compiler/libjpeg/main/jcmainct.c

   1 /*
   2     $Id$
   3 */
   4
   5 /*
   6  * jcmainct.c
   7  *
   8  * Copyright (C) 1994-1998, Thomas G. Lane.
   9  * This file is part of the Independent JPEG Group's software.
  10  * For conditions of distribution and use, see the accompanying README file.
  11  *
  12  * This file contains the main buffer controller for compression.
  13  * The main buffer lies between the pre-processor and the JPEG
  14  * compressor proper; it holds downsampled data in the JPEG colorspace.
  15  */
  16
  17 #define JPEG_INTERNALS
  18 #include "jinclude.h"
  19 #include "jpeglib.h"
  20
  21
  22 /* Note: currently, there is no operating mode in which a full-image buffer
  23  * is needed at this step.  If there were, that mode could not be used with
  24  * "raw data" input, since this module is bypassed in that case.  However,
  25  * we've left the code here for possible use in special applications.
  26  */
  27 #undef FULL_MAIN_BUFFER_SUPPORTED
  28
  29
  30 /* Private buffer controller object */
  31
  32 typedef struct {
  33   struct jpeg_c_main_controller pub; /* public fields */
  34
  35   JDIMENSION cur_iMCU_row;      /* number of current iMCU row */
  36   JDIMENSION rowgroup_ctr;      /* counts row groups received in iMCU row */
  37   boolean suspended;            /* remember if we suspended output */
  38   J_BUF_MODE pass_mode;         /* current operating mode */
  39
  40   /* If using just a strip buffer, this points to the entire set of buffers
  41    * (we allocate one for each component).  In the full-image case, this
  42    * points to the currently accessible strips of the virtual arrays.
  43    */
  44   JSAMPARRAY buffer[MAX_COMPONENTS];
  45
  46 #ifdef FULL_MAIN_BUFFER_SUPPORTED
  47   /* If using full-image storage, this array holds pointers to virtual-array
  48    * control blocks for each component.  Unused if not full-image storage.
  49    */
  50   jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
  51 #endif
  52 } my_main_controller;
  53
  54 typedef my_main_controller * my_main_ptr;
  55
  56
  57 /* Forward declarations */
  58 METHODDEF(void) process_data_simple_main
  59         JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
  60              JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
  61 #ifdef FULL_MAIN_BUFFER_SUPPORTED
  62 METHODDEF(void) process_data_buffer_main
  63         JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
  64              JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
  65 #endif
  66
  67
  68 /*
  69  * Initialize for a processing pass.
  70  */
  71
  72 METHODDEF(void)
  73 start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
  74 {
  75   my_main_ptr main = (my_main_ptr) cinfo->main;
  76
  77   /* Do nothing in raw-data mode. */
  78   if (cinfo->raw_data_in)
  79     return;
  80
  81   main->cur_iMCU_row = 0;       /* initialize counters */
  82   main->rowgroup_ctr = 0;
  83   main->suspended = FALSE;
  84   main->pass_mode = pass_mode;  /* save mode for use by process_data */
  85
  86   switch (pass_mode) {
  87   case JBUF_PASS_THRU:
  88 #ifdef FULL_MAIN_BUFFER_SUPPORTED
  89     if (main->whole_image[0] != NULL)
  90       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
  91 #endif
  92     main->pub.process_data = process_data_simple_main;
  93     break;
  94 #ifdef FULL_MAIN_BUFFER_SUPPORTED
  95   case JBUF_SAVE_SOURCE:
  96   case JBUF_CRANK_DEST:
  97   case JBUF_SAVE_AND_PASS:
  98     if (main->whole_image[0] == NULL)
  99       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
 100     main->pub.process_data = process_data_buffer_main;
 101     break;
 102 #endif
 103   default:
 104     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
 105     break;
 106   }
 107 }
 108
 109
 110 /*
 111  * Process some data.
 112  * This routine handles the simple pass-through mode,
 113  * where we have only a strip buffer.
 114  */
 115
 116 METHODDEF(void)
 117 process_data_simple_main (j_compress_ptr cinfo,
 118                           JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
 119                           JDIMENSION in_rows_avail)
 120 {
 121   my_main_ptr main = (my_main_ptr) cinfo->main;
 122   int data_unit = cinfo->data_unit;
 123
 124   while (main->cur_iMCU_row < cinfo->total_iMCU_rows) {
 125     /* Read input data if we haven't filled the main buffer yet */
 126     if (main->rowgroup_ctr < data_unit)
 127       (*cinfo->prep->pre_process_data) (cinfo,
 128                                         input_buf, in_row_ctr, in_rows_avail,
 129                                         main->buffer, &main->rowgroup_ctr,
 130                                         (JDIMENSION) data_unit);
 131
 132     /* If we don't have a full iMCU row buffered, return to application for
 133      * more data.  Note that preprocessor will always pad to fill the iMCU row
 134      * at the bottom of the image.
 135      */
 136     if (main->rowgroup_ctr != data_unit)
 137       return;
 138
 139     /* Send the completed row to the compressor */
 140     if (! (*cinfo->codec->compress_data) (cinfo, main->buffer)) {
 141       /* If compressor did not consume the whole row, then we must need to
 142        * suspend processing and return to the application.  In this situation
 143        * we pretend we didn't yet consume the last input row; otherwise, if
 144        * it happened to be the last row of the image, the application would
 145        * think we were done.
 146        */
 147       if (! main->suspended) {
 148         (*in_row_ctr)--;
 149         main->suspended = TRUE;
 150       }
 151       return;
 152     }
 153     /* We did finish the row.  Undo our little suspension hack if a previous
 154      * call suspended; then mark the main buffer empty.
