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      1 /*
      2  * jcmainct.c
      3  *
      4  * Copyright (C) 1994-1996, Thomas G. Lane.
      5  * This file is part of the Independent JPEG Group's software.
      6  * For conditions of distribution and use, see the accompanying README file.
      7  *
      8  * This file contains the main buffer controller for compression.
      9  * The main buffer lies between the pre-processor and the JPEG
     10  * compressor proper; it holds downsampled data in the JPEG colorspace.
     11  */
     12 
     13 #define JPEG_INTERNALS
     14 #include "jinclude.h"
     15 #include "jpeglib.h"
     16 
     17 
     18 /* Note: currently, there is no operating mode in which a full-image buffer
     19  * is needed at this step.  If there were, that mode could not be used with
     20  * "raw data" input, since this module is bypassed in that case.  However,
     21  * we've left the code here for possible use in special applications.
     22  */
     23 #undef FULL_MAIN_BUFFER_SUPPORTED
     24 
     25 
     26 /* Private buffer controller object */
     27 
     28 typedef struct {
     29   struct jpeg_c_main_controller pub; /* public fields */
     30 
     31   JDIMENSION cur_iMCU_row;	/* number of current iMCU row */
     32   JDIMENSION rowgroup_ctr;	/* counts row groups received in iMCU row */
     33   boolean suspended;		/* remember if we suspended output */
     34   J_BUF_MODE pass_mode;		/* current operating mode */
     35 
     36   /* If using just a strip buffer, this points to the entire set of buffers
     37    * (we allocate one for each component).  In the full-image case, this
     38    * points to the currently accessible strips of the virtual arrays.
     39    */
     40   JSAMPARRAY buffer[MAX_COMPONENTS];
     41 
     42 #ifdef FULL_MAIN_BUFFER_SUPPORTED
     43   /* If using full-image storage, this array holds pointers to virtual-array
     44    * control blocks for each component.  Unused if not full-image storage.
     45    */
     46   jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
     47 #endif
     48 } my_main_controller;
     49 
     50 typedef my_main_controller * my_main_ptr;
     51 
     52 
     53 /* Forward declarations */
     54 METHODDEF(void) process_data_simple_main
     55 	JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
     56 	     JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
     57 #ifdef FULL_MAIN_BUFFER_SUPPORTED
     58 METHODDEF(void) process_data_buffer_main
     59 	JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
     60 	     JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
     61 #endif
     62 
     63 
     64 /*
     65  * Initialize for a processing pass.
     66  */
     67 
     68 METHODDEF(void)
     69 start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
     70 {
     71   my_main_ptr main = (my_main_ptr) cinfo->main;
     72 
     73   /* Do nothing in raw-data mode. */
     74   if (cinfo->raw_data_in)
     75     return;
     76 
     77   main->cur_iMCU_row = 0;	/* initialize counters */
     78   main->rowgroup_ctr = 0;
     79   main->suspended = FALSE;
     80   main->pass_mode = pass_mode;	/* save mode for use by process_data */
     81 
     82   switch (pass_mode) {
     83   case JBUF_PASS_THRU:
     84 #ifdef FULL_MAIN_BUFFER_SUPPORTED
     85     if (main->whole_image[0] != NULL)
     86       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
     87 #endif
     88     main->pub.process_data = process_data_simple_main;
     89     break;
     90 #ifdef FULL_MAIN_BUFFER_SUPPORTED
     91   case JBUF_SAVE_SOURCE:
     92   case JBUF_CRANK_DEST:
     93   case JBUF_SAVE_AND_PASS:
     94     if (main->whole_image[0] == NULL)
     95       ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
     96     main->pub.process_data = process_data_buffer_main;
     97     break;
     98 #endif
     99   default:
    100     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
    101     break;
    102   }
    103 }
    104 
    105 
    106 /*
    107  * Process some data.
    108  * This routine handles the simple pass-through mode,
    109  * where we have only a strip buffer.
    110  */
    111 
    112 METHODDEF(void)
    113 process_data_simple_main (j_compress_ptr cinfo,
    114 			  JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
    115 			  JDIMENSION in_rows_avail)
    116 {
    117   my_main_ptr main = (my_main_ptr) cinfo->main;
    118 
    119   while (main->cur_iMCU_row < cinfo->total_iMCU_rows) {
    120     /* Read input data if we haven't filled the main buffer yet */
    121     if (main->rowgroup_ctr < DCTSIZE)
    122       (*cinfo->prep->pre_process_data) (cinfo,
    123 					input_buf, in_row_ctr, in_rows_avail,
    124 					main->buffer, &main->rowgroup_ctr,
    125 					(JDIMENSION) DCTSIZE);
    126 
    127     /* If we don't have a full iMCU row buffered, return to application for
    128      * more data.  Note that preprocessor will always pad to fill the iMCU row
    129      * at the bottom of the image.
    130      */
    131     if (main->rowgroup_ctr != DCTSIZE)
    132       return;
    133 
    134     /* Send the completed row to the compressor */
    135     if (! (*cinfo->coef->compress_data) (cinfo, main->buffer)) {
    136       /* If compressor did not consume the whole row, then we must need to
    137        * suspend processing and return to the application.  In this situation
    138        * we pretend we didn't yet consume the last input row; otherwise, if
    139        * it happened to be the last row of the image, the application would
    140        * think we were done.
    141        */
    142       if (! main->suspended) {
    143 	(*in_row_ctr)--;
    144 	main->suspended = TRUE;
    145       }
    146       return;
    147     }
    148     /* We did finish the row.  Undo our little suspension hack if a previous
    149      * call suspended; then mark the main buffer empty.
