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plt-scheme  4.2.1
jdmainct.c
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00001 /*
00002  * jdmainct.c
00003  *
00004  * Copyright (C) 1994-1996, Thomas G. Lane.
00005  * This file is part of the Independent JPEG Group's software.
00006  * For conditions of distribution and use, see the accompanying README file.
00007  *
00008  * This file contains the main buffer controller for decompression.
00009  * The main buffer lies between the JPEG decompressor proper and the
00010  * post-processor; it holds downsampled data in the JPEG colorspace.
00011  *
00012  * Note that this code is bypassed in raw-data mode, since the application
00013  * supplies the equivalent of the main buffer in that case.
00014  */
00015 
00016 #define JPEG_INTERNALS
00017 #include "jinclude.h"
00018 #include "jpeglib.h"
00019 
00020 
00021 /*
00022  * In the current system design, the main buffer need never be a full-image
00023  * buffer; any full-height buffers will be found inside the coefficient or
00024  * postprocessing controllers.  Nonetheless, the main controller is not
00025  * trivial.  Its responsibility is to provide context rows for upsampling/
00026  * rescaling, and doing this in an efficient fashion is a bit tricky.
00027  *
00028  * Postprocessor input data is counted in "row groups".  A row group
00029  * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
00030  * sample rows of each component.  (We require DCT_scaled_size values to be
00031  * chosen such that these numbers are integers.  In practice DCT_scaled_size
00032  * values will likely be powers of two, so we actually have the stronger
00033  * condition that DCT_scaled_size / min_DCT_scaled_size is an integer.)
00034  * Upsampling will typically produce max_v_samp_factor pixel rows from each
00035  * row group (times any additional scale factor that the upsampler is
00036  * applying).
00037  *
00038  * The coefficient controller will deliver data to us one iMCU row at a time;
00039  * each iMCU row contains v_samp_factor * DCT_scaled_size sample rows, or
00040  * exactly min_DCT_scaled_size row groups.  (This amount of data corresponds
00041  * to one row of MCUs when the image is fully interleaved.)  Note that the
00042  * number of sample rows varies across components, but the number of row
00043  * groups does not.  Some garbage sample rows may be included in the last iMCU
00044  * row at the bottom of the image.
00045  *
00046  * Depending on the vertical scaling algorithm used, the upsampler may need
00047  * access to the sample row(s) above and below its current input row group.
00048  * The upsampler is required to set need_context_rows TRUE at global selection
00049  * time if so.  When need_context_rows is FALSE, this controller can simply
00050  * obtain one iMCU row at a time from the coefficient controller and dole it
00051  * out as row groups to the postprocessor.
00052  *
00053  * When need_context_rows is TRUE, this controller guarantees that the buffer
00054  * passed to postprocessing contains at least one row group's worth of samples
00055  * above and below the row group(s) being processed.  Note that the context
00056  * rows "above" the first passed row group appear at negative row offsets in
00057  * the passed buffer.  At the top and bottom of the image, the required
00058  * context rows are manufactured by duplicating the first or last real sample
00059  * row; this avoids having special cases in the upsampling inner loops.
00060  *
00061  * The amount of context is fixed at one row group just because that's a
00062  * convenient number for this controller to work with.  The existing
00063  * upsamplers really only need one sample row of context.  An upsampler
00064  * supporting arbitrary output rescaling might wish for more than one row
00065  * group of context when shrinking the image; tough, we don't handle that.
00066  * (This is justified by the assumption that downsizing will be handled mostly
00067  * by adjusting the DCT_scaled_size values, so that the actual scale factor at
00068  * the upsample step needn't be much less than one.)
00069  *
00070  * To provide the desired context, we have to retain the last two row groups
00071  * of one iMCU row while reading in the next iMCU row.  (The last row group
00072  * can't be processed until we have another row group for its below-context,
00073  * and so we have to save the next-to-last group too for its above-context.)
