMCU row). We create two sets of redundant pointers to
nuclear@26 79 * the workspace. Labeling the physical row groups 0 to M+1, the synthesized
nuclear@26 80 * pointer lists look like this:
nuclear@26 81 * M+1 M-1
nuclear@26 82 * master pointer --> 0 master pointer --> 0
nuclear@26 83 * 1 1
nuclear@26 84 * ... ...
nuclear@26 85 * M-3 M-3
nuclear@26 86 * M-2 M
nuclear@26 87 * M-1 M+1
nuclear@26 88 * M M-2
nuclear@26 89 * M+1 M-1
nuclear@26 90 * 0 0
nuclear@26 91 * We read alternate iMCU rows using each master pointer; thus the last two
nuclear@26 92 * row groups of the previous iMCU row remain un-overwritten in the workspace.
nuclear@26 93 * The pointer lists are set up so that the required context rows appear to
nuclear@26 94 * be adjacent to the proper places when we pass the pointer lists to the
nuclear@26 95 * upsampler.
nuclear@26 96 *
nuclear@26 97 * The above pictures describe the normal state of the pointer lists.
nuclear@26 98 * At top and bottom of the image, we diddle the pointer lists to duplicate
nuclear@26 99 * the first or last sample row as necessary (this is cheaper than copying
nuclear@26 100 * sample rows around).
nuclear@26 101 *
nuclear@26 102 * This scheme breaks down if M < 2, ie, min_DCT_scaled_size is 1. In that
nuclear@26 103 * situation each iMCU row provides only one row group so the buffering logic
nuclear@26 104 * must be different (eg, we must read two iMCU rows before we can emit the
nuclear@26 105 * first row group). For now, we simply do not support providing context
nuclear@26 106 * rows when min_DCT_scaled_size is 1. That combination seems unlikely to
nuclear@26 107 * be worth providing --- if someone wants a 1/8th-size preview, they probably
nuclear@26 108 * want it quick and dirty, so a context-free upsampler is sufficient.
nuclear@26 109 */
nuclear@26 110
nuclear@26 111
nuclear@26 112 /* Private buffer controller object */
nuclear@26 113
nuclear@26 114 typedef struct {
nuclear@26 115 struct jpeg_d_main_controller pub; /* public fields */
nuclear@26 116
nuclear@26 117 /* Pointer to allocated workspace (M or M+2 row groups). */
nuclear@26 118 JSAMPARRAY buffer[MAX_COMPONENTS];
nuclear@26 119
nuclear@26 120 boolean buffer_full; /* Have we gotten an iMCU row from decoder? */
nuclear@26 121 JDIMENSION rowgroup_ctr; /* counts row groups output to postprocessor */
nuclear@26 122
nuclear@26 123 /* Remaining fields are only used in the context case. */
nuclear@26 124
nuclear@26 125 /* These are the master pointers to the funny-order pointer lists. */
nuclear@26 126 JSAMPIMAGE xbuffer[2]; /* pointers to weird pointer lists */
nuclear@26 127
nuclear@26 128 int whichptr; /* indicates which pointer set is now in use */
nuclear@26 129 int context_state; /* process_data state machine status */
nuclear@26 130 JDIMENSION rowgroups_avail; /* row groups available to postprocessor */
nuclear@26 131 JDIMENSION iMCU_row_ctr; /* counts iMCU rows to detect image top/bot */
nuclear@26 132 } my_main_controller;
nuclear@26 133
nuclear@26 134 typedef my_main_controller * my_main_ptr;
nuclear@26 135
nuclear@26 136 /* context_state values: */
nuclear@26 137 #define CTX_PREPARE_FOR_IMCU 0 /* need to prepare for MCU row */
nuclear@26 138 #define CTX_PROCESS_IMCU 1 /* feeding iMCU to postprocessor */
nuclear@26 139 #define CTX_POSTPONED_ROW 2 /* feeding postponed row group */
nuclear@26 140
nuclear@26 141
nuclear@26 142 /* Forward declarations */
nuclear@26 143 METHODDEF(void) process_data_simple_main
nuclear@26 144 JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf,
nuclear@26 145 JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail));
nuclear@26 146 METHODDEF(void) process_data_context_main
nuclear@26 147 JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf,
nuclear@26 148 JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail));
nuclear@26 149 #ifdef QUANT_2PASS_SUPPORTED
nuclear@26 150 METHODDEF(void) process_data_crank_post
nuclear@26 151 JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf,
nuclear@26 152 JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail));
nuclear@26 153 #endif
nuclear@26 154
nuclear@26 155
nuclear@26 156 LOCAL(void)
nuclear@26 157 alloc_funny_pointers (j_decompress_ptr cinfo)
nuclear@26 158 /* Allocate space for the funny pointer lists.
