/*
 * Copyright (c) 1992 The Regents of the University of California.
 * All rights reserved.
 * 
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement is
 * hereby granted, provided that the above copyright notice and the following
 * two paragraphs appear in all copies of this software.
 * 
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */
/* This file contains C code to implement an ordered dither. */

#include "display.h"

#define DITH_SIZE 16


/* Structures used to implement hybrid ordered dither/floyd-steinberg
   dither algorithm.
*/

static unsigned char *l_darrays[DITH_SIZE];
static unsigned char *cr_darrays[DITH_SIZE];
static unsigned char *cb_darrays[DITH_SIZE];

/*
 *--------------------------------------------------------------
 *
 *  InitOrderedDither--
 *
 *	Structures intialized for ordered dithering. 
 *
 * Results:
 *	None.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */

void
InitOrderedDither()
{
  int i, j, k, err_range, threshval;
  unsigned char *lmark, *cmark;

  for (i=0; i<DITH_SIZE; i++) {
    lmark = l_darrays[i] = (unsigned char *) malloc(256);

    for (j=0; j<lum_values[0]; j++) {
      *lmark++ = 0;
    }

    for (j=0; j<(LUM_RANGE-1); j++) {
      err_range = lum_values[j+1] - lum_values[j];
      threshval = ((i * err_range) / DITH_SIZE)+lum_values[j];

      for (k=lum_values[j]; k<lum_values[j+1]; k++) {
	if (k > threshval) *lmark++ = ((j+1) * (CR_RANGE * CB_RANGE));
	else *lmark++ = (j * (CR_RANGE * CB_RANGE));
      }
    }

    for (j=lum_values[LUM_RANGE-1]; j<256; j++) {
      *lmark++ = (LUM_RANGE-1)*(CR_RANGE * CB_RANGE);
    }
  }

  for (i=0; i<DITH_SIZE; i++) {
    cmark = cr_darrays[i] = (unsigned char *) malloc(256);

    for (j=0; j<cr_values[0]; j++) {
      *cmark++ = 0;
    }

    for (j=0; j<(CR_RANGE-1); j++) {
      err_range = cr_values[j+1] - cr_values[j];
      threshval = ((i * err_range) / DITH_SIZE)+cr_values[j];

      for (k=cr_values[j]; k<cr_values[j+1]; k++) {
	if (k > threshval) *cmark++ = ((j+1) * CB_RANGE);
	else *cmark++ = (j * CB_RANGE);
      }
    }

    for (j=cr_values[CR_RANGE-1]; j<256; j++) {
      *cmark++ = (CR_RANGE-1)*(CB_RANGE);
    }
  }

  for (i=0; i<DITH_SIZE; i++) {
    cmark = cb_darrays[i] = (unsigned char *) malloc(256);

    for (j=0; j<cb_values[0]; j++) {
      *cmark++ = 0;
    }

    for (j=0; j<(CB_RANGE-1); j++) {
      err_range = cb_values[j+1] - cb_values[j];
      threshval = ((i * err_range) / DITH_SIZE)+cb_values[j];

      for (k=cb_values[j]; k<cb_values[j+1]; k++) {
	if (k > threshval) *cmark++ = j+1;
	else *cmark++ = j;
      }
    }

    for (j=cb_values[CB_RANGE-1]; j<256; j++) {
      *cmark++ = CB_RANGE-1;
    }
  }
}

/*
 *--------------------------------------------------------------
 *
 * OrderedDitherImage --
 *
 *	Dithers an image using an ordered dither.
 *	Assumptions made:
 *	  1) The color space is allocated y:cr:cb = 8:4:4
 *	  2) The spatial resolution of y:cr:cb is 4:1:1
 *      The channels are dithered based on the standard
 *      ordered dither pattern for a 4x4 area. 
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *--------------------------------------------------------------
 */
void
OrderedDitherImage (lum, cr, cb, out, h, w)
    unsigned char *lum;
    unsigned char *cr;
    unsigned char *cb;
    unsigned char *out;
    int w, h;
{
  unsigned char *l, *r, *b, *o1, *o2;
  unsigned char *l2;
  unsigned char L, R, B;
  int i, j;

  l = lum;
  l2 = lum+w;
  r = cr;
  b = cb;
  o1 = out;
  o2 = out+w;

  for (i=0; i<h; i+=4) {

    for (j=0; j<w; j+=8) {

      R = r[0]; B = b[0];

      L = l[0];
      o1[0] = pixel[(l_darrays[0][L] + cr_darrays[0][R] + cb_darrays[0][B])];
      L = l[1];
      o1[1] = pixel[(l_darrays[8][L] + cr_darrays[8][R] + cb_darrays[8][B])];
      L = l2[0];
      o2[0] = pixel[(l_darrays[12][L] + cr_darrays[12][R] + cb_darrays[12][B])];
      L = l2[1];
      o2[1] = pixel[(l_darrays[4][L] + cr_darrays[4][R] + cb_darrays[4][B])];

