dll/3rdparty/libjpeg/jdcoefct.c

   1 /*
   2  * jdcoefct.c
   3  *
   4  * Copyright (C) 1994-1997, Thomas G. Lane.
   5  * Modified 2002-2011 by Guido Vollbeding.
   6  * This file is part of the Independent JPEG Group's software.
   7  * For conditions of distribution and use, see the accompanying README file.
   8  *
   9  * This file contains the coefficient buffer controller for decompression.
  10  * This controller is the top level of the JPEG decompressor proper.
  11  * The coefficient buffer lies between entropy decoding and inverse-DCT steps.
  12  *
  13  * In buffered-image mode, this controller is the interface between
  14  * input-oriented processing and output-oriented processing.
  15  * Also, the input side (only) is used when reading a file for transcoding.
  16  */
  17
  18 #define JPEG_INTERNALS
  19 #include "jinclude.h"
  20 #include "jpeglib.h"
  21
  22 /* Block smoothing is only applicable for progressive JPEG, so: */
  23 #ifndef D_PROGRESSIVE_SUPPORTED
  24 #undef BLOCK_SMOOTHING_SUPPORTED
  25 #endif
  26
  27 /* Private buffer controller object */
  28
  29 typedef struct {
  30   struct jpeg_d_coef_controller pub; /* public fields */
  31
  32   /* These variables keep track of the current location of the input side. */
  33   /* cinfo->input_iMCU_row is also used for this. */
  34   JDIMENSION MCU_ctr;           /* counts MCUs processed in current row */
  35   int MCU_vert_offset;          /* counts MCU rows within iMCU row */
  36   int MCU_rows_per_iMCU_row;    /* number of such rows needed */
  37
  38   /* The output side's location is represented by cinfo->output_iMCU_row. */
  39
  40   /* In single-pass modes, it's sufficient to buffer just one MCU.
  41    * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,
  42    * and let the entropy decoder write into that workspace each time.
  43    * (On 80x86, the workspace is FAR even though it's not really very big;
  44    * this is to keep the module interfaces unchanged when a large coefficient
  45    * buffer is necessary.)
  46    * In multi-pass modes, this array points to the current MCU's blocks
  47    * within the virtual arrays; it is used only by the input side.
  48    */
  49   JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];
  50
  51 #ifdef D_MULTISCAN_FILES_SUPPORTED
  52   /* In multi-pass modes, we need a virtual block array for each component. */
  53   jvirt_barray_ptr whole_image[MAX_COMPONENTS];
  54 #endif
  55
  56 #ifdef BLOCK_SMOOTHING_SUPPORTED
  57   /* When doing block smoothing, we latch coefficient Al values here */
  58   int * coef_bits_latch;
  59 #define SAVED_COEFS  6          /* we save coef_bits[0..5] */
  60 #endif
  61 } my_coef_controller;
  62
  63 typedef my_coef_controller * my_coef_ptr;
  64
  65 /* Forward declarations */
  66 METHODDEF(int) decompress_onepass
  67         JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
  68 #ifdef D_MULTISCAN_FILES_SUPPORTED
  69 METHODDEF(int) decompress_data
  70         JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
  71 #endif
  72 #ifdef BLOCK_SMOOTHING_SUPPORTED
  73 LOCAL(boolean) smoothing_ok JPP((j_decompress_ptr cinfo));
  74 METHODDEF(int) decompress_smooth_data
  75         JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
  76 #endif
  77
  78
  79 LOCAL(void)
  80 start_iMCU_row (j_decompress_ptr cinfo)
  81 /* Reset within-iMCU-row counters for a new row (input side) */
  82 {
  83   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
  84
  85   /* In an interleaved scan, an MCU row is the same as an iMCU row.
  86    * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
  87    * But at the bottom of the image, process only what's left.
  88    */
  89   if (cinfo->comps_in_scan > 1) {
  90     coef->MCU_rows_per_iMCU_row = 1;
  91   } else {
  92     if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1))
  93       coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
  94     else
  95       coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
  96   }
  97
  98   coef->MCU_ctr = 0;
  99   coef->MCU_vert_offset = 0;
 100 }
 101
 102
 103 /*
 104  * Initialize for an input processing pass.
