jddiffct.c

   1 /*
   2  * jddiffct.c
   3  *
   4  * This file was part of the Independent JPEG Group's software:
   5  * Copyright (C) 1994-1997, Thomas G. Lane.
   6  * Lossless JPEG Modifications:
   7  * Copyright (C) 1999, Ken Murchison.
   8  * libjpeg-turbo Modifications:
   9  * Copyright (C) 2022, D. R. Commander.
  10  * For conditions of distribution and use, see the accompanying README.ijg
  11  * file.
  12  *
  13  * This file contains the [un]difference buffer controller for decompression.
  14  * This controller is the top level of the lossless JPEG decompressor proper.
  15  * The difference buffer lies between the entropy decoding and
  16  * prediction/undifferencing steps.  The undifference buffer lies between the
  17  * prediction/undifferencing and scaling steps.
  18  *
  19  * In buffered-image mode, this controller is the interface between
  20  * input-oriented processing and output-oriented processing.
  21  */
  22
  23 #define JPEG_INTERNALS
  24 #include "jinclude.h"
  25 #include "jpeglib.h"
  26 #include "jlossls.h"            /* Private declarations for lossless codec */
  27
  28
  29 #ifdef D_LOSSLESS_SUPPORTED
  30
  31 /* Private buffer controller object */
  32
  33 typedef struct {
  34   struct jpeg_d_coef_controller pub; /* public fields */
  35
  36   /* These variables keep track of the current location of the input side. */
  37   /* cinfo->input_iMCU_row is also used for this. */
  38   JDIMENSION MCU_ctr;           /* counts MCUs processed in current row */
  39   unsigned int restart_rows_to_go;      /* MCU rows left in this restart
  40                                            interval */
  41   unsigned int MCU_vert_offset;         /* counts MCU rows within iMCU row */
  42   unsigned int MCU_rows_per_iMCU_row;   /* number of such rows needed */
  43
  44   /* The output side's location is represented by cinfo->output_iMCU_row. */
  45
  46   JDIFFARRAY diff_buf[MAX_COMPONENTS];  /* iMCU row of differences */
  47   JDIFFARRAY undiff_buf[MAX_COMPONENTS]; /* iMCU row of undiff'd samples */
  48
  49 #ifdef D_MULTISCAN_FILES_SUPPORTED
  50   /* In multi-pass modes, we need a virtual sample array for each component. */
  51   jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
  52 #endif
  53 } my_diff_controller;
  54
  55 typedef my_diff_controller *my_diff_ptr;
  56
  57 /* Forward declarations */
  58 METHODDEF(int) decompress_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf);
  59 #ifdef D_MULTISCAN_FILES_SUPPORTED
  60 METHODDEF(int) output_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf);
  61 #endif
  62
  63
  64 LOCAL(void)
  65 start_iMCU_row(j_decompress_ptr cinfo)
  66 /* Reset within-iMCU-row counters for a new row (input side) */
  67 {
  68   my_diff_ptr diff = (my_diff_ptr)cinfo->coef;
  69
  70   /* In an interleaved scan, an MCU row is the same as an iMCU row.
  71    * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
  72    * But at the bottom of the image, process only what's left.
  73    */
  74   if (cinfo->comps_in_scan > 1) {
  75     diff->MCU_rows_per_iMCU_row = 1;
  76   } else {
  77     if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1))
  78       diff->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
  79     else
  80       diff->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
  81   }
  82
  83   diff->MCU_ctr = 0;
  84   diff->MCU_vert_offset = 0;
  85 }
  86
  87
  88 /*
  89  * Initialize for an input processing pass.
  90  */
  91
  92 METHODDEF(void)
  93 start_input_pass(j_decompress_ptr cinfo)
  94 {
  95   my_diff_ptr diff = (my_diff_ptr)cinfo->coef;
  96
  97   /* Because it is hitching a ride on the jpeg_inverse_dct struct,
  98    * start_pass_lossless() will be called at the start of the output pass.
