text: /*
   * jcmainct.c
   *
   * Copyright (C) 1994-1996, Thomas G. Lane.
   * This file is part of the Independent JPEG Group's software.
   * For conditions of distribution and use, see the accompanying README file.
   *
   * This file contains the main buffer controller for compression.
   * The main buffer lies between the pre-processor and the JPEG
   * compressor proper; it holds downsampled data in the JPEG colorspace.
   */
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "jpeglib.h"
  
  
  /* Note: currently, there is no operating mode in which a full-image buffer
   * is needed at this step.  If there were, that mode could not be used with
   * "raw data" input, since this module is bypassed in that case.  However,
   * we've left the code here for possible use in special applications.
   */
  #undef FULL_MAIN_BUFFER_SUPPORTED
  
  
  /* Private buffer controller object */
  
  typedef struct {
    struct jpeg_c_main_controller pub; /* public fields */
  
    JDIMENSION cur_iMCU_row;	/* number of current iMCU row */
    JDIMENSION rowgroup_ctr;	/* counts row groups received in iMCU row */
    jboolean suspended;		/* remember if we suspended output */
    J_BUF_MODE pass_mode;		/* current operating mode */
  
    /* If using just a strip buffer, this points to the entire set of buffers
     * (we allocate one for each component).  In the full-image case, this
     * points to the currently accessible strips of the virtual arrays.
     */
    JSAMPARRAY buffer[MAX_COMPONENTS];
  
  #ifdef FULL_MAIN_BUFFER_SUPPORTED
    /* If using full-image storage, this array holds pointers to virtual-array
     * control blocks for each component.  Unused if not full-image storage.
     */
    jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
  #endif
  } my_main_controller;
  
  typedef my_main_controller * my_main_ptr;
  
  
  /* Forward declarations */
  METHODDEF(void) process_data_simple_main
  	JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
  	     JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
  #ifdef FULL_MAIN_BUFFER_SUPPORTED
  METHODDEF(void) process_data_buffer_main
  	JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
  	     JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
  #endif
  
  
  /*
   * Initialize for a processing pass.
   */
  
  METHODDEF(void)
  start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
  {
    my_main_ptr main = (my_main_ptr) cinfo->main;
  
    /* Do nothing in raw-data mode. */
    if (cinfo->raw_data_in)
      return;
  
    main->cur_iMCU_row = 0;	/* initialize counters */
    main->rowgroup_ctr = 0;
    main->suspended = FALSE;
    main->pass_mode = pass_mode;	/* save mode for use by process_data */
  
    switch (pass_mode) {
    case JBUF_PASS_THRU:
  #ifdef FULL_MAIN_BUFFER_SUPPORTED
      if (main->whole_image[0] != NULL)
        ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
  #endif
      main->pub.process_data = process_data_simple_main;
      break;
  #ifdef FULL_MAIN_BUFFER_SUPPORTED
    case JBUF_SAVE_SOURCE:
    case JBUF_CRANK_DEST:
    case JBUF_SAVE_AND_PASS:
      if (main->whole_image[0] == NULL)
        ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
      main->pub.process_data = process_data_buffer_main;
      break;
  #endif
    default:
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
      break;
    }
  }
  
  
  /*
   * Process some data.
   * This routine handles the simple pass-through mode,
   * where we have only a strip buffer.
   */
  
  METHODDEF(void)
  process_data_simple_main (j_compress_ptr cinfo,
  			  JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
  			  JDIMENSION in_rows_avail)
  {
    my_main_ptr main = (my_main_ptr) cinfo->main;
  
    while (main->cur_iMCU_row < cinfo->total_iMCU_rows) {
      /* Read input data if we haven't filled the main buffer yet */
      if (main->rowgroup_ctr < DCTSIZE)
        (*cinfo->prep->pre_process_data) (cinfo,
  					input_buf, in_row_ctr, in_rows_avail,
  					main->buffer, &main->rowgroup_ctr,
  					(JDIMENSION) DCTSIZE);
  
      /* If we don't have a full iMCU row buffered, return to application for
       * more data.  Note that preprocessor will always pad to fill the iMCU row
       * at the bottom of the image.
       */
      if (main->rowgroup_ctr != DCTSIZE)
        return;
  
      /* Send the completed row to the compressor */
      if (! (*cinfo->coef->compress_data) (cinfo, main->buffer)) {
        /* If compressor did not consume the whole row, then we must need to
         * suspend processing and return to the application.  In this situation
         * we pretend we didn't yet consume the last input row; otherwise, if
         * it happened to be the last row of the image, the application would
         * think we were done.
         */
        if (! main->suspended) {
  	(*in_row_ctr)--;
  	main->suspended = TRUE;
        }
        return;
      }
      /* We did finish the row.  Undo our little suspension hack if a previous
       * call suspended; then mark the main buffer empty.
       */
      if (main->suspended) {
        (*in_row_ctr)++;
        main->suspended = FALSE;
      }
      main->rowgroup_ctr = 0;
      main->cur_iMCU_row++;
    }
  }
  