 105  */
 106
 107 METHODDEF(void)
 108 start_input_pass (j_decompress_ptr cinfo)
 109 {
 110   cinfo->input_iMCU_row = 0;
 111   start_iMCU_row(cinfo);
 112 }
 113
 114
 115 /*
 116  * Initialize for an output processing pass.
 117  */
 118
 119 METHODDEF(void)
 120 start_output_pass (j_decompress_ptr cinfo)
 121 {
 122 #ifdef BLOCK_SMOOTHING_SUPPORTED
 123   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
 124
 125   /* If multipass, check to see whether to use block smoothing on this pass */
 126   if (coef->pub.coef_arrays != NULL) {
 127     if (cinfo->do_block_smoothing && smoothing_ok(cinfo))
 128       coef->pub.decompress_data = decompress_smooth_data;
 129     else
 130       coef->pub.decompress_data = decompress_data;
 131   }
 132 #endif
 133   cinfo->output_iMCU_row = 0;
 134 }
 135
 136
 137 /*
 138  * Decompress and return some data in the single-pass case.
 139  * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
 140  * Input and output must run in lockstep since we have only a one-MCU buffer.
 141  * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 142  *
 143  * NB: output_buf contains a plane for each component in image,
 144  * which we index according to the component's SOF position.
 145  */
 146
 147 METHODDEF(int)
 148 decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 149 {
 150   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
 151   JDIMENSION MCU_col_num;       /* index of current MCU within row */
 152   JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
 153   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
 154   int blkn, ci, xindex, yindex, yoffset, useful_width;
 155   JSAMPARRAY output_ptr;
 156   JDIMENSION start_col, output_col;
 157   jpeg_component_info *compptr;
 158   inverse_DCT_method_ptr inverse_DCT;
 159
 160   /* Loop to process as much as one whole iMCU row */
 161   for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
 162        yoffset++) {
 163     for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
 164          MCU_col_num++) {
 165       /* Try to fetch an MCU.  Entropy decoder expects buffer to be zeroed. */
 166       if (cinfo->lim_Se)        /* can bypass in DC only case */
 167         FMEMZERO((void FAR *) coef->MCU_buffer[0],
 168                  (size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK)));
 169       if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
 170         /* Suspension forced; update state counters and exit */
 171         coef->MCU_vert_offset = yoffset;
 172         coef->MCU_ctr = MCU_col_num;
 173         return JPEG_SUSPENDED;
 174       }
 175       /* Determine where data should go in output_buf and do the IDCT thing.
 176        * We skip dummy blocks at the right and bottom edges (but blkn gets
 177        * incremented past them!).  Note the inner loop relies on having
 178        * allocated the MCU_buffer[] blocks sequentially.
 179        */
 180       blkn = 0;                 /* index of current DCT block within MCU */
 181       for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 182         compptr = cinfo->cur_comp_info[ci];
 183         /* Don't bother to IDCT an uninteresting component. */
 184         if (! compptr->component_needed) {
 185           blkn += compptr->MCU_blocks;
 186           continue;
 187         }
 188         inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
 189         useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
 190                                                     : compptr->last_col_width;
 191         output_ptr = output_buf[compptr->component_index] +
 192           yoffset * compptr->DCT_v_scaled_size;
 193         start_col = MCU_col_num * compptr->MCU_sample_width;
 194         for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
 195           if (cinfo->input_iMCU_row < last_iMCU_row ||
 196               yoffset+yindex < compptr->last_row_height) {
 197             output_col = start_col;
 198             for (xindex = 0; xindex < useful_width; xindex++) {
 199               (*inverse_DCT) (cinfo, compptr,
 200                               (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
 201                               output_ptr, output_col);
 202               output_col += compptr->DCT_h_scaled_size;
 203             }
 204           }
 205           blkn += compptr->MCU_width;
 206           output_ptr += compptr->DCT_v_scaled_size;
 207         }
 208       }
 209     }
 210     /* Completed an MCU row, but perhaps not an iMCU row */
 211     coef->MCU_ctr = 0;
 212   }
 213   /* Completed the iMCU row, advance counters for next one */
 214   cinfo->output_iMCU_row++;
 215   if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
 216     start_iMCU_row(cinfo);
 217     return JPEG_ROW_COMPLETED;
 218   }
 219   /* Completed the scan */
 220   (*cinfo->inputctl->finish_input_pass) (cinfo);
 221   return JPEG_SCAN_COMPLETED;
 222 }
 223
 224
 225 /*
 226  * Dummy consume-input routine for single-pass operation.
