00001 /*
00002  * jcmainct.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 compression.
00009  * The main buffer lies between the pre-processor and the JPEG
00010  * compressor proper; it holds downsampled data in the JPEG colorspace.
00011  */
00012 
00013 #define JPEG_INTERNALS
00014 #include "jinclude.h"
00015 #include "jpeglib.h"
00016 
00017 
00018 /* Note: currently, there is no operating mode in which a full-image buffer
00019  * is needed at this step.  If there were, that mode could not be used with
00020  * "raw data" input, since this module is bypassed in that case.  However,
00021  * we've left the code here for possible use in special applications.
00022  */
00023 #undef FULL_MAIN_BUFFER_SUPPORTED
00024 
00025 
00026 /* Private buffer controller object */
00027 
00028 typedef struct {
00029   struct jpeg_c_main_controller pub; /* public fields */
00030 
00031   JDIMENSION cur_iMCU_row;      /* number of current iMCU row */
00032   JDIMENSION rowgroup_ctr;      /* counts row groups received in iMCU row */
00033   boolean suspended;            /* remember if we suspended output */
00034   J_BUF_MODE pass_mode;         /* current operating mode */
00035 
00036   /* If using just a strip buffer, this points to the entire set of buffers
00037    * (we allocate one for each component).  In the full-image case, this
00038    * points to the currently accessible strips of the virtual arrays.
00039    */
00040   JSAMPARRAY buffer[MAX_COMPONENTS];
00041 
00042 #ifdef FULL_MAIN_BUFFER_SUPPORTED
00043   /* If using full-image storage, this array holds pointers to virtual-array
00044    * control blocks for each component.  Unused if not full-image storage.
00045    */
00046   jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
00047 #endif
00048 } my_main_controller;
00049 
00050 typedef my_main_controller * my_main_ptr;
00051 
00052 
00053 /* Forward declarations */
00054 METHODDEF(void) process_data_simple_main
00055         JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
00056              JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
00057 #ifdef FULL_MAIN_BUFFER_SUPPORTED
00058 METHODDEF(void) process_data_buffer_main
00059         JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
00060              JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
00061 #endif
00062 
00063 
00064 /*
00065  * Initialize for a processing pass.
00066  */
00067 
00068 METHODDEF(void)
00069 start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
00070 {
00071   my_main_ptr main = (my_main_ptr) cinfo->main;
00072 
00073   /* Do nothing in raw-data mode. */
00074   if (cinfo->raw_data_in)
00075     return;
00076 
00077   main->cur_iMCU_row = 0;       /* initialize counters */
00078   main->rowgroup_ctr = 0;
00079   main->suspended = FALSE;
00080   main->pass_mode = pass_mode;  /* save mode for use by process_data */
00081 
00082   switch (pass_mode) {
00083   case JBUF_PASS_THRU:
00084 #ifdef FULL_MAIN_BUFFER_SUPPORTED
00085     if (main->whole_image[0] != NULL)
00086       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
00087 #endif
00088     main->pub.process_data = process_data_simple_main;
00089     break;
00090 #ifdef FULL_MAIN_BUFFER_SUPPORTED
00091   case JBUF_SAVE_SOURCE:
00092   case JBUF_CRANK_DEST:
00093   case JBUF_SAVE_AND_PASS:
00094     if (main->whole_image[0] == NULL)
00095       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
00096     main->pub.process_data = process_data_buffer_main;
00097     break;
00098 #endif
00099   default:
00100     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
00101     break;
00102   }
00103 }
00104 
00105 
00106 /*
00107  * Process some data.
00108  * This routine handles the simple pass-through mode,
00109  * where we have only a strip buffer.
00110  */
00111 
00112 METHODDEF(void)
00113 process_data_simple_main (j_compress_ptr cinfo,
00114                           JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
00115                           JDIMENSION in_rows_avail)
00116 {
00117   my_main_ptr main = (my_main_ptr) cinfo->main;
00118 
00119   while (main->cur_iMCU_row < cinfo->total_iMCU_rows) {
00120     /* Read input data if we haven't filled the main buffer yet */
00121     if (main->rowgroup_ctr < DCTSIZE)
00122       (*cinfo->prep->pre_process_data) (cinfo,
00123                                         input_buf, in_row_ctr, in_rows_avail,
00124                                         main->buffer, &main->rowgroup_ctr,
00125                                         (JDIMENSION) DCTSIZE);
00126 
00127     /* If we don't have a full iMCU row buffered, return to application for
00128      * more data.  Note that preprocessor will always pad to fill the iMCU row
00129      * at the bottom of the image.
00130      */
00131     if (main->rowgroup_ctr != DCTSIZE)
00132       return;
00133 
00134     /* Send the completed row to the compressor */
00135     if (! (*cinfo->coef->compress_data) (cinfo, main->buffer)) {
00136       /* If compressor did not consume the whole row, then we must need to
00137        * suspend processing and return to the application.  In this situation
00138        * we pretend we didn't yet consume the last input row; otherwise, if
00139        * it happened to be the last row of the image, the application would
00140        * think we were done.
00141        */
00142       if (! main->suspended) {
00143         (*in_row_ctr)--;
00144         main->suspended = TRUE;
00145       }
00146       return;
00147     }
00148     /* We did finish the row.  Undo our little suspension hack if a previous
00149      * call suspended; then mark the main buffer empty.
