/*

 * jdmainct.h

 *

 * This file was part of the Independent JPEG Group's software:

 * Copyright (C) 1994-1996, Thomas G. Lane.

 * For conditions of distribution and use, see the accompanying README.ijg

 * file.

 */

#define JPEG_INTERNALS

#include "jpeglib.h"

#include "jpegcomp.h"

/* Private buffer controller object */

typedef struct {

  struct jpeg_d_main_controller pub; /* public fields */

  /* Pointer to allocated workspace (M or M+2 row groups). */

  JSAMPARRAY buffer[MAX_COMPONENTS];

  boolean buffer_full;          /* Have we gotten an iMCU row from decoder? */

  JDIMENSION rowgroup_ctr;      /* counts row groups output to postprocessor */

  /* Remaining fields are only used in the context case. */

  /* These are the master pointers to the funny-order pointer lists. */

  JSAMPIMAGE xbuffer[2];        /* pointers to weird pointer lists */

  int whichptr;                 /* indicates which pointer set is now in use */

  int context_state;            /* process_data state machine status */

  JDIMENSION rowgroups_avail;   /* row groups available to postprocessor */

  JDIMENSION iMCU_row_ctr;      /* counts iMCU rows to detect image top/bot */

} my_main_controller;

typedef my_main_controller *my_main_ptr;

/* context_state values: */

#define CTX_PREPARE_FOR_IMCU    0       /* need to prepare for MCU row */

#define CTX_PROCESS_IMCU        1       /* feeding iMCU to postprocessor */

#define CTX_POSTPONED_ROW       2       /* feeding postponed row group */

LOCAL(void)

set_wraparound_pointers(j_decompress_ptr cinfo)

/* Set up the "wraparound" pointers at top and bottom of the pointer lists.

 * This changes the pointer list state from top-of-image to the normal state.

 */

{

  my_main_ptr main_ptr = (my_main_ptr)cinfo->main;

  int ci, i, rgroup;

  int M = cinfo->_min_DCT_scaled_size;

  jpeg_component_info *compptr;

  JSAMPARRAY xbuf0, xbuf1;

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

       ci++, compptr++) {

    rgroup = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /

      cinfo->_min_DCT_scaled_size; /* height of a row group of component */

    xbuf0 = main_ptr->xbuffer[0][ci];

    xbuf1 = main_ptr->xbuffer[1][ci];

    for (i = 0; i < rgroup; i++) {

      xbuf0[i - rgroup] = xbuf0[rgroup * (M + 1) + i];

      xbuf1[i - rgroup] = xbuf1[rgroup * (M + 1) + i];

      xbuf0[rgroup * (M + 2) + i] = xbuf0[i];

      xbuf1[rgroup * (M + 2) + i] = xbuf1[i];

    }

  }

}