 227  */
 228
 229 METHODDEF(int)
 230 dummy_consume_data (j_decompress_ptr cinfo)
 231 {
 232   return JPEG_SUSPENDED;        /* Always indicate nothing was done */
 233 }
 234
 235
 236 #ifdef D_MULTISCAN_FILES_SUPPORTED
 237
 238 /*
 239  * Consume input data and store it in the full-image coefficient buffer.
 240  * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
 241  * ie, v_samp_factor block rows for each component in the scan.
 242  * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 243  */
 244
 245 METHODDEF(int)
 246 consume_data (j_decompress_ptr cinfo)
 247 {
 248   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
 249   JDIMENSION MCU_col_num;       /* index of current MCU within row */
 250   int blkn, ci, xindex, yindex, yoffset;
 251   JDIMENSION start_col;
 252   JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
 253   JBLOCKROW buffer_ptr;
 254   jpeg_component_info *compptr;
 255
 256   /* Align the virtual buffers for the components used in this scan. */
 257   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 258     compptr = cinfo->cur_comp_info[ci];
 259     buffer[ci] = (*cinfo->mem->access_virt_barray)
 260       ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
 261        cinfo->input_iMCU_row * compptr->v_samp_factor,
 262        (JDIMENSION) compptr->v_samp_factor, TRUE);
 263     /* Note: entropy decoder expects buffer to be zeroed,
 264      * but this is handled automatically by the memory manager
 265      * because we requested a pre-zeroed array.
 266      */
 267   }
 268
 269   /* Loop to process one whole iMCU row */
 270   for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
 271        yoffset++) {
 272     for (MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
 273          MCU_col_num++) {
 274       /* Construct list of pointers to DCT blocks belonging to this MCU */
 275       blkn = 0;                 /* index of current DCT block within MCU */
 276       for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
 277         compptr = cinfo->cur_comp_info[ci];
 278         start_col = MCU_col_num * compptr->MCU_width;
 279         for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
 280           buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
 281           for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
 282             coef->MCU_buffer[blkn++] = buffer_ptr++;
 283           }
 284         }
 285       }
 286       /* Try to fetch the MCU. */
 287       if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
 288         /* Suspension forced; update state counters and exit */
 289         coef->MCU_vert_offset = yoffset;
 290         coef->MCU_ctr = MCU_col_num;
 291         return JPEG_SUSPENDED;
 292       }
 293     }
 294     /* Completed an MCU row, but perhaps not an iMCU row */
 295     coef->MCU_ctr = 0;
 296   }
 297   /* Completed the iMCU row, advance counters for next one */
 298   if (++(cinfo->input_iMCU_row) < cinfo->total_iMCU_rows) {
 299     start_iMCU_row(cinfo);
 300     return JPEG_ROW_COMPLETED;
 301   }
 302   /* Completed the scan */
 303   (*cinfo->inputctl->finish_input_pass) (cinfo);
 304   return JPEG_SCAN_COMPLETED;
 305 }
 306
 307
 308 /*
 309  * Decompress and return some data in the multi-pass case.
 310  * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
 311  * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 312  *
 313  * NB: output_buf contains a plane for each component in image.