  99    * This ensures that it will be called at the start of the input pass as
 100    * well.
 101    */
 102   (*cinfo->idct->start_pass) (cinfo);
 103
 104   /* Check that the restart interval is an integer multiple of the number
 105    * of MCUs in an MCU row.
 106    */
 107   if (cinfo->restart_interval % cinfo->MCUs_per_row != 0)
 108     ERREXIT2(cinfo, JERR_BAD_RESTART,
 109              cinfo->restart_interval, cinfo->MCUs_per_row);
 110
 111   /* Initialize restart counter */
 112   diff->restart_rows_to_go = cinfo->restart_interval / cinfo->MCUs_per_row;
 113
 114   cinfo->input_iMCU_row = 0;
 115   start_iMCU_row(cinfo);
 116 }
 117
 118
 119 /*
 120  * Check for a restart marker & resynchronize decoder, undifferencer.
 121  * Returns FALSE if must suspend.
 122  */
 123
 124 METHODDEF(boolean)
 125 process_restart(j_decompress_ptr cinfo)
 126 {
 127   my_diff_ptr diff = (my_diff_ptr)cinfo->coef;
 128
 129   if (!(*cinfo->entropy->process_restart) (cinfo))
 130     return FALSE;
 131
 132   (*cinfo->idct->start_pass) (cinfo);
 133
 134   /* Reset restart counter */
 135   diff->restart_rows_to_go = cinfo->restart_interval / cinfo->MCUs_per_row;
 136
 137   return TRUE;
 138 }
 139
 140
 141 /*
 142  * Initialize for an output processing pass.
 143  */
 144
 145 METHODDEF(void)
 146 start_output_pass(j_decompress_ptr cinfo)
 147 {
 148   cinfo->output_iMCU_row = 0;
 149 }
 150
 151
 152 /*
 153  * Decompress and return some data in the supplied buffer.
 154  * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
 155  * Input and output must run in lockstep since we have only a one-MCU buffer.
 156  * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 157  *
 158  * NB: output_buf contains a plane for each component in image,
 159  * which we index according to the component's SOF position.
 160  */
 161
 162 METHODDEF(int)
 163 decompress_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf)
 164 {
 165   my_diff_ptr diff = (my_diff_ptr)cinfo->coef;
 166   lossless_decomp_ptr losslessd = (lossless_decomp_ptr)cinfo->idct;
 167   JDIMENSION MCU_col_num;       /* index of current MCU within row */
 168   JDIMENSION MCU_count;         /* number of MCUs decoded */
 169   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
 170   int ci, compi, row, prev_row;
 171   unsigned int yoffset;
 172   jpeg_component_info *compptr;
 173
 174   /* Loop to process as much as one whole iMCU row */
 175   for (yoffset = diff->MCU_vert_offset; yoffset < diff->MCU_rows_per_iMCU_row;
 176        yoffset++) {
 177
 178     /* Process restart marker if needed; may have to suspend */
 179     if (cinfo->restart_interval) {
 180       if (diff->restart_rows_to_go == 0)
 181         if (!process_restart(cinfo))
 182           return JPEG_SUSPENDED;
 183     }
 184
 185     MCU_col_num = diff->MCU_ctr;
 186     /* Try to fetch an MCU row (or remaining portion of suspended MCU row). */
 187     MCU_count =
 188       (*cinfo->entropy->decode_mcus) (cinfo,
 189                                       diff->diff_buf, yoffset, MCU_col_num,
 190                                       cinfo->MCUs_per_row - MCU_col_num);
 191     if (MCU_count != cinfo->MCUs_per_row - MCU_col_num) {
 192       /* Suspension forced; update state counters and exit */
 193       diff->MCU_vert_offset = yoffset;
 194       diff->MCU_ctr += MCU_count;
 195       return JPEG_SUSPENDED;
 196     }
 197
 198     /* Account for restart interval (no-op if not using restarts) */
 199     if (cinfo->restart_interval)
 200       diff->restart_rows_to_go--;
 201
 202     /* Completed an MCU row, but perhaps not an iMCU row */
 203     diff->MCU_ctr = 0;
 204   }
 205
 206   /*
 207    * Undifference and scale each scanline of the disassembled MCU row
 208    * separately.  We do not process dummy samples at the end of a scanline
 209    * or dummy rows at the end of the image.