00074  * We could do this most simply by copying data around in our buffer, but
00075  * that'd be very slow.  We can avoid copying any data by creating a rather
00076  * strange pointer structure.  Here's how it works.  We allocate a workspace
00077  * consisting of M+2 row groups (where M = min_DCT_scaled_size is the number
00078  * of row groups per iMCU row).  We create two sets of redundant pointers to
00079  * the workspace.  Labeling the physical row groups 0 to M+1, the synthesized
00080  * pointer lists look like this:
00081  *                   M+1                          M-1
00082  * master pointer --> 0         master pointer --> 0
00083  *                    1                            1
00084  *                   ...                          ...
00085  *                   M-3                          M-3
00086  *                   M-2                           M
00087  *                   M-1                          M+1
00088  *                    M                           M-2
00089  *                   M+1                          M-1
00090  *                    0                            0
00091  * We read alternate iMCU rows using each master pointer; thus the last two
00092  * row groups of the previous iMCU row remain un-overwritten in the workspace.
00093  * The pointer lists are set up so that the required context rows appear to
00094  * be adjacent to the proper places when we pass the pointer lists to the
00095  * upsampler.
00096  *
00097  * The above pictures describe the normal state of the pointer lists.
00098  * At top and bottom of the image, we diddle the pointer lists to duplicate
00099  * the first or last sample row as necessary (this is cheaper than copying
00100  * sample rows around).
00101  *
00102  * This scheme breaks down if M < 2, ie, min_DCT_scaled_size is 1.  In that
00103  * situation each iMCU row provides only one row group so the buffering logic
00104  * must be different (eg, we must read two iMCU rows before we can emit the
00105  * first row group).  For now, we simply do not support providing context
00106  * rows when min_DCT_scaled_size is 1.  That combination seems unlikely to
00107  * be worth providing --- if someone wants a 1/8th-size preview, they probably
00108  * want it quick and dirty, so a context-free upsampler is sufficient.
00109  */
00110 
00111 
00112 /* Private buffer controller object */
00113 
00114 typedef struct {
00115   struct jpeg_d_main_controller pub; /* public fields */
00116 
00117   /* Pointer to allocated workspace (M or M+2 row groups). */
00118   JSAMPARRAY buffer[MAX_COMPONENTS];
00119 
00120   boolean buffer_full;             /* Have we gotten an iMCU row from decoder? */
00121   JDIMENSION rowgroup_ctr;  /* counts row groups output to postprocessor */
00122 
00123   /* Remaining fields are only used in the context case. */
00124 
00125   /* These are the master pointers to the funny-order pointer lists. */
00126   JSAMPIMAGE xbuffer[2];    /* pointers to weird pointer lists */
00127 
00128   int whichptr;                    /* indicates which pointer set is now in use */
00129   int context_state;        /* process_data state machine status */
00130   JDIMENSION rowgroups_avail;      /* row groups available to postprocessor */
00131   JDIMENSION iMCU_row_ctr;  /* counts iMCU rows to detect image top/bot */
00132 } my_main_controller;
00133 
00134 typedef my_main_controller * my_main_ptr;
00135 
00136 /* context_state values: */
00137 #define CTX_PREPARE_FOR_IMCU       0      /* need to prepare for MCU row */
00138 #define CTX_PROCESS_IMCU    1      /* feeding iMCU to postprocessor */
00139 #define CTX_POSTPONED_ROW   2      /* feeding postponed row group */
00140 
00141 
00142 /* Forward declarations */
00143 METHODDEF(void) process_data_simple_main
00144        JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf,
00145             JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail));
00146 METHODDEF(void) process_data_context_main
00147        JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf,
00148             JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail));
00149 #ifdef QUANT_2PASS_SUPPORTED
00150 METHODDEF(void) process_data_crank_post
00151        JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf,
00152             JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail));
00153 #endif
00154 
00155 
00156 LOCAL(void)
00157 alloc_funny_pointers (j_decompress_ptr cinfo)
00158 /* Allocate space for the funny pointer lists.