 314  */
 315
 316 METHODDEF(int)
 317 decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 318 {
 319   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
 320   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
 321   JDIMENSION block_num;
 322   int ci, block_row, block_rows;
 323   JBLOCKARRAY buffer;
 324   JBLOCKROW buffer_ptr;
 325   JSAMPARRAY output_ptr;
 326   JDIMENSION output_col;
 327   jpeg_component_info *compptr;
 328   inverse_DCT_method_ptr inverse_DCT;
 329
 330   /* Force some input to be done if we are getting ahead of the input. */
 331   while (cinfo->input_scan_number < cinfo->output_scan_number ||
 332          (cinfo->input_scan_number == cinfo->output_scan_number &&
 333           cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
 334     if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
 335       return JPEG_SUSPENDED;
 336   }
 337
 338   /* OK, output from the virtual arrays. */
 339   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 340        ci++, compptr++) {
 341     /* Don't bother to IDCT an uninteresting component. */
 342     if (! compptr->component_needed)
 343       continue;
 344     /* Align the virtual buffer for this component. */
 345     buffer = (*cinfo->mem->access_virt_barray)
 346       ((j_common_ptr) cinfo, coef->whole_image[ci],
 347        cinfo->output_iMCU_row * compptr->v_samp_factor,
 348        (JDIMENSION) compptr->v_samp_factor, FALSE);
 349     /* Count non-dummy DCT block rows in this iMCU row. */
 350     if (cinfo->output_iMCU_row < last_iMCU_row)
 351       block_rows = compptr->v_samp_factor;
 352     else {
 353       /* NB: can't use last_row_height here; it is input-side-dependent! */
 354       block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
 355       if (block_rows == 0) block_rows = compptr->v_samp_factor;
 356     }
 357     inverse_DCT = cinfo->idct->inverse_DCT[ci];
 358     output_ptr = output_buf[ci];
 359     /* Loop over all DCT blocks to be processed. */
 360     for (block_row = 0; block_row < block_rows; block_row++) {
 361       buffer_ptr = buffer[block_row];
 362       output_col = 0;
 363       for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) {
 364         (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
 365                         output_ptr, output_col);
 366         buffer_ptr++;
 367         output_col += compptr->DCT_h_scaled_size;
 368       }
 369       output_ptr += compptr->DCT_v_scaled_size;
 370     }
 371   }
 372
 373   if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
 374     return JPEG_ROW_COMPLETED;
 375   return JPEG_SCAN_COMPLETED;
 376 }
 377
 378 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 379
 380
 381 #ifdef BLOCK_SMOOTHING_SUPPORTED
 382
 383 /*
 384  * This code applies interblock smoothing as described by section K.8
 385  * of the JPEG standard: the first 5 AC coefficients are estimated from
 386  * the DC values of a DCT block and its 8 neighboring blocks.
 387  * We apply smoothing only for progressive JPEG decoding, and only if
 388  * the coefficients it can estimate are not yet known to full precision.
 389  */
 390
 391 /* Natural-order array positions of the first 5 zigzag-order coefficients */
 392 #define Q01_POS  1
 393 #define Q10_POS  8
 394 #define Q20_POS  16
 395 #define Q11_POS  9
 396 #define Q02_POS  2
 397
 398 /*
 399  * Determine whether block smoothing is applicable and safe.
 400  * We also latch the current states of the coef_bits[] entries for the
 401  * AC coefficients; otherwise, if the input side of the decompressor
 402  * advances into a new scan, we might think the coefficients are known
 403  * more accurately than they really are.
 404  */
 405
 406 LOCAL(boolean)
 407 smoothing_ok (j_decompress_ptr cinfo)
 408 {
 409   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
 410   boolean smoothing_useful = FALSE;
 411   int ci, coefi;
 412   jpeg_component_info *compptr;
 413   JQUANT_TBL * qtable;
 414   int * coef_bits;
 415   int * coef_bits_latch;
 416
 417   if (! cinfo->progressive_mode || cinfo->coef_bits == NULL)
 418     return FALSE;
 419
 420   /* Allocate latch area if not already done */
 421   if (coef->coef_bits_latch == NULL)
 422     coef->coef_bits_latch = (int *)
 423       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 424                                   cinfo->num_components *
 425                                   (SAVED_COEFS * SIZEOF(int)));
 426   coef_bits_latch = coef->coef_bits_latch;
 427
 428   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 429        ci++, compptr++) {
 430     /* All components' quantization values must already be latched. */
 431     if ((qtable = compptr->quant_table) == NULL)
 432       return FALSE;
 433     /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
 434     if (qtable->quantval[0] == 0 ||
 435         qtable->quantval[Q01_POS] == 0 ||
 436         qtable->quantval[Q10_POS] == 0 ||
 437         qtable->quantval[Q20_POS] == 0 ||
 438         qtable->quantval[Q11_POS] == 0 ||
 439         qtable->quantval[Q02_POS] == 0)
 440       return FALSE;
 441     /* DC values must be at least partly known for all components. */
 442     coef_bits = cinfo->coef_bits[ci];
 443     if (coef_bits[0] < 0)
 444       return FALSE;
 445     /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
 446     for (coefi = 1; coefi <= 5; coefi++) {
 447       coef_bits_latch[coefi] = coef_bits[coefi];
 448       if (coef_bits[coefi] != 0)
 449         smoothing_useful = TRUE;
 450     }
 451     coef_bits_latch += SAVED_COEFS;
 452   }
 453
 454   return smoothing_useful;
 455 }
 456
 457
 458 /*
 459  * Variant of decompress_data for use when doing block smoothing.