nuclear@26 159 * This is done only once, not once per pass.
nuclear@26 160 */
nuclear@26 161 {
nuclear@26 162 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@26 163 int ci, rgroup;
nuclear@26 164 int M = cinfo->min_DCT_scaled_size;
nuclear@26 165 jpeg_component_info *compptr;
nuclear@26 166 JSAMPARRAY xbuf;
nuclear@26 167
nuclear@26 168 /* Get top-level space for component array pointers.
nuclear@26 169 * We alloc both arrays with one call to save a few cycles.
nuclear@26 170 */
nuclear@26 171 main->xbuffer[0] = (JSAMPIMAGE)
nuclear@26 172 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26 173 cinfo->num_components * 2 * SIZEOF(JSAMPARRAY));
nuclear@26 174 main->xbuffer[1] = main->xbuffer[0] + cinfo->num_components;
nuclear@26 175
nuclear@26 176 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@26 177 ci++, compptr++) {
nuclear@26 178 rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@26 179 cinfo->min_DCT_scaled_size; /* height of a row group of component */
nuclear@26 180 /* Get space for pointer lists --- M+4 row groups in each list.
nuclear@26 181 * We alloc both pointer lists with one call to save a few cycles.
nuclear@26 182 */
nuclear@26 183 xbuf = (JSAMPARRAY)
nuclear@26 184 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26 185 2 * (rgroup * (M + 4)) * SIZEOF(JSAMPROW));
nuclear@26 186 xbuf += rgroup; /* want one row group at negative offsets */
nuclear@26 187 main->xbuffer[0][ci] = xbuf;
nuclear@26 188 xbuf += rgroup * (M + 4);
nuclear@26 189 main->xbuffer[1][ci] = xbuf;
nuclear@26 190 }
nuclear@26 191 }
nuclear@26 192
nuclear@26 193
nuclear@26 194 LOCAL(void)
nuclear@26 195 make_funny_pointers (j_decompress_ptr cinfo)
nuclear@26 196 /* Create the funny pointer lists discussed in the comments above.
nuclear@26 197 * The actual workspace is already allocated (in main->buffer),
nuclear@26 198 * and the space for the pointer lists is allocated too.
nuclear@26 199 * This routine just fills in the curiously ordered lists.
nuclear@26 200 * This will be repeated at the beginning of each pass.
nuclear@26 201 */
nuclear@26 202 {
nuclear@26 203 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@26 204 int ci, i, rgroup;
nuclear@26 205 int M = cinfo->min_DCT_scaled_size;
nuclear@26 206 jpeg_component_info *compptr;
nuclear@26 207 JSAMPARRAY buf, xbuf0, xbuf1;
nuclear@26 208
nuclear@26 209 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@26 210 ci++, compptr++) {
nuclear@26 211 rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@26 212 cinfo->min_DCT_scaled_size; /* height of a row group of component */
nuclear@26 213 xbuf0 = main->xbuffer[0][ci];
nuclear@26 214 xbuf1 = main->xbuffer[1][ci];
nuclear@26 215 /* First copy the workspace pointers as-is */
nuclear@26 216 buf = main->buffer[ci];
nuclear@26 217 for (i = 0; i < rgroup * (M + 2); i++) {
nuclear@26 218 xbuf0[i] = xbuf1[i] = buf[i];
nuclear@26 219 }
nuclear@26 220 /* In the second list, put the last four row groups in swapped order */
nuclear@26 221 for (i = 0; i < rgroup * 2; i++) {
nuclear@26 222 xbuf1[rgroup*(M-2) + i] = buf[rgroup*M + i];
nuclear@26 223 xbuf1[rgroup*M + i] = buf[rgroup*(M-2) + i];
nuclear@26 224 }
nuclear@26 225 /* The wraparound pointers at top and bottom will be filled later
nuclear@26 226 * (see set_wraparound_pointers, below). Initially we want the "above"
nuclear@26 227 * pointers to duplicate the first actual data line. This only needs
nuclear@26 228 * to happen in xbuffer[0].