    150      */
    151     if (main->suspended) {
    152       (*in_row_ctr)++;
    153       main->suspended = FALSE;
    154     }
    155     main->rowgroup_ctr = 0;
    156     main->cur_iMCU_row++;
    157   }
    158 }
    159 
    160 
    161 #ifdef FULL_MAIN_BUFFER_SUPPORTED
    162 
    163 /*
    164  * Process some data.
    165  * This routine handles all of the modes that use a full-size buffer.
    166  */
    167 
    168 METHODDEF(void)
    169 process_data_buffer_main (j_compress_ptr cinfo,
    170 			  JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
    171 			  JDIMENSION in_rows_avail)
    172 {
    173   my_main_ptr main = (my_main_ptr) cinfo->main;
    174   int ci;
    175   jpeg_component_info *compptr;
    176   boolean writing = (main->pass_mode != JBUF_CRANK_DEST);
    177 
    178   while (main->cur_iMCU_row < cinfo->total_iMCU_rows) {
    179     /* Realign the virtual buffers if at the start of an iMCU row. */
    180     if (main->rowgroup_ctr == 0) {
    181       for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
    182 	   ci++, compptr++) {
    183 	main->buffer[ci] = (*cinfo->mem->access_virt_sarray)
    184 	  ((j_common_ptr) cinfo, main->whole_image[ci],
    185 	   main->cur_iMCU_row * (compptr->v_samp_factor * DCTSIZE),
    186 	   (JDIMENSION) (compptr->v_samp_factor * DCTSIZE), writing);
    187       }
    188       /* In a read pass, pretend we just read some source data. */
    189       if (! writing) {
    190 	*in_row_ctr += cinfo->max_v_samp_factor * DCTSIZE;
    191 	main->rowgroup_ctr = DCTSIZE;
    192       }
    193     }
    194 
    195     /* If a write pass, read input data until the current iMCU row is full. */
    196     /* Note: preprocessor will pad if necessary to fill the last iMCU row. */
    197     if (writing) {
    198       (*cinfo->prep->pre_process_data) (cinfo,
    199 					input_buf, in_row_ctr, in_rows_avail,
    200 					main->buffer, &main->rowgroup_ctr,
    201 					(JDIMENSION) DCTSIZE);
    202       /* Return to application if we need more data to fill the iMCU row. */
    203       if (main->rowgroup_ctr < DCTSIZE)
    204 	return;
    205     }
    206 
    207     /* Emit data, unless this is a sink-only pass. */
    208     if (main->pass_mode != JBUF_SAVE_SOURCE) {
    209       if (! (*cinfo->coef->compress_data) (cinfo, main->buffer)) {
    210 	/* If compressor did not consume the whole row, then we must need to
    211 	 * suspend processing and return to the application.  In this situation
    212 	 * we pretend we didn't yet consume the last input row; otherwise, if
    213 	 * it happened to be the last row of the image, the application would
    214 	 * think we were done.
    215 	 */
    216 	if (! main->suspended) {
    217 	  (*in_row_ctr)--;
    218 	  main->suspended = TRUE;
    219 	}
    220 	return;
    221       }
    222       /* We did finish the row.  Undo our little suspension hack if a previous
    223        * call suspended; then mark the main buffer empty.
    224        */
    225       if (main->suspended) {
    226 	(*in_row_ctr)++;
    227 	main->suspended = FALSE;
    228       }
    229     }
    230 
    231     /* If get here, we are done with this iMCU row.  Mark buffer empty. */
    232     main->rowgroup_ctr = 0;
    233     main->cur_iMCU_row++;
    234   }
    235 }
    236 
    237 #endif /* FULL_MAIN_BUFFER_SUPPORTED */
    238 
    239 
    240 /*
    241  * Initialize main buffer controller.
    242  */
    243 
    244 GLOBAL(void)
    245 jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
    246 {
    247   my_main_ptr main;
    248   int ci;
    249   jpeg_component_info *compptr;
    250 
    251   main = (my_main_ptr)
    252     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    253 				SIZEOF(my_main_controller));
    254   cinfo->main = (struct jpeg_c_main_controller *) main;
    255   main->pub.start_pass = start_pass_main;
    256 
    257   /* We don't need to create a buffer in raw-data mode. */
    258   if (cinfo->raw_data_in)
    259     return;
    260 
    261   /* Create the buffer.  It holds downsampled data, so each component
    262    * may be of a different size.
    263    */
    264   if (need_full_buffer) {
    265 #ifdef FULL_MAIN_BUFFER_SUPPORTED
    266     /* Allocate a full-image virtual array for each component */
    267     /* Note we pad the bottom to a multiple of the iMCU height */
    268     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
    269 	 ci++, compptr++) {
    270       main->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
    271 	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
    272 	 compptr->width_in_blocks * DCTSIZE,
    273 	 (JDIMENSION) jround_up((long) compptr->height_in_blocks,
    274 				(long) compptr->v_samp_factor) * DCTSIZE,
    275 	 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
    276     }
    277 #else
    278     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
    279 #endif
    280   } else {
    281 #ifdef FULL_MAIN_BUFFER_SUPPORTED
    282     main->whole_image[0] = NULL; /* flag for no virtual arrays */
    283 #endif
    284     /* Allocate a strip buffer for each component */
    285     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
    286 	 ci++, compptr++) {
    287       main->buffer[ci] = (*cinfo->mem->alloc_sarray)
    288 	((j_common_ptr) cinfo, JPOOL_IMAGE,
    289 	 compptr->width_in_blocks * DCTSIZE,
    290 	 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
    291     }
    292   }
    293 }
    294