 460  */
 461
 462 METHODDEF(int)
 463 decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 464 {
 465   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
 466   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
 467   JDIMENSION block_num, last_block_column;
 468   int ci, block_row, block_rows, access_rows;
 469   JBLOCKARRAY buffer;
 470   JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
 471   JSAMPARRAY output_ptr;
 472   JDIMENSION output_col;
 473   jpeg_component_info *compptr;
 474   inverse_DCT_method_ptr inverse_DCT;
 475   boolean first_row, last_row;
 476   JBLOCK workspace;
 477   int *coef_bits;
 478   JQUANT_TBL *quanttbl;
 479   INT32 Q00,Q01,Q02,Q10,Q11,Q20, num;
 480   int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
 481   int Al, pred;
 482
 483   /* Force some input to be done if we are getting ahead of the input. */
 484   while (cinfo->input_scan_number <= cinfo->output_scan_number &&
 485          ! cinfo->inputctl->eoi_reached) {
 486     if (cinfo->input_scan_number == cinfo->output_scan_number) {
 487       /* If input is working on current scan, we ordinarily want it to
 488        * have completed the current row.  But if input scan is DC,
 489        * we want it to keep one row ahead so that next block row's DC
 490        * values are up to date.
 491        */
 492       JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
 493       if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta)
 494         break;
 495     }
 496     if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
 497       return JPEG_SUSPENDED;
 498   }
 499
 500   /* OK, output from the virtual arrays. */
 501   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 502        ci++, compptr++) {
 503     /* Don't bother to IDCT an uninteresting component. */
 504     if (! compptr->component_needed)
 505       continue;
 506     /* Count non-dummy DCT block rows in this iMCU row. */
 507     if (cinfo->output_iMCU_row < last_iMCU_row) {
 508       block_rows = compptr->v_samp_factor;
 509       access_rows = block_rows * 2; /* this and next iMCU row */
 510       last_row = FALSE;
 511     } else {
 512       /* NB: can't use last_row_height here; it is input-side-dependent! */
 513       block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
 514       if (block_rows == 0) block_rows = compptr->v_samp_factor;
 515       access_rows = block_rows; /* this iMCU row only */
 516       last_row = TRUE;
 517     }
 518     /* Align the virtual buffer for this component. */
 519     if (cinfo->output_iMCU_row > 0) {
 520       access_rows += compptr->v_samp_factor; /* prior iMCU row too */
 521       buffer = (*cinfo->mem->access_virt_barray)
 522         ((j_common_ptr) cinfo, coef->whole_image[ci],
 523          (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
 524          (JDIMENSION) access_rows, FALSE);
 525       buffer += compptr->v_samp_factor; /* point to current iMCU row */
 526       first_row = FALSE;
 527     } else {
 528       buffer = (*cinfo->mem->access_virt_barray)
 529         ((j_common_ptr) cinfo, coef->whole_image[ci],
 530          (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE);
 531       first_row = TRUE;
 532     }
 533     /* Fetch component-dependent info */
 534     coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
 535     quanttbl = compptr->quant_table;
 536     Q00 = quanttbl->quantval[0];
 537     Q01 = quanttbl->quantval[Q01_POS];
 538     Q10 = quanttbl->quantval[Q10_POS];
 539     Q20 = quanttbl->quantval[Q20_POS];
 540     Q11 = quanttbl->quantval[Q11_POS];
 541     Q02 = quanttbl->quantval[Q02_POS];
 542     inverse_DCT = cinfo->idct->inverse_DCT[ci];
 543     output_ptr = output_buf[ci];
 544     /* Loop over all DCT blocks to be processed. */
 545     for (block_row = 0; block_row < block_rows; block_row++) {
 546       buffer_ptr = buffer[block_row];
 547       if (first_row && block_row == 0)
 548         prev_block_row = buffer_ptr;
 549       else
 550         prev_block_row = buffer[block_row-1];
 551       if (last_row && block_row == block_rows-1)
 552         next_block_row = buffer_ptr;
 553       else
 554         next_block_row = buffer[block_row+1];
 555       /* We fetch the surrounding DC values using a sliding-register approach.