00159  * This is done only once, not once per pass.
00160  */
00161 {
00162   my_main_ptr main = (my_main_ptr) cinfo->main;
00163   int ci, rgroup;
00164   int M = cinfo->min_DCT_scaled_size;
00165   jpeg_component_info *compptr;
00166   JSAMPARRAY xbuf;
00167 
00168   /* Get top-level space for component array pointers.
00169    * We alloc both arrays with one call to save a few cycles.
00170    */
00171   main->xbuffer[0] = (JSAMPIMAGE)
00172     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
00173                             cinfo->num_components * 2 * SIZEOF(JSAMPARRAY));
00174   main->xbuffer[1] = main->xbuffer[0] + cinfo->num_components;
00175 
00176   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
00177        ci++, compptr++) {
00178     rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
00179       cinfo->min_DCT_scaled_size; /* height of a row group of component */
00180     /* Get space for pointer lists --- M+4 row groups in each list.
00181      * We alloc both pointer lists with one call to save a few cycles.
00182      */
00183     xbuf = (JSAMPARRAY)
00184       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
00185                               2 * (rgroup * (M + 4)) * SIZEOF(JSAMPROW));
00186     xbuf += rgroup;         /* want one row group at negative offsets */
00187     main->xbuffer[0][ci] = xbuf;
00188     xbuf += rgroup * (M + 4);
00189     main->xbuffer[1][ci] = xbuf;
00190   }
00191 }
00192 
00193 
00194 LOCAL(void)
00195 make_funny_pointers (j_decompress_ptr cinfo)
00196 /* Create the funny pointer lists discussed in the comments above.
00197  * The actual workspace is already allocated (in main->buffer),
00198  * and the space for the pointer lists is allocated too.
00199  * This routine just fills in the curiously ordered lists.
00200  * This will be repeated at the beginning of each pass.
00201  */
00202 {
00203   my_main_ptr main = (my_main_ptr) cinfo->main;
00204   int ci, i, rgroup;
00205   int M = cinfo->min_DCT_scaled_size;
00206   jpeg_component_info *compptr;
00207   JSAMPARRAY buf, xbuf0, xbuf1;
00208 
00209   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
00210        ci++, compptr++) {
00211     rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
00212       cinfo->min_DCT_scaled_size; /* height of a row group of component */
00213     xbuf0 = main->xbuffer[0][ci];
00214     xbuf1 = main->xbuffer[1][ci];
00215     /* First copy the workspace pointers as-is */
00216     buf = main->buffer[ci];
00217     for (i = 0; i < rgroup * (M + 2); i++) {
00218       xbuf0[i] = xbuf1[i] = buf[i];
00219     }
00220     /* In the second list, put the last four row groups in swapped order */
00221     for (i = 0; i < rgroup * 2; i++) {
00222       xbuf1[rgroup*(M-2) + i] = buf[rgroup*M + i];
00223       xbuf1[rgroup*M + i] = buf[rgroup*(M-2) + i];
00224     }
00225     /* The wraparound pointers at top and bottom will be filled later
00226      * (see set_wraparound_pointers, below).  Initially we want the "above"
00227      * pointers to duplicate the first actual data line.  This only needs
00228      * to happen in xbuffer[0].
00229      */
00230     for (i = 0; i < rgroup; i++) {
00231       xbuf0[i - rgroup] = xbuf0[0];
00232     }
00233   }
00234 }
00235 
00236 
00237 LOCAL(void)
00238 set_wraparound_pointers (j_decompress_ptr cinfo)
00239 /* Set up the "wraparound" pointers at top and bottom of the pointer lists.
00240  * This changes the pointer list state from top-of-image to the normal state.