 210    */
 211   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 212     compptr = cinfo->cur_comp_info[ci];
 213     compi = compptr->component_index;
 214     for (row = 0, prev_row = compptr->v_samp_factor - 1;
 215          row < (cinfo->input_iMCU_row == last_iMCU_row ?
 216                 compptr->last_row_height : compptr->v_samp_factor);
 217          prev_row = row, row++) {
 218       (*losslessd->predict_undifference[compi])
 219         (cinfo, compi, diff->diff_buf[compi][row],
 220           diff->undiff_buf[compi][prev_row], diff->undiff_buf[compi][row],
 221           compptr->width_in_blocks);
 222       (*losslessd->scaler_scale) (cinfo, diff->undiff_buf[compi][row],
 223                                   output_buf[compi][row],
 224                                   compptr->width_in_blocks);
 225     }
 226   }
 227
 228   /* Completed the iMCU row, advance counters for next one.
 229    *
 230    * NB: output_data will increment output_iMCU_row.
 231    * This counter is not needed for the single-pass case
 232    * or the input side of the multi-pass case.
 233    */
 234   if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
 235     start_iMCU_row(cinfo);
 236     return JPEG_ROW_COMPLETED;
 237   }
 238   /* Completed the scan */
 239   (*cinfo->inputctl->finish_input_pass) (cinfo);
 240   return JPEG_SCAN_COMPLETED;
 241 }
 242
 243
 244 /*
 245  * Dummy consume-input routine for single-pass operation.
 246  */
 247
 248 METHODDEF(int)
 249 dummy_consume_data(j_decompress_ptr cinfo)
 250 {
 251   return JPEG_SUSPENDED;        /* Always indicate nothing was done */
 252 }
 253
 254
 255 #ifdef D_MULTISCAN_FILES_SUPPORTED
 256
 257 /*
 258  * Consume input data and store it in the full-image sample buffer.
 259  * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
 260  * ie, v_samp_factor rows for each component in the scan.
 261  * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 262  */
 263
 264 METHODDEF(int)
 265 consume_data(j_decompress_ptr cinfo)
 266 {
 267   my_diff_ptr diff = (my_diff_ptr)cinfo->coef;
 268   int ci, compi;
 269   _JSAMPARRAY buffer[MAX_COMPS_IN_SCAN];
 270   jpeg_component_info *compptr;
 271
 272   /* Align the virtual buffers for the components used in this scan. */
 273   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 274     compptr = cinfo->cur_comp_info[ci];
 275     compi = compptr->component_index;
 276     buffer[compi] = (_JSAMPARRAY)(*cinfo->mem->access_virt_sarray)
 277       ((j_common_ptr)cinfo, diff->whole_image[compi],
 278        cinfo->input_iMCU_row * compptr->v_samp_factor,
 279        (JDIMENSION)compptr->v_samp_factor, TRUE);
 280   }
 281
 282   return decompress_data(cinfo, buffer);
 283 }
 284
 285
 286 /*
 287  * Output some data from the full-image sample buffer in the multi-pass case.
 288  * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
 289  * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 290  *
 291  * NB: output_buf contains a plane for each component in image.
