media/libjpeg/jcmainct.c

   1 /*
   2  * jcmainct.c
   3  *
   4  * This file was part of the Independent JPEG Group's software:
   5  * Copyright (C) 1994-1996, Thomas G. Lane.
   6  * Lossless JPEG Modifications:
   7  * Copyright (C) 1999, Ken Murchison.
   8  * libjpeg-turbo Modifications:
   9  * Copyright (C) 2022, D. R. Commander.
  10  * For conditions of distribution and use, see the accompanying README.ijg
  11  * file.
  12  *
  13  * This file contains the main buffer controller for compression.
  14  * The main buffer lies between the pre-processor and the JPEG
  15  * compressor proper; it holds downsampled data in the JPEG colorspace.
  16  */
  17
  18 #define JPEG_INTERNALS
  19 #include "jinclude.h"
  20 #include "jpeglib.h"
  21 #include "jsamplecomp.h"
  22
  23
  24 #if BITS_IN_JSAMPLE != 16 || defined(C_LOSSLESS_SUPPORTED)
  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 } my_main_controller;
  42
  43 typedef my_main_controller *my_main_ptr;
  44
  45
  46 /* Forward declarations */
  47 METHODDEF(void) process_data_simple_main(j_compress_ptr cinfo,
  48                                          _JSAMPARRAY input_buf,
  49                                          JDIMENSION *in_row_ctr,
  50                                          JDIMENSION in_rows_avail);
  51
  52
  53 /*
  54  * Initialize for a processing pass.
  55  */
  56
  57 METHODDEF(void)
  58 start_pass_main(j_compress_ptr cinfo, J_BUF_MODE pass_mode)
  59 {
  60   my_main_ptr main_ptr = (my_main_ptr)cinfo->main;
  61
  62   /* Do nothing in raw-data mode. */
  63   if (cinfo->raw_data_in)
  64     return;
  65
  66   if (pass_mode != JBUF_PASS_THRU)
  67     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
  68
  69   main_ptr->cur_iMCU_row = 0;   /* initialize counters */
  70   main_ptr->rowgroup_ctr = 0;
  71   main_ptr->suspended = FALSE;
  72   main_ptr->pass_mode = pass_mode;      /* save mode for use by process_data */
  73   main_ptr->pub._process_data = process_data_simple_main;
  74 }
  75
  76
  77 /*
  78  * Process some data.
  79  * This routine handles the simple pass-through mode,
  80  * where we have only a strip buffer.
  81  */
  82
  83 METHODDEF(void)
  84 process_data_simple_main(j_compress_ptr cinfo, _JSAMPARRAY input_buf,
  85                          JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail)
  86 {
  87   my_main_ptr main_ptr = (my_main_ptr)cinfo->main;
  88   JDIMENSION data_unit = cinfo->master->lossless ? 1 : DCTSIZE;
  89
  90   while (main_ptr->cur_iMCU_row < cinfo->total_iMCU_rows) {
  91     /* Read input data if we haven't filled the main buffer yet */
  92     if (main_ptr->rowgroup_ctr < data_unit)
  93       (*cinfo->prep->_pre_process_data) (cinfo, input_buf, in_row_ctr,
  94                                          in_rows_avail, main_ptr->buffer,
  95                                          &main_ptr->rowgroup_ctr, data_unit);
  96
  97     /* If we don't have a full iMCU row buffered, return to application for
  98      * more data.  Note that preprocessor will always pad to fill the iMCU row
  99      * at the bottom of the image.
 100      */
 101     if (main_ptr->rowgroup_ctr != data_unit)
 102       return;
 103
 104     /* Send the completed row to the compressor */
 105     if (!(*cinfo->coef->_compress_data) (cinfo, main_ptr->buffer)) {
 106       /* If compressor did not consume the whole row, then we must need to
 107        * suspend processing and return to the application.  In this situation
 108        * we pretend we didn't yet consume the last input row; otherwise, if
 109        * it happened to be the last row of the image, the application would
 110        * think we were done.
 111        */
 112       if (!main_ptr->suspended) {
 113         (*in_row_ctr)--;
 114         main_ptr->suspended = TRUE;
 115       }
 116       return;
 117     }
 118     /* We did finish the row.  Undo our little suspension hack if a previous
 119      * call suspended; then mark the main buffer empty.
 120      */
 121     if (main_ptr->suspended) {
 122       (*in_row_ctr)++;
 123       main_ptr->suspended = FALSE;
 124     }
 125     main_ptr->rowgroup_ctr = 0;
 126     main_ptr->cur_iMCU_row++;
 127   }
 128 }
 129
 130
 131 /*
 132  * Initialize main buffer controller.
 133  */
 134
 135 GLOBAL(void)
 136 _jinit_c_main_controller(j_compress_ptr cinfo, boolean need_full_buffer)
 137 {
 138   my_main_ptr main_ptr;
 139   int ci;
 140   jpeg_component_info *compptr;
 141   int data_unit = cinfo->master->lossless ? 1 : DCTSIZE;
 142
 143   if (cinfo->data_precision != BITS_IN_JSAMPLE)
 144     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
 145
 146   main_ptr = (my_main_ptr)
 147     (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
 148                                 sizeof(my_main_controller));
 149   cinfo->main = (struct jpeg_c_main_controller *)main_ptr;
 150   main_ptr->pub.start_pass = start_pass_main;
 151
 152   /* We don't need to create a buffer in raw-data mode. */
 153   if (cinfo->raw_data_in)
 154     return;
 155
 156   /* Create the buffer.  It holds downsampled data, so each component
 157    * may be of a different size.
 158    */
 159   if (need_full_buffer) {
 160     ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
 161   } else {
 162     /* Allocate a strip buffer for each component */
 163     for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 164          ci++, compptr++) {
 165       main_ptr->buffer[ci] = (_JSAMPARRAY)(*cinfo->mem->alloc_sarray)
 166         ((j_common_ptr)cinfo, JPOOL_IMAGE,
 167          compptr->width_in_blocks * data_unit,
 168          (JDIMENSION)(compptr->v_samp_factor * data_unit));
 169     }
 170   }
 171 }
 172
 173 #endif /* BITS_IN_JSAMPLE != 16 || defined(C_LOSSLESS_SUPPORTED) */