nuclear@26 229 */
nuclear@26 230 for (i = 0; i < rgroup; i++) {
nuclear@26 231 xbuf0[i - rgroup] = xbuf0[0];
nuclear@26 232 }
nuclear@26 233 }
nuclear@26 234 }
nuclear@26 235
nuclear@26 236
nuclear@26 237 LOCAL(void)
nuclear@26 238 set_wraparound_pointers (j_decompress_ptr cinfo)
nuclear@26 239 /* Set up the "wraparound" pointers at top and bottom of the pointer lists.
nuclear@26 240 * This changes the pointer list state from top-of-image to the normal state.
nuclear@26 241 */
nuclear@26 242 {
nuclear@26 243 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@26 244 int ci, i, rgroup;
nuclear@26 245 int M = cinfo->min_DCT_scaled_size;
nuclear@26 246 jpeg_component_info *compptr;
nuclear@26 247 JSAMPARRAY xbuf0, xbuf1;
nuclear@26 248
nuclear@26 249 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@26 250 ci++, compptr++) {
nuclear@26 251 rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@26 252 cinfo->min_DCT_scaled_size; /* height of a row group of component */
nuclear@26 253 xbuf0 = main->xbuffer[0][ci];
nuclear@26 254 xbuf1 = main->xbuffer[1][ci];
nuclear@26 255 for (i = 0; i < rgroup; i++) {
nuclear@26 256 xbuf0[i - rgroup] = xbuf0[rgroup*(M+1) + i];
nuclear@26 257 xbuf1[i - rgroup] = xbuf1[rgroup*(M+1) + i];
nuclear@26 258 xbuf0[rgroup*(M+2) + i] = xbuf0[i];
nuclear@26 259 xbuf1[rgroup*(M+2) + i] = xbuf1[i];
nuclear@26 260 }
nuclear@26 261 }
nuclear@26 262 }
nuclear@26 263
nuclear@26 264
nuclear@26 265 LOCAL(void)
nuclear@26 266 set_bottom_pointers (j_decompress_ptr cinfo)
nuclear@26 267 /* Change the pointer lists to duplicate the last sample row at the bottom
nuclear@26 268 * of the image. whichptr indicates which xbuffer holds the final iMCU row.
nuclear@26 269 * Also sets rowgroups_avail to indicate number of nondummy row groups in row.
nuclear@26 270 */
nuclear@26 271 {
nuclear@26 272 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@26 273 int ci, i, rgroup, iMCUheight, rows_left;
nuclear@26 274 jpeg_component_info *compptr;
nuclear@26 275 JSAMPARRAY xbuf;
nuclear@26 276
nuclear@26 277 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@26 278 ci++, compptr++) {
nuclear@26 279 /* Count sample rows in one iMCU row and in one row group */
nuclear@26 280 iMCUheight = compptr->v_samp_factor * compptr->DCT_scaled_size;
nuclear@26 281 rgroup = iMCUheight / cinfo->min_DCT_scaled_size;
nuclear@26 282 /* Count nondummy sample rows remaining for this component */
nuclear@26 283 rows_left = (int) (compptr->downsampled_height % (JDIMENSION) iMCUheight);
nuclear@26 284 if (rows_left == 0) rows_left = iMCUheight;
nuclear@26 285 /* Count nondummy row groups. Should get same answer for each component,
nuclear@26 286 * so we need only do it once.
nuclear@26 287 */
nuclear@26 288 if (ci == 0) {
nuclear@26 289 main->rowgroups_avail = (JDIMENSION) ((rows_left-1) / rgroup + 1);
nuclear@26 290 }
nuclear@26 291 /* Duplicate the last real sample row rgroup*2 times; this pads out the
nuclear@26 292 * last partial rowgroup and ensures at least one full rowgroup of context.