00241  */
00242 {
00243   my_main_ptr main = (my_main_ptr) cinfo->main;
00244   int ci, i, rgroup;
00245   int M = cinfo->min_DCT_scaled_size;
00246   jpeg_component_info *compptr;
00247   JSAMPARRAY xbuf0, xbuf1;
00248 
00249   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
00250        ci++, compptr++) {
00251     rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
00252       cinfo->min_DCT_scaled_size; /* height of a row group of component */
00253     xbuf0 = main->xbuffer[0][ci];
00254     xbuf1 = main->xbuffer[1][ci];
00255     for (i = 0; i < rgroup; i++) {
00256       xbuf0[i - rgroup] = xbuf0[rgroup*(M+1) + i];
00257       xbuf1[i - rgroup] = xbuf1[rgroup*(M+1) + i];
00258       xbuf0[rgroup*(M+2) + i] = xbuf0[i];
00259       xbuf1[rgroup*(M+2) + i] = xbuf1[i];
00260     }
00261   }
00262 }
00263 
00264 
00265 LOCAL(void)
00266 set_bottom_pointers (j_decompress_ptr cinfo)
00267 /* Change the pointer lists to duplicate the last sample row at the bottom
00268  * of the image.  whichptr indicates which xbuffer holds the final iMCU row.
00269  * Also sets rowgroups_avail to indicate number of nondummy row groups in row.
00270  */
00271 {
00272   my_main_ptr main = (my_main_ptr) cinfo->main;
00273   int ci, i, rgroup, iMCUheight, rows_left;
00274   jpeg_component_info *compptr;
00275   JSAMPARRAY xbuf;
00276 
00277   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
00278        ci++, compptr++) {
00279     /* Count sample rows in one iMCU row and in one row group */
00280     iMCUheight = compptr->v_samp_factor * compptr->DCT_scaled_size;
00281     rgroup = iMCUheight / cinfo->min_DCT_scaled_size;
00282     /* Count nondummy sample rows remaining for this component */
00283     rows_left = (int) (compptr->downsampled_height % (JDIMENSION) iMCUheight);
00284     if (rows_left == 0) rows_left = iMCUheight;
00285     /* Count nondummy row groups.  Should get same answer for each component,
00286      * so we need only do it once.
00287      */
00288     if (ci == 0) {
00289       main->rowgroups_avail = (JDIMENSION) ((rows_left-1) / rgroup + 1);
00290     }
00291     /* Duplicate the last real sample row rgroup*2 times; this pads out the
00292      * last partial rowgroup and ensures at least one full rowgroup of context.
00293      */
00294     xbuf = main->xbuffer[main->whichptr][ci];
00295     for (i = 0; i < rgroup * 2; i++) {
00296       xbuf[rows_left + i] = xbuf[rows_left-1];
00297     }
00298   }
00299 }
00300 
00301 
00302 /*
00303  * Initialize for a processing pass.
00304  */
00305 
00306 METHODDEF(void)
00307 start_pass_main (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
00308 {
00309   my_main_ptr main = (my_main_ptr) cinfo->main;
00310 
00311   switch (pass_mode) {
00312   case JBUF_PASS_THRU:
00313     if (cinfo->upsample->need_context_rows) {
00314       main->pub.process_data = process_data_context_main;
00315       make_funny_pointers(cinfo); /* Create the xbuffer[] lists */
00316       main->whichptr = 0;   /* Read first iMCU row into xbuffer[0] */
00317       main->context_state = CTX_PREPARE_FOR_IMCU;
00318       main->iMCU_row_ctr = 0;
00319     } else {
00320       /* Simple case with no context needed */
00321       main->pub.process_data = process_data_simple_main;
00322     }
00323     main->buffer_full = FALSE;     /* Mark buffer empty */
00324     main->rowgroup_ctr = 0;
00325     break;
00326 #ifdef QUANT_2PASS_SUPPORTED
00327   case JBUF_CRANK_DEST:
00328     /* For last pass of 2-pass quantization, just crank the postprocessor */
00329     main->pub.process_data = process_data_crank_post;
00330     break;
00331 #endif
00332   default:
00333     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
00334     break;
00335   }
00336 }
00337 
00338 
00339 /*
00340  * Process some data.