 155      */
 156     if (main->suspended) {
 157       (*in_row_ctr)++;
 158       main->suspended = FALSE;
 159     }
 160     main->rowgroup_ctr = 0;
 161     main->cur_iMCU_row++;
 162   }
 163 }
 164
 165
 166 #ifdef FULL_MAIN_BUFFER_SUPPORTED
 167
 168 /*
 169  * Process some data.
 170  * This routine handles all of the modes that use a full-size buffer.
 171  */
 172
 173 METHODDEF(void)
 174 process_data_buffer_main (j_compress_ptr cinfo,
 175                           JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
 176                           JDIMENSION in_rows_avail)
 177 {
 178   my_main_ptr main = (my_main_ptr) cinfo->main;
 179   int ci;
 180   jpeg_component_info *compptr;
 181   boolean writing = (main->pass_mode != JBUF_CRANK_DEST);
 182   int data_unit = cinfo->data_unit;
 183
 184   while (main->cur_iMCU_row < cinfo->total_iMCU_rows) {
 185     /* Realign the virtual buffers if at the start of an iMCU row. */
 186     if (main->rowgroup_ctr == 0) {
 187       for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 188            ci++, compptr++) {
 189         main->buffer[ci] = (*cinfo->mem->access_virt_sarray)
 190           ((j_common_ptr) cinfo, main->whole_image[ci],
 191            main->cur_iMCU_row * (compptr->v_samp_factor * data_unit),
 192            (JDIMENSION) (compptr->v_samp_factor * data_unit), writing);
 193       }
 194       /* In a read pass, pretend we just read some source data. */
 195       if (! writing) {
 196         *in_row_ctr += cinfo->max_v_samp_factor * data_unit;
 197         main->rowgroup_ctr = data_unit;
 198       }
 199     }
 200
 201     /* If a write pass, read input data until the current iMCU row is full. */
 202     /* Note: preprocessor will pad if necessary to fill the last iMCU row. */
 203     if (writing) {
 204       (*cinfo->prep->pre_process_data) (cinfo,
 205                                         input_buf, in_row_ctr, in_rows_avail,
 206                                         main->buffer, &main->rowgroup_ctr,
 207                                         (JDIMENSION) data_unit);
 208       /* Return to application if we need more data to fill the iMCU row. */
 209       if (main->rowgroup_ctr < data_unit)
 210         return;
 211     }
 212
 213     /* Emit data, unless this is a sink-only pass. */
 214     if (main->pass_mode != JBUF_SAVE_SOURCE) {
 215       if (! (*cinfo->codec->compress_data) (cinfo, main->buffer)) {
 216         /* If compressor did not consume the whole row, then we must need to
 217          * suspend processing and return to the application.  In this situation
 218          * we pretend we didn't yet consume the last input row; otherwise, if
 219          * it happened to be the last row of the image, the application would
 220          * think we were done.
 221          */
 222         if (! main->suspended) {
 223           (*in_row_ctr)--;
 224           main->suspended = TRUE;
 225         }
 226         return;
 227       }
 228       /* We did finish the row.  Undo our little suspension hack if a previous
 229        * call suspended; then mark the main buffer empty.
 230        */
 231       if (main->suspended) {
 232         (*in_row_ctr)++;
 233         main->suspended = FALSE;
 234       }
 235     }
 236
 237     /* If get here, we are done with this iMCU row.  Mark buffer empty. */
 238     main->rowgroup_ctr = 0;
 239     main->cur_iMCU_row++;
 240   }
 241 }
 242
 243 #endif /* FULL_MAIN_BUFFER_SUPPORTED */
 244
 245
 246 /*
 247  * Initialize main buffer controller.
 248  */
 249
 250 JGLOBAL(void)
 251 jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
 252 {
 253   my_main_ptr main;
 254   int ci;
 255   jpeg_component_info *compptr;
 256   int data_unit = cinfo->data_unit;
 257
 258   main = (my_main_ptr)
 259     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 260                                 SIZEOF(my_main_controller));
 261   cinfo->main = (struct jpeg_c_main_controller *) main;
 262   main->pub.start_pass = start_pass_main;
 263
 264   /* We don't need to create a buffer in raw-data mode. */
 265   if (cinfo->raw_data_in)
 266     return;
 267
 268   /* Create the buffer.  It holds downsampled data, so each component
 269    * may be of a different size.
 270    */
 271   if (need_full_buffer) {
 272 #ifdef FULL_MAIN_BUFFER_SUPPORTED
 273     /* Allocate a full-image virtual array for each component */
 274     /* Note we pad the bottom to a multiple of the iMCU height */
 275     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 276          ci++, compptr++) {
 277       main->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
 278         ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
 279          compptr->width_in_data_units * data_unit,
 280          (JDIMENSION) jround_up((long) compptr->height_in_data_units,
 281                                 (long) compptr->v_samp_factor) * data_unit,
 282          (JDIMENSION) (compptr->v_samp_factor * data_unit));
 283     }
 284 #else
 285     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
 286 #endif
 287   } else {
 288 #ifdef FULL_MAIN_BUFFER_SUPPORTED
 289     main->whole_image[0] = NULL; /* flag for no virtual arrays */
 290 #endif
 291     /* Allocate a strip buffer for each component */
 292     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 293          ci++, compptr++) {
 294       main->buffer[ci] = (*cinfo->mem->alloc_sarray)
 295         ((j_common_ptr) cinfo, JPOOL_IMAGE,
 296          compptr->width_in_data_units * data_unit,
 297          (JDIMENSION) (compptr->v_samp_factor * data_unit));
 298     }
 299   }
 300 }