#ifndef lint
static const char	RCSid[] = "$Id: colrops.c,v 2.6 2003/02/22 02:07:22 greg Exp $";
#endif
/*
 * Integer operations on COLR scanlines
 */

/* ====================================================================
 * The Radiance Software License, Version 1.0
 *
 * Copyright (c) 1990 - 2002 The Regents of the University of California,
 * through Lawrence Berkeley National Laboratory.   All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *         notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *           if any, must include the following acknowledgment:
 *             "This product includes Radiance software
 *                 (http://radsite.lbl.gov/)
 *                 developed by the Lawrence Berkeley National Laboratory
 *               (http://www.lbl.gov/)."
 *       Alternately, this acknowledgment may appear in the software itself,
 *       if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Radiance," "Lawrence Berkeley National Laboratory"
 *       and "The Regents of the University of California" must
 *       not be used to endorse or promote products derived from this
 *       software without prior written permission. For written
 *       permission, please contact radiance@radsite.lbl.gov.
 *
 * 5. Products derived from this software may not be called "Radiance",
 *       nor may "Radiance" appear in their name, without prior written
 *       permission of Lawrence Berkeley National Laboratory.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.   IN NO EVENT SHALL Lawrence Berkeley National Laboratory OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Lawrence Berkeley National Laboratory.   For more
 * information on Lawrence Berkeley National Laboratory, please see
 * <http://www.lbl.gov/>.
 */

#include <math.h>
#include "color.h"

#define NULL		0

extern char	*bmalloc();

#define MAXGSHIFT	31		/* maximum shift for gamma table */

static BYTE	*g_mant = NULL, *g_nexp = NULL;

static BYTE	(*g_bval)[256] = NULL;


int
setcolrcor(f, a2)		/* set brightness correction */
double	(*f)();
double	a2;
{
	double	mult;
	register int	i, j;
					/* allocate tables */
	if (g_bval == NULL && (g_bval =
			(BYTE (*)[256])bmalloc((MAXGSHIFT+1)*256)) == NULL)
		return(-1);
					/* compute colr -> gamb mapping */
	mult = 1.0/256.0;
	for (i = 0; i <= MAXGSHIFT; i++) {
		for (j = 0; j < 256; j++)
			g_bval[i][j] = 256.0 * (*f)((j+.5)*mult, a2);
		mult *= 0.5;
	}
	return(0);
}


int
setcolrinv(f, a2)		/* set inverse brightness correction */
double	(*f)();
double	a2;
{
	double	mult;
	register int	i, j;
					/* allocate tables */
	if (g_mant == NULL && (g_mant = (BYTE *)bmalloc(256)) == NULL)
		return(-1);
	if (g_nexp == NULL && (g_nexp = (BYTE *)bmalloc(256)) == NULL)
		return(-1);
					/* compute gamb -> colr mapping */
	i = 0;
	mult = 256.0;
	for (j = 256; j--; ) {
		while ((g_mant[j] = mult * (*f)((j+.5)/256.0, a2)) < 128) {
			i++;
			mult *= 2.0;
		}
		g_nexp[j] = i;
	}
	return(0);
}


int
setcolrgam(g)			/* set gamma conversion */
double	g;
{
	if (setcolrcor(pow, 1.0/g) < 0)
		return(-1);
	return(setcolrinv(pow, g));
}


int
colrs_gambs(scan, len)		/* convert scanline of colrs to gamma bytes */
register COLR	*scan;
int	len;
{
	register int	i, expo;