00341  * This handles the simple case where no context is required.
00342  */
00343 
00344 METHODDEF(void)
00345 process_data_simple_main (j_decompress_ptr cinfo,
00346                        JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
00347                        JDIMENSION out_rows_avail)
00348 {
00349   my_main_ptr main = (my_main_ptr) cinfo->main;
00350   JDIMENSION rowgroups_avail;
00351 
00352   /* Read input data if we haven't filled the main buffer yet */
00353   if (! main->buffer_full) {
00354     if (! (*cinfo->coef->decompress_data) (cinfo, main->buffer))
00355       return;               /* suspension forced, can do nothing more */
00356     main->buffer_full = TRUE;      /* OK, we have an iMCU row to work with */
00357   }
00358 
00359   /* There are always min_DCT_scaled_size row groups in an iMCU row. */
00360   rowgroups_avail = (JDIMENSION) cinfo->min_DCT_scaled_size;
00361   /* Note: at the bottom of the image, we may pass extra garbage row groups
00362    * to the postprocessor.  The postprocessor has to check for bottom
00363    * of image anyway (at row resolution), so no point in us doing it too.
00364    */
00365 
00366   /* Feed the postprocessor */
00367   (*cinfo->post->post_process_data) (cinfo, main->buffer,
00368                                  &main->rowgroup_ctr, rowgroups_avail,
00369                                  output_buf, out_row_ctr, out_rows_avail);
00370 
00371   /* Has postprocessor consumed all the data yet? If so, mark buffer empty */
00372   if (main->rowgroup_ctr >= rowgroups_avail) {
00373     main->buffer_full = FALSE;
00374     main->rowgroup_ctr = 0;
00375   }
00376 }
00377 
00378 
00379 /*
00380  * Process some data.
00381  * This handles the case where context rows must be provided.
00382  */
00383 
00384 METHODDEF(void)
00385 process_data_context_main (j_decompress_ptr cinfo,
00386                         JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
00387                         JDIMENSION out_rows_avail)
00388 {
00389   my_main_ptr main = (my_main_ptr) cinfo->main;
00390 
00391   /* Read input data if we haven't filled the main buffer yet */
00392   if (! main->buffer_full) {
00393     if (! (*cinfo->coef->decompress_data) (cinfo,
00394                                       main->xbuffer[main->whichptr]))
00395       return;               /* suspension forced, can do nothing more */
00396     main->buffer_full = TRUE;      /* OK, we have an iMCU row to work with */
00397     main->iMCU_row_ctr++;   /* count rows received */
00398   }
00399 
00400   /* Postprocessor typically will not swallow all the input data it is handed
00401    * in one call (due to filling the output buffer first).  Must be prepared
00402    * to exit and restart.  This switch lets us keep track of how far we got.
00403    * Note that each case falls through to the next on successful completion.
00404    */
00405   switch (main->context_state) {
00406   case CTX_POSTPONED_ROW:
00407     /* Call postprocessor using previously set pointers for postponed row */
00408     (*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr],
00409                      &main->rowgroup_ctr, main->rowgroups_avail,
00410                      output_buf, out_row_ctr, out_rows_avail);
00411     if (main->rowgroup_ctr < main->rowgroups_avail)
00412       return;               /* Need to suspend */
00413     main->context_state = CTX_PREPARE_FOR_IMCU;
00414     if (*out_row_ctr >= out_rows_avail)
00415       return;               /* Postprocessor exactly filled output buf */
00416     /*FALLTHROUGH*/
00417   case CTX_PREPARE_FOR_IMCU:
00418     /* Prepare to process first M-1 row groups of this iMCU row */
00419     main->rowgroup_ctr = 0;
00420     main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_scaled_size - 1);
00421     /* Check for bottom of image: if so, tweak pointers to "duplicate"
00422      * the last sample row, and adjust rowgroups_avail to ignore padding rows.