nuclear@26 293 */
nuclear@26 294 xbuf = main->xbuffer[main->whichptr][ci];
nuclear@26 295 for (i = 0; i < rgroup * 2; i++) {
nuclear@26 296 xbuf[rows_left + i] = xbuf[rows_left-1];
nuclear@26 297 }
nuclear@26 298 }
nuclear@26 299 }
nuclear@26 300
nuclear@26 301
nuclear@26 302 /*
nuclear@26 303 * Initialize for a processing pass.
nuclear@26 304 */
nuclear@26 305
nuclear@26 306 METHODDEF(void)
nuclear@26 307 start_pass_main (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
nuclear@26 308 {
nuclear@26 309 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@26 310
nuclear@26 311 switch (pass_mode) {
nuclear@26 312 case JBUF_PASS_THRU:
nuclear@26 313 if (cinfo->upsample->need_context_rows) {
nuclear@26 314 main->pub.process_data = process_data_context_main;
nuclear@26 315 make_funny_pointers(cinfo); /* Create the xbuffer[] lists */
nuclear@26 316 main->whichptr = 0; /* Read first iMCU row into xbuffer[0] */
nuclear@26 317 main->context_state = CTX_PREPARE_FOR_IMCU;
nuclear@26 318 main->iMCU_row_ctr = 0;
nuclear@26 319 } else {
nuclear@26 320 /* Simple case with no context needed */
nuclear@26 321 main->pub.process_data = process_data_simple_main;
nuclear@26 322 }
nuclear@26 323 main->buffer_full = FALSE; /* Mark buffer empty */
nuclear@26 324 main->rowgroup_ctr = 0;
nuclear@26 325 break;
nuclear@26 326 #ifdef QUANT_2PASS_SUPPORTED
nuclear@26 327 case JBUF_CRANK_DEST:
nuclear@26 328 /* For last pass of 2-pass quantization, just crank the postprocessor */
nuclear@26 329 main->pub.process_data = process_data_crank_post;
nuclear@26 330 break;
nuclear@26 331 #endif
nuclear@26 332 default:
nuclear@26 333 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
nuclear@26 334 break;
nuclear@26 335 }
nuclear@26 336 }
nuclear@26 337
nuclear@26 338
nuclear@26 339 /*
nuclear@26 340 * Process some data.
nuclear@26 341 * This handles the simple case where no context is required.
nuclear@26 342 */
nuclear@26 343
nuclear@26 344 METHODDEF(void)
nuclear@26 345 process_data_simple_main (j_decompress_ptr cinfo,
nuclear@26 346 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26 347 JDIMENSION out_rows_avail)
nuclear@26 348 {
nuclear@26 349 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@26 350 JDIMENSION rowgroups_avail;
nuclear@26 351
nuclear@26 352 /* Read input data if we haven't filled the main buffer yet */
nuclear@26 353 if (! main->buffer_full) {
nuclear@26 354 if (! (*cinfo->coef->decompress_data) (cinfo, main->buffer))
nuclear@26 355 return; /* suspension forced, can do nothing more */
nuclear@26 356 main->buffer_full = TRUE; /* OK, we have an iMCU row to work with */
nuclear@26 357 }
nuclear@26 358
nuclear@26 359 /* There are always min_DCT_scaled_size row groups in an iMCU row. */
nuclear@26 360 rowgroups_avail = (JDIMENSION) cinfo->min_DCT_scaled_size;
nuclear@26 361 /* Note: at the bottom of the image, we may pass extra garbage row groups
nuclear@26 362 * to the postprocessor. The postprocessor has to check for bottom
nuclear@26 363 * of image anyway (at row resolution), so no point in us doing it too.