  
  #ifdef FULL_MAIN_BUFFER_SUPPORTED
  
  /*
   * Process some data.
   * This routine handles all of the modes that use a full-size buffer.
   */
  
  METHODDEF(void)
  process_data_buffer_main (j_compress_ptr cinfo,
  			  JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
  			  JDIMENSION in_rows_avail)
  {
    my_main_ptr main = (my_main_ptr) cinfo->main;
    int ci;
    jpeg_component_info *compptr;
    jboolean writing = (main->pass_mode != JBUF_CRANK_DEST);
  
    while (main->cur_iMCU_row < cinfo->total_iMCU_rows) {
      /* Realign the virtual buffers if at the start of an iMCU row. */
      if (main->rowgroup_ctr == 0) {
        for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
  	   ci++, compptr++) {
  	main->buffer[ci] = (*cinfo->mem->access_virt_sarray)
  	  ((j_common_ptr) cinfo, main->whole_image[ci],
  	   main->cur_iMCU_row * (compptr->v_samp_factor * DCTSIZE),
  	   (JDIMENSION) (compptr->v_samp_factor * DCTSIZE), writing);
        }
        /* In a read pass, pretend we just read some source data. */
        if (! writing) {
  	*in_row_ctr += cinfo->max_v_samp_factor * DCTSIZE;
  	main->rowgroup_ctr = DCTSIZE;
        }
      }
  
      /* If a write pass, read input data until the current iMCU row is full. */
      /* Note: preprocessor will pad if necessary to fill the last iMCU row. */
      if (writing) {
        (*cinfo->prep->pre_process_data) (cinfo,
  					input_buf, in_row_ctr, in_rows_avail,
  					main->buffer, &main->rowgroup_ctr,
  					(JDIMENSION) DCTSIZE);
        /* Return to application if we need more data to fill the iMCU row. */
        if (main->rowgroup_ctr < DCTSIZE)
  	return;
      }
  
      /* Emit data, unless this is a sink-only pass. */
      if (main->pass_mode != JBUF_SAVE_SOURCE) {
        if (! (*cinfo->coef->compress_data) (cinfo, main->buffer)) {
  	/* If compressor did not consume the whole row, then we must need to
  	 * suspend processing and return to the application.  In this situation
  	 * we pretend we didn't yet consume the last input row; otherwise, if
  	 * it happened to be the last row of the image, the application would
  	 * think we were done.
  	 */
  	if (! main->suspended) {
  	  (*in_row_ctr)--;
  	  main->suspended = TRUE;
  	}
  	return;
        }
        /* We did finish the row.  Undo our little suspension hack if a previous
         * call suspended; then mark the main buffer empty.
         */
        if (main->suspended) {
  	(*in_row_ctr)++;
  	main->suspended = FALSE;
        }
      }
  
      /* If get here, we are done with this iMCU row.  Mark buffer empty. */
      main->rowgroup_ctr = 0;
      main->cur_iMCU_row++;
    }
  }
  
  #endif /* FULL_MAIN_BUFFER_SUPPORTED */
  
  
  /*
   * Initialize main buffer controller.
   */
  
  GLOBAL(void)
  jinit_c_main_controller (j_compress_ptr cinfo, jboolean need_full_buffer)
  {
    my_main_ptr main;
    int ci;
    jpeg_component_info *compptr;
  
    main = (my_main_ptr)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
  				SIZEOF(my_main_controller));
    cinfo->main = (struct jpeg_c_main_controller *) main;
    main->pub.start_pass = start_pass_main;
  
    /* We don't need to create a buffer in raw-data mode. */
    if (cinfo->raw_data_in)
      return;
  
    /* Create the buffer.  It holds downsampled data, so each component
     * may be of a different size.
     */
    if (need_full_buffer) {
  #ifdef FULL_MAIN_BUFFER_SUPPORTED
      /* Allocate a full-image virtual array for each component */
      /* Note we pad the bottom to a multiple of the iMCU height */
      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
  	 ci++, compptr++) {
        main->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
  	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
  	 compptr->width_in_blocks * DCTSIZE,
  	 (JDIMENSION) jround_up((long) compptr->height_in_blocks,
  				(long) compptr->v_samp_factor) * DCTSIZE,
  	 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
      }
  #else
      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
  #endif
    } else {
  #ifdef FULL_MAIN_BUFFER_SUPPORTED
      main->whole_image[0] = NULL; /* flag for no virtual arrays */
  #endif
      /* Allocate a strip buffer for each component */
      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
  	 ci++, compptr++) {
        main->buffer[ci] = (*cinfo->mem->alloc_sarray)
  	((j_common_ptr) cinfo, JPOOL_IMAGE,
  	 compptr->width_in_blocks * DCTSIZE,
  	 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
      }
    }
  }
  