	if (g_bval == NULL)
		return(-1);
	while (len-- > 0) {
		expo = scan[0][EXP] - COLXS;
		if (expo < -MAXGSHIFT) {
			if (expo < -MAXGSHIFT-8) {
				scan[0][RED] =
				scan[0][GRN] =
				scan[0][BLU] = 0;
			} else {
				i = (-MAXGSHIFT-1) - expo;
				scan[0][RED] = 
				g_bval[MAXGSHIFT][((scan[0][RED]>>i)+1)>>1];
				scan[0][GRN] =
				g_bval[MAXGSHIFT][((scan[0][GRN]>>i)+1)>>1];
				scan[0][BLU] =
				g_bval[MAXGSHIFT][((scan[0][BLU]>>i)+1)>>1];
			}
		} else if (expo > 0) {
			if (expo > 8) {
				scan[0][RED] =
				scan[0][GRN] =
				scan[0][BLU] = 255;
			} else {
				i = (scan[0][RED]<<1 | 1) << (expo-1);
				scan[0][RED] = i > 255 ? 255 : g_bval[0][i];
				i = (scan[0][GRN]<<1 | 1) << (expo-1);
				scan[0][GRN] = i > 255 ? 255 : g_bval[0][i];
				i = (scan[0][BLU]<<1 | 1) << (expo-1);
				scan[0][BLU] = i > 255 ? 255 : g_bval[0][i];
			}
		} else {
			scan[0][RED] = g_bval[-expo][scan[0][RED]];
			scan[0][GRN] = g_bval[-expo][scan[0][GRN]];
			scan[0][BLU] = g_bval[-expo][scan[0][BLU]];
		}
		scan[0][EXP] = COLXS;
		scan++;
	}
	return(0);
}


int
gambs_colrs(scan, len)		/* convert gamma bytes to colr scanline */
register COLR	*scan;
int	len;
{
	register int	nexpo;

	if (g_mant == NULL | g_nexp == NULL)
		return(-1);
	while (len-- > 0) {
		nexpo = g_nexp[scan[0][RED]];
		if (g_nexp[scan[0][GRN]] < nexpo)
			nexpo = g_nexp[scan[0][GRN]];
		if (g_nexp[scan[0][BLU]] < nexpo)
			nexpo = g_nexp[scan[0][BLU]];
		if (nexpo < g_nexp[scan[0][RED]])
			scan[0][RED] = g_mant[scan[0][RED]]
					>> (g_nexp[scan[0][RED]]-nexpo);
		else
			scan[0][RED] = g_mant[scan[0][RED]];
		if (nexpo < g_nexp[scan[0][GRN]])
			scan[0][GRN] = g_mant[scan[0][GRN]]
					>> (g_nexp[scan[0][GRN]]-nexpo);
		else
			scan[0][GRN] = g_mant[scan[0][GRN]];
		if (nexpo < g_nexp[scan[0][BLU]])
			scan[0][BLU] = g_mant[scan[0][BLU]]
					>> (g_nexp[scan[0][BLU]]-nexpo);
		else
			scan[0][BLU] = g_mant[scan[0][BLU]];
		scan[0][EXP] = COLXS - nexpo;
		scan++;
	}
	return(0);
}


void
shiftcolrs(scan, len, adjust)	/* shift a scanline of colors by 2^adjust */
register COLR	*scan;
register int	len;
register int	adjust;
{
	int	minexp;

	if (adjust == 0)
		return;
	minexp = adjust < 0 ? -adjust : 0;
	while (len-- > 0) {
		if (scan[0][EXP] <= minexp)
			scan[0][RED] = scan[0][GRN] = scan[0][BLU] =
			scan[0][EXP] = 0;
		else
			scan[0][EXP] += adjust;
		scan++;
	}
}


void
normcolrs(scan, len, adjust)	/* normalize a scanline of colrs */
register COLR  *scan;
int  len;
int  adjust;
{
	register int  c;
	register int  shift;

	while (len-- > 0) {
		shift = scan[0][EXP] + adjust - COLXS;
		if (shift > 0) {
			if (shift > 8) {
				scan[0][RED] =
				scan[0][GRN] =
				scan[0][BLU] = 255;
			} else {
				shift--;
				c = (scan[0][RED]<<1 | 1) << shift;
				scan[0][RED] = c > 255 ? 255 : c;
				c = (scan[0][GRN]<<1 | 1) << shift;
				scan[0][GRN] = c > 255 ? 255 : c;
				c = (scan[0][BLU]<<1 | 1) << shift;
				scan[0][BLU] = c > 255 ? 255 : c;
			}
		} else if (shift < 0) {
			if (shift < -8) {
				scan[0][RED] =
				scan[0][GRN] =
				scan[0][BLU] = 0;
			} else {
				shift = -1-shift;
				scan[0][RED] = ((scan[0][RED]>>shift)+1)>>1;
				scan[0][GRN] = ((scan[0][GRN]>>shift)+1)>>1;
				scan[0][BLU] = ((scan[0][BLU]>>shift)+1)>>1;
			}
		}
		scan[0][EXP] = COLXS - adjust;
		scan++;
	}
}