00150      */
00151     if (main->suspended) {
00152       (*in_row_ctr)++;
00153       main->suspended = FALSE;
00154     }
00155     main->rowgroup_ctr = 0;
00156     main->cur_iMCU_row++;
00157   }
00158 }
00159 
00160 
00161 #ifdef FULL_MAIN_BUFFER_SUPPORTED
00162 
00163 /*
00164  * Process some data.
00165  * This routine handles all of the modes that use a full-size buffer.
00166  */
00167 
00168 METHODDEF(void)
00169 process_data_buffer_main (j_compress_ptr cinfo,
00170                           JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
00171                           JDIMENSION in_rows_avail)
00172 {
00173   my_main_ptr main = (my_main_ptr) cinfo->main;
00174   int ci;
00175   jpeg_component_info *compptr;
00176   boolean writing = (main->pass_mode != JBUF_CRANK_DEST);
00177 
00178   while (main->cur_iMCU_row < cinfo->total_iMCU_rows) {
00179     /* Realign the virtual buffers if at the start of an iMCU row. */
00180     if (main->rowgroup_ctr == 0) {
00181       for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
00182            ci++, compptr++) {
00183         main->buffer[ci] = (*cinfo->mem->access_virt_sarray)
00184           ((j_common_ptr) cinfo, main->whole_image[ci],
00185            main->cur_iMCU_row * (compptr->v_samp_factor * DCTSIZE),
00186            (JDIMENSION) (compptr->v_samp_factor * DCTSIZE), writing);
00187       }
00188       /* In a read pass, pretend we just read some source data. */
00189       if (! writing) {
00190         *in_row_ctr += cinfo->max_v_samp_factor * DCTSIZE;
00191         main->rowgroup_ctr = DCTSIZE;
00192       }
00193     }
00194 
00195     /* If a write pass, read input data until the current iMCU row is full. */
00196     /* Note: preprocessor will pad if necessary to fill the last iMCU row. */
00197     if (writing) {
00198       (*cinfo->prep->pre_process_data) (cinfo,
00199                                         input_buf, in_row_ctr, in_rows_avail,
00200                                         main->buffer, &main->rowgroup_ctr,
00201                                         (JDIMENSION) DCTSIZE);
00202       /* Return to application if we need more data to fill the iMCU row. */
00203       if (main->rowgroup_ctr < DCTSIZE)
00204         return;
00205     }
00206 
00207     /* Emit data, unless this is a sink-only pass. */
00208     if (main->pass_mode != JBUF_SAVE_SOURCE) {
00209       if (! (*cinfo->coef->compress_data) (cinfo, main->buffer)) {
00210         /* If compressor did not consume the whole row, then we must need to
00211          * suspend processing and return to the application.  In this situation
00212          * we pretend we didn't yet consume the last input row; otherwise, if
00213          * it happened to be the last row of the image, the application would
00214          * think we were done.
00215          */
00216         if (! main->suspended) {
00217           (*in_row_ctr)--;
00218           main->suspended = TRUE;
00219         }
00220         return;
00221       }
00222       /* We did finish the row.  Undo our little suspension hack if a previous
00223        * call suspended; then mark the main buffer empty.
00224        */
00225       if (main->suspended) {
00226         (*in_row_ctr)++;
00227         main->suspended = FALSE;
00228       }
00229     }
00230 
00231     /* If get here, we are done with this iMCU row.  Mark buffer empty. */
00232     main->rowgroup_ctr = 0;
00233     main->cur_iMCU_row++;
00234   }
00235 }
00236 
00237 #endif /* FULL_MAIN_BUFFER_SUPPORTED */
00238 
00239 
00240 /*
00241  * Initialize main buffer controller.
00242  */
00243 
00244 GLOBAL(void)
00245 jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
00246 {
00247   my_main_ptr main;
00248   int ci;
00249   jpeg_component_info *compptr;
00250 
00251   main = (my_main_ptr)
00252     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
00253                                 SIZEOF(my_main_controller));
00254   cinfo->main = (struct jpeg_c_main_controller *) main;
00255   main->pub.start_pass = start_pass_main;
00256 
00257   /* We don't need to create a buffer in raw-data mode. */
00258   if (cinfo->raw_data_in)
00259     return;
00260 
00261   /* Create the buffer.  It holds downsampled data, so each component
00262    * may be of a different size.
00263    */
00264   if (need_full_buffer) {
00265 #ifdef FULL_MAIN_BUFFER_SUPPORTED
00266     /* Allocate a full-image virtual array for each component */
00267     /* Note we pad the bottom to a multiple of the iMCU height */
00268     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
00269          ci++, compptr++) {
00270       main->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
00271         ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
00272          compptr->width_in_blocks * DCTSIZE,
00273          (JDIMENSION) jround_up((long) compptr->height_in_blocks,
00274                                 (long) compptr->v_samp_factor) * DCTSIZE,
00275          (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
00276     }
00277 #else
00278     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
00279 #endif
00280   } else {
00281 #ifdef FULL_MAIN_BUFFER_SUPPORTED
00282     main->whole_image[0] = NULL; /* flag for no virtual arrays */
00283 #endif
00284     /* Allocate a strip buffer for each component */
00285     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
00286          ci++, compptr++) {
00287       main->buffer[ci] = (*cinfo->mem->alloc_sarray)
00288         ((j_common_ptr) cinfo, JPOOL_IMAGE,
00289          compptr->width_in_blocks * DCTSIZE,
00290          (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
00291     }
00292   }
00293 }