 556        * Initialize all nine here so as to do the right thing on narrow pics.
 557        */
 558       DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
 559       DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
 560       DC7 = DC8 = DC9 = (int) next_block_row[0][0];
 561       output_col = 0;
 562       last_block_column = compptr->width_in_blocks - 1;
 563       for (block_num = 0; block_num <= last_block_column; block_num++) {
 564         /* Fetch current DCT block into workspace so we can modify it. */
 565         jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
 566         /* Update DC values */
 567         if (block_num < last_block_column) {
 568           DC3 = (int) prev_block_row[1][0];
 569           DC6 = (int) buffer_ptr[1][0];
 570           DC9 = (int) next_block_row[1][0];
 571         }
 572         /* Compute coefficient estimates per K.8.
 573          * An estimate is applied only if coefficient is still zero,
 574          * and is not known to be fully accurate.
 575          */
 576         /* AC01 */
 577         if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
 578           num = 36 * Q00 * (DC4 - DC6);
 579           if (num >= 0) {
 580             pred = (int) (((Q01<<7) + num) / (Q01<<8));
 581             if (Al > 0 && pred >= (1<<Al))
 582               pred = (1<<Al)-1;
 583           } else {
 584             pred = (int) (((Q01<<7) - num) / (Q01<<8));
 585             if (Al > 0 && pred >= (1<<Al))
 586               pred = (1<<Al)-1;
 587             pred = -pred;
 588           }
 589           workspace[1] = (JCOEF) pred;
 590         }
 591         /* AC10 */
 592         if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
 593           num = 36 * Q00 * (DC2 - DC8);
 594           if (num >= 0) {
 595             pred = (int) (((Q10<<7) + num) / (Q10<<8));
 596             if (Al > 0 && pred >= (1<<Al))
 597               pred = (1<<Al)-1;
 598           } else {
 599             pred = (int) (((Q10<<7) - num) / (Q10<<8));
 600             if (Al > 0 && pred >= (1<<Al))
 601               pred = (1<<Al)-1;
 602             pred = -pred;
 603           }
 604           workspace[8] = (JCOEF) pred;
 605         }
 606         /* AC20 */
 607         if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
 608           num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
 609           if (num >= 0) {
 610             pred = (int) (((Q20<<7) + num) / (Q20<<8));
 611             if (Al > 0 && pred >= (1<<Al))
 612               pred = (1<<Al)-1;
 613           } else {
 614             pred = (int) (((Q20<<7) - num) / (Q20<<8));
 615             if (Al > 0 && pred >= (1<<Al))
 616               pred = (1<<Al)-1;
 617             pred = -pred;
 618           }
 619           workspace[16] = (JCOEF) pred;
 620         }
 621         /* AC11 */
 622         if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
 623           num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
 624           if (num >= 0) {
 625             pred = (int) (((Q11<<7) + num) / (Q11<<8));
 626             if (Al > 0 && pred >= (1<<Al))
 627               pred = (1<<Al)-1;
 628           } else {
 629             pred = (int) (((Q11<<7) - num) / (Q11<<8));
 630             if (Al > 0 && pred >= (1<<Al))
 631               pred = (1<<Al)-1;
 632             pred = -pred;
 633           }
 634           workspace[9] = (JCOEF) pred;
 635         }
 636         /* AC02 */
 637         if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
 638           num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
 639           if (num >= 0) {
 640             pred = (int) (((Q02<<7) + num) / (Q02<<8));
 641             if (Al > 0 && pred >= (1<<Al))
 642               pred = (1<<Al)-1;
 643           } else {