      R = r[1]; B = b[1];

      L = l[2];
      o1[2] = pixel[(l_darrays[2][L] + cr_darrays[2][R] + cb_darrays[2][B])];
      L = l[3];
      o1[3] = pixel[(l_darrays[10][L] + cr_darrays[10][R] + cb_darrays[10][B])];
      L = l2[2];
      o2[2] = pixel[(l_darrays[14][L] + cr_darrays[14][R] + cb_darrays[14][B])];
      L = l2[3];
      o2[3] = pixel[(l_darrays[6][L] + cr_darrays[6][R] + cb_darrays[6][B])];

      R = r[2]; B = b[2];

      L = l[4];
      o1[4] = pixel[(l_darrays[0][L] + cr_darrays[0][R] + cb_darrays[0][B])];
      L = l[5];
      o1[5] = pixel[(l_darrays[8][L] + cr_darrays[8][R] + cb_darrays[8][B])];
      L = l2[4];
      o2[4] = pixel[(l_darrays[12][L] + cr_darrays[12][R] + cb_darrays[12][B])];
      L = l2[5];
      o2[5] = pixel[(l_darrays[4][L] + cr_darrays[4][R] + cb_darrays[4][B])];

      R = r[3]; B = b[3];

      L = l[6];
      o1[6] = pixel[(l_darrays[2][L] + cr_darrays[2][R] + cb_darrays[2][B])];
      L = l[7];
      o1[7] = pixel[(l_darrays[10][L] + cr_darrays[10][R] + cb_darrays[10][B])];
      L = l2[6];
      o2[6] = pixel[(l_darrays[14][L] + cr_darrays[14][R] + cb_darrays[14][B])];
      L = l2[7];
      o2[7] = pixel[(l_darrays[6][L] + cr_darrays[6][R] + cb_darrays[6][B])];

      l += 8;
      l2 += 8;
      r += 4;
      b += 4;
      o1 += 8;
      o2 += 8;
    }

    l += w; l2 += w;
    o1 += w; o2 += w;

    for (j=0; j<w; j+=8) {

      R = r[0]; B = b[0];

      L = l[0];
      o1[0] = pixel[(l_darrays[3][L] + cr_darrays[3][R] + cb_darrays[3][B])];
      L = l[1];
      o1[1] = pixel[(l_darrays[11][L] + cr_darrays[11][R] + cb_darrays[11][B])];
      L = l2[0];
      o2[0] = pixel[(l_darrays[15][L] + cr_darrays[15][R] + cb_darrays[15][B])];
      L = l2[1];
      o2[1] = pixel[(l_darrays[7][L] + cr_darrays[7][R] + cb_darrays[7][B])];

      R = r[1]; B = b[1];

      L = l[2];
      o1[2] = pixel[(l_darrays[1][L] + cr_darrays[1][R] + cb_darrays[1][B])];
      L = l[3];
      o1[3] = pixel[(l_darrays[9][L] + cr_darrays[9][R] + cb_darrays[9][B])];
      L = l2[2];
      o2[2] = pixel[(l_darrays[13][L] + cr_darrays[13][R] + cb_darrays[13][B])];
      L = l2[3];
      o2[3] = pixel[(l_darrays[5][L] + cr_darrays[5][R] + cb_darrays[5][B])];

      R = r[2]; B = b[2];

      L = l[4];
      o1[4] = pixel[(l_darrays[3][L] + cr_darrays[3][R] + cb_darrays[3][B])];
      L = l[5];
      o1[5] = pixel[(l_darrays[11][L] + cr_darrays[11][R] + cb_darrays[11][B])];
      L = l2[4];
      o2[4] = pixel[(l_darrays[15][L] + cr_darrays[15][R] + cb_darrays[15][B])];
      L = l2[5];
      o2[5] = pixel[(l_darrays[7][L] + cr_darrays[7][R] + cb_darrays[7][B])];

      R = r[3]; B = b[3];

      L = l[6];
      o1[6] = pixel[(l_darrays[1][L] + cr_darrays[1][R] + cb_darrays[1][B])];
      L = l[7];
      o1[7] = pixel[(l_darrays[9][L] + cr_darrays[9][R] + cb_darrays[9][B])];
      L = l2[6];
      o2[6] = pixel[(l_darrays[13][L] + cr_darrays[13][R] + cb_darrays[13][B])];
      L = l2[7];
      o2[7] = pixel[(l_darrays[5][L] + cr_darrays[5][R] + cb_darrays[5][B])];

      l += 8;
      l2 += 8;
      r += 4;
      b += 4;
      o1 += 8;
      o2 += 8;
    }

    l += w; l2 += w;
    o1 += w; o2 += w;
  }
}