nuclear@26 364 */
nuclear@26 365
nuclear@26 366 /* Feed the postprocessor */
nuclear@26 367 (*cinfo->post->post_process_data) (cinfo, main->buffer,
nuclear@26 368 &main->rowgroup_ctr, rowgroups_avail,
nuclear@26 369 output_buf, out_row_ctr, out_rows_avail);
nuclear@26 370
nuclear@26 371 /* Has postprocessor consumed all the data yet? If so, mark buffer empty */
nuclear@26 372 if (main->rowgroup_ctr >= rowgroups_avail) {
nuclear@26 373 main->buffer_full = FALSE;
nuclear@26 374 main->rowgroup_ctr = 0;
nuclear@26 375 }
nuclear@26 376 }
nuclear@26 377
nuclear@26 378
nuclear@26 379 /*
nuclear@26 380 * Process some data.
nuclear@26 381 * This handles the case where context rows must be provided.
nuclear@26 382 */
nuclear@26 383
nuclear@26 384 METHODDEF(void)
nuclear@26 385 process_data_context_main (j_decompress_ptr cinfo,
nuclear@26 386 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26 387 JDIMENSION out_rows_avail)
nuclear@26 388 {
nuclear@26 389 my_main_ptr main = (my_main_ptr) cinfo->main;
nuclear@26 390
nuclear@26 391 /* Read input data if we haven't filled the main buffer yet */
nuclear@26 392 if (! main->buffer_full) {
nuclear@26 393 if (! (*cinfo->coef->decompress_data) (cinfo,
nuclear@26 394 main->xbuffer[main->whichptr]))
nuclear@26 395 return; /* suspension forced, can do nothing more */
nuclear@26 396 main->buffer_full = TRUE; /* OK, we have an iMCU row to work with */
nuclear@26 397 main->iMCU_row_ctr++; /* count rows received */
nuclear@26 398 }
nuclear@26 399
nuclear@26 400 /* Postprocessor typically will not swallow all the input data it is handed
nuclear@26 401 * in one call (due to filling the output buffer first). Must be prepared
nuclear@26 402 * to exit and restart. This switch lets us keep track of how far we got.
nuclear@26 403 * Note that each case falls through to the next on successful completion.
nuclear@26 404 */
nuclear@26 405 switch (main->context_state) {
nuclear@26 406 case CTX_POSTPONED_ROW:
nuclear@26 407 /* Call postprocessor using previously set pointers for postponed row */
nuclear@26 408 (*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr],
nuclear@26 409 &main->rowgroup_ctr, main->rowgroups_avail,
nuclear@26 410 output_buf, out_row_ctr, out_rows_avail);
nuclear@26 411 if (main->rowgroup_ctr < main->rowgroups_avail)
nuclear@26 412 return; /* Need to suspend */
nuclear@26 413 main->context_state = CTX_PREPARE_FOR_IMCU;
nuclear@26 414 if (*out_row_ctr >= out_rows_avail)
nuclear@26 415 return; /* Postprocessor exactly filled output buf */
nuclear@26 416 /*FALLTHROUGH*/
nuclear@26 417 case CTX_PREPARE_FOR_IMCU:
nuclear@26 418 /* Prepare to process first M-1 row groups of this iMCU row */
nuclear@26 419 main->rowgroup_ctr = 0;
nuclear@26 420 main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_scaled_size - 1);
nuclear@26 421 /* Check for bottom of image: if so, tweak pointers to "duplicate"
nuclear@26 422 * the last sample row, and adjust rowgroups_avail to ignore padding rows.