 644             pred = (int) (((Q02<<7) - num) / (Q02<<8));
 645             if (Al > 0 && pred >= (1<<Al))
 646               pred = (1<<Al)-1;
 647             pred = -pred;
 648           }
 649           workspace[2] = (JCOEF) pred;
 650         }
 651         /* OK, do the IDCT */
 652         (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
 653                         output_ptr, output_col);
 654         /* Advance for next column */
 655         DC1 = DC2; DC2 = DC3;
 656         DC4 = DC5; DC5 = DC6;
 657         DC7 = DC8; DC8 = DC9;
 658         buffer_ptr++, prev_block_row++, next_block_row++;
 659         output_col += compptr->DCT_h_scaled_size;
 660       }
 661       output_ptr += compptr->DCT_v_scaled_size;
 662     }
 663   }
 664
 665   if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
 666     return JPEG_ROW_COMPLETED;
 667   return JPEG_SCAN_COMPLETED;
 668 }
 669
 670 #endif /* BLOCK_SMOOTHING_SUPPORTED */
 671
 672
 673 /*
 674  * Initialize coefficient buffer controller.
 675  */
 676
 677 GLOBAL(void)
 678 jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
 679 {
 680   my_coef_ptr coef;
 681
 682   coef = (my_coef_ptr)
 683     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 684                                 SIZEOF(my_coef_controller));
 685   cinfo->coef = (struct jpeg_d_coef_controller *) coef;
 686   coef->pub.start_input_pass = start_input_pass;
 687   coef->pub.start_output_pass = start_output_pass;
 688 #ifdef BLOCK_SMOOTHING_SUPPORTED
 689   coef->coef_bits_latch = NULL;
 690 #endif
 691
 692   /* Create the coefficient buffer. */
 693   if (need_full_buffer) {
 694 #ifdef D_MULTISCAN_FILES_SUPPORTED
 695     /* Allocate a full-image virtual array for each component, */
 696     /* padded to a multiple of samp_factor DCT blocks in each direction. */
 697     /* Note we ask for a pre-zeroed array. */
 698     int ci, access_rows;
 699     jpeg_component_info *compptr;
 700
 701     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 702          ci++, compptr++) {
 703       access_rows = compptr->v_samp_factor;
 704 #ifdef BLOCK_SMOOTHING_SUPPORTED
 705       /* If block smoothing could be used, need a bigger window */
 706       if (cinfo->progressive_mode)
 707         access_rows *= 3;
 708 #endif
 709       coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
 710         ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
 711          (JDIMENSION) jround_up((long) compptr->width_in_blocks,
 712                                 (long) compptr->h_samp_factor),
 713          (JDIMENSION) jround_up((long) compptr->height_in_blocks,
 714                                 (long) compptr->v_samp_factor),
 715          (JDIMENSION) access_rows);
 716     }
 717     coef->pub.consume_data = consume_data;
 718     coef->pub.decompress_data = decompress_data;
 719     coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
 720 #else
 721     ERREXIT(cinfo, JERR_NOT_COMPILED);
 722 #endif
 723   } else {
 724     /* We only need a single-MCU buffer. */
 725     JBLOCKROW buffer;
 726     int i;
 727
 728     buffer = (JBLOCKROW)
 729       (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 730                                   D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
 731     for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) {
 732       coef->MCU_buffer[i] = buffer + i;
 733     }
 734     if (cinfo->lim_Se == 0)     /* DC only case: want to bypass later */
 735       FMEMZERO((void FAR *) buffer,
 736                (size_t) (D_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK)));
 737     coef->pub.consume_data = dummy_consume_data;
 738     coef->pub.decompress_data = decompress_onepass;
 739     coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */
 740   }
 741 }