00423      */
00424     if (main->iMCU_row_ctr == cinfo->total_iMCU_rows)
00425       set_bottom_pointers(cinfo);
00426     main->context_state = CTX_PROCESS_IMCU;
00427     /*FALLTHROUGH*/
00428   case CTX_PROCESS_IMCU:
00429     /* Call postprocessor using previously set pointers */
00430     (*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr],
00431                      &main->rowgroup_ctr, main->rowgroups_avail,
00432                      output_buf, out_row_ctr, out_rows_avail);
00433     if (main->rowgroup_ctr < main->rowgroups_avail)
00434       return;               /* Need to suspend */
00435     /* After the first iMCU, change wraparound pointers to normal state */
00436     if (main->iMCU_row_ctr == 1)
00437       set_wraparound_pointers(cinfo);
00438     /* Prepare to load new iMCU row using other xbuffer list */
00439     main->whichptr ^= 1;    /* 0=>1 or 1=>0 */
00440     main->buffer_full = FALSE;
00441     /* Still need to process last row group of this iMCU row, */
00442     /* which is saved at index M+1 of the other xbuffer */
00443     main->rowgroup_ctr = (JDIMENSION) (cinfo->min_DCT_scaled_size + 1);
00444     main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_scaled_size + 2);
00445     main->context_state = CTX_POSTPONED_ROW;
00446   }
00447 }
00448 
00449 
00450 /*
00451  * Process some data.
00452  * Final pass of two-pass quantization: just call the postprocessor.
00453  * Source data will be the postprocessor controller's internal buffer.
00454  */
00455 
00456 #ifdef QUANT_2PASS_SUPPORTED
00457 
00458 METHODDEF(void)
00459 process_data_crank_post (j_decompress_ptr cinfo,
00460                       JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
00461                       JDIMENSION out_rows_avail)
00462 {
00463   (*cinfo->post->post_process_data) (cinfo, (JSAMPIMAGE) NULL,
00464                                  (JDIMENSION *) NULL, (JDIMENSION) 0,
00465                                  output_buf, out_row_ctr, out_rows_avail);
00466 }
00467 
00468 #endif /* QUANT_2PASS_SUPPORTED */
00469 
00470 
00471 /*
00472  * Initialize main buffer controller.
00473  */
00474 
00475 GLOBAL(void)
00476 jinit_d_main_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
00477 {
00478   my_main_ptr main;
00479   int ci, rgroup, ngroups;
00480   jpeg_component_info *compptr;
00481 
00482   main = (my_main_ptr)
00483     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
00484                             SIZEOF(my_main_controller));
00485   cinfo->main = (struct jpeg_d_main_controller *) main;
00486   main->pub.start_pass = start_pass_main;
00487 
00488   if (need_full_buffer)            /* shouldn't happen */
00489     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
00490 
00491   /* Allocate the workspace.
00492    * ngroups is the number of row groups we need.
00493    */
00494   if (cinfo->upsample->need_context_rows) {
00495     if (cinfo->min_DCT_scaled_size < 2) /* unsupported, see comments above */
00496       ERREXIT(cinfo, JERR_NOTIMPL);
00497     alloc_funny_pointers(cinfo); /* Alloc space for xbuffer[] lists */
00498     ngroups = cinfo->min_DCT_scaled_size + 2;
00499   } else {
00500     ngroups = cinfo->min_DCT_scaled_size;
00501   }
00502 
00503   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
00504        ci++, compptr++) {
00505     rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
00506       cinfo->min_DCT_scaled_size; /* height of a row group of component */
00507     main->buffer[ci] = (*cinfo->mem->alloc_sarray)
00508                      ((j_common_ptr) cinfo, JPOOL_IMAGE,
00509                       compptr->width_in_blocks * compptr->DCT_scaled_size,
00510                       (JDIMENSION) (rgroup * ngroups));
00511   }
00512 }