 292  */
 293
 294 METHODDEF(int)
 295 output_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf)
 296 {
 297   my_diff_ptr diff = (my_diff_ptr)cinfo->coef;
 298   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
 299   int ci, samp_rows, row;
 300   _JSAMPARRAY buffer;
 301   jpeg_component_info *compptr;
 302
 303   /* Force some input to be done if we are getting ahead of the input. */
 304   while (cinfo->input_scan_number < cinfo->output_scan_number ||
 305          (cinfo->input_scan_number == cinfo->output_scan_number &&
 306           cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
 307     if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
 308       return JPEG_SUSPENDED;
 309   }
 310
 311   /* OK, output from the virtual arrays. */
 312   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 313        ci++, compptr++) {
 314     /* Align the virtual buffer for this component. */
 315     buffer = (_JSAMPARRAY)(*cinfo->mem->access_virt_sarray)
 316       ((j_common_ptr)cinfo, diff->whole_image[ci],
 317        cinfo->output_iMCU_row * compptr->v_samp_factor,
 318        (JDIMENSION)compptr->v_samp_factor, FALSE);
 319
 320     if (cinfo->output_iMCU_row < last_iMCU_row)
 321       samp_rows = compptr->v_samp_factor;
 322     else {
 323       /* NB: can't use last_row_height here; it is input-side-dependent! */
 324       samp_rows = (int)(compptr->height_in_blocks % compptr->v_samp_factor);
 325       if (samp_rows == 0) samp_rows = compptr->v_samp_factor;
 326     }
 327
 328     for (row = 0; row < samp_rows; row++) {
 329       memcpy(output_buf[ci][row], buffer[row],
 330              compptr->width_in_blocks * sizeof(_JSAMPLE));
 331     }
 332   }
 333
 334   if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
 335     return JPEG_ROW_COMPLETED;
 336   return JPEG_SCAN_COMPLETED;
 337 }
 338
 339 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 340
 341
 342 /*
 343  * Initialize difference buffer controller.
 344  */
 345
 346 GLOBAL(void)
 347 _jinit_d_diff_controller(j_decompress_ptr cinfo, boolean need_full_buffer)
 348 {
 349   my_diff_ptr diff;
 350   int ci;
 351   jpeg_component_info *compptr;
 352
 353   diff = (my_diff_ptr)
 354     (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
 355                                 sizeof(my_diff_controller));
 356   cinfo->coef = (struct jpeg_d_coef_controller *)diff;
 357   diff->pub.start_input_pass = start_input_pass;
 358   diff->pub.start_output_pass = start_output_pass;
 359
 360   /* Create the [un]difference buffers. */
 361   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 362        ci++, compptr++) {
 363     diff->diff_buf[ci] =
 364       ALLOC_DARRAY(JPOOL_IMAGE,
 365                    (JDIMENSION)jround_up((long)compptr->width_in_blocks,
 366                                          (long)compptr->h_samp_factor),
 367                    (JDIMENSION)compptr->v_samp_factor);
 368     diff->undiff_buf[ci] =
 369       ALLOC_DARRAY(JPOOL_IMAGE,
 370                    (JDIMENSION)jround_up((long)compptr->width_in_blocks,
 371                                          (long)compptr->h_samp_factor),
 372                    (JDIMENSION)compptr->v_samp_factor);
 373   }
 374
 375   if (need_full_buffer) {
 376 #ifdef D_MULTISCAN_FILES_SUPPORTED
 377     /* Allocate a full-image virtual array for each component. */
 378     int access_rows;
 379
 380     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 381          ci++, compptr++) {
 382       access_rows = compptr->v_samp_factor;
 383       diff->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
 384         ((j_common_ptr)cinfo, JPOOL_IMAGE, FALSE,
 385          (JDIMENSION)jround_up((long)compptr->width_in_blocks,
 386                                (long)compptr->h_samp_factor),
 387          (JDIMENSION)jround_up((long)compptr->height_in_blocks,
 388                                (long)compptr->v_samp_factor),
 389          (JDIMENSION)access_rows);
 390     }
 391     diff->pub.consume_data = consume_data;
 392     diff->pub._decompress_data = output_data;
 393 #else
 394     ERREXIT(cinfo, JERR_NOT_COMPILED);
 395 #endif
 396   } else {
 397     diff->pub.consume_data = dummy_consume_data;
 398     diff->pub._decompress_data = decompress_data;
 399     diff->whole_image[0] = NULL; /* flag for no virtual arrays */
 400   }
 401 }
 402
 403 #endif /* D_LOSSLESS_SUPPORTED */