    /*
     * 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 */
      int 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;
      int 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, int 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));
        }
      }
    }