nuclear@26 423 */
nuclear@26 424 if (main->iMCU_row_ctr == cinfo->total_iMCU_rows)
nuclear@26 425 set_bottom_pointers(cinfo);
nuclear@26 426 main->context_state = CTX_PROCESS_IMCU;
nuclear@26 427 /*FALLTHROUGH*/
nuclear@26 428 case CTX_PROCESS_IMCU:
nuclear@26 429 /* Call postprocessor using previously set pointers */
nuclear@26 430 (*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr],
nuclear@26 431 &main->rowgroup_ctr, main->rowgroups_avail,
nuclear@26 432 output_buf, out_row_ctr, out_rows_avail);
nuclear@26 433 if (main->rowgroup_ctr < main->rowgroups_avail)
nuclear@26 434 return; /* Need to suspend */
nuclear@26 435 /* After the first iMCU, change wraparound pointers to normal state */
nuclear@26 436 if (main->iMCU_row_ctr == 1)
nuclear@26 437 set_wraparound_pointers(cinfo);
nuclear@26 438 /* Prepare to load new iMCU row using other xbuffer list */
nuclear@26 439 main->whichptr ^= 1; /* 0=>1 or 1=>0 */
nuclear@26 440 main->buffer_full = FALSE;
nuclear@26 441 /* Still need to process last row group of this iMCU row, */
nuclear@26 442 /* which is saved at index M+1 of the other xbuffer */
nuclear@26 443 main->rowgroup_ctr = (JDIMENSION) (cinfo->min_DCT_scaled_size + 1);
nuclear@26 444 main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_scaled_size + 2);
nuclear@26 445 main->context_state = CTX_POSTPONED_ROW;
nuclear@26 446 }
nuclear@26 447 }
nuclear@26 448
nuclear@26 449
nuclear@26 450 /*
nuclear@26 451 * Process some data.
nuclear@26 452 * Final pass of two-pass quantization: just call the postprocessor.
nuclear@26 453 * Source data will be the postprocessor controller's internal buffer.
nuclear@26 454 */
nuclear@26 455
nuclear@26 456 #ifdef QUANT_2PASS_SUPPORTED
nuclear@26 457
nuclear@26 458 METHODDEF(void)
nuclear@26 459 process_data_crank_post (j_decompress_ptr cinfo,
nuclear@26 460 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26 461 JDIMENSION out_rows_avail)
nuclear@26 462 {
nuclear@26 463 (*cinfo->post->post_process_data) (cinfo, (JSAMPIMAGE) NULL,
nuclear@26 464 (JDIMENSION *) NULL, (JDIMENSION) 0,
nuclear@26 465 output_buf, out_row_ctr, out_rows_avail);
nuclear@26 466 }
nuclear@26 467
nuclear@26 468 #endif /* QUANT_2PASS_SUPPORTED */
nuclear@26 469
nuclear@26 470
nuclear@26 471 /*
nuclear@26 472 * Initialize main buffer controller.
nuclear@26 473 */
nuclear@26 474
nuclear@26 475 GLOBAL(void)
nuclear@26 476 jinit_d_main_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
nuclear@26 477 {
nuclear@26 478 my_main_ptr main;
nuclear@26 479 int ci, rgroup, ngroups;
nuclear@26 480 jpeg_component_info *compptr;
nuclear@26 481
nuclear@26 482 main = (my_main_ptr)
nuclear@26 483 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26 484 SIZEOF(my_main_controller));
nuclear@26 485 cinfo->main = (struct jpeg_d_main_controller *) main;
nuclear@26 486 main->pub.start_pass = start_pass_main;
nuclear@26 487
nuclear@26 488 if (need_full_buffer) /* shouldn't happen */
nuclear@26 489 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
nuclear@26 490
nuclear@26 491 /* Allocate the workspace.
nuclear@26 492 * ngroups is the number of row groups we need.
nuclear@26 493 */
nuclear@26 494 if (cinfo->upsample->need_context_rows) {
nuclear@26 495 if (cinfo->min_DCT_scaled_size < 2) /* unsupported, see comments above */
nuclear@26 496 ERREXIT(cinfo, JERR_NOTIMPL);
nuclear@26 497 alloc_funny_pointers(cinfo); /* Alloc space for xbuffer[] lists */
nuclear@26 498 ngroups = cinfo->min_DCT_scaled_size + 2;
nuclear@26 499 } else {
nuclear@26 500 ngroups = cinfo->min_DCT_scaled_size;
nuclear@26 501 }
nuclear@26 502
nuclear@26 503 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@26 504 ci++, compptr++) {
nuclear@26 505 rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
nuclear@26 506 cinfo->min_DCT_scaled_size; /* height of a row group of component */
nuclear@26 507 main->buffer[ci] = (*cinfo->mem->alloc_sarray)
nuclear@26 508 ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26 509 compptr->width_in_blocks * compptr->DCT_scaled_size,
nuclear@26 510 (JDIMENSION) (rgroup * ngroups));
nuclear@26 511 }
nuclear@26 512 }