/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */

#ifndef GRAPHICS_SCALER_INTERN_H
#define GRAPHICS_SCALER_INTERN_H

#include "common/scummsys.h"
#include "graphics/colormasks.h"


/**
 * Interpolate two 16 bit pixel *pairs* at once with equal weights 1.
 * In particular, p1 and p2 can contain two pixels each in the upper
 * and lower halves.
 */
template<typename ColorMask>
static inline uint32 interpolate32_1_1(uint32 p1, uint32 p2) {
	return (((p1 & ColorMask::kHighBitsMask) >> 1) +
	        ((p2 & ColorMask::kHighBitsMask) >> 1) +
	         (p1 & p2 & ColorMask::kLowBitsMask));
}

/**
 * Interpolate two 16 bit pixel *pairs* at once with weights 3 resp. 1.
 * In particular, p1 and p2 can contain two pixels/each in the upper
 * and lower halves.
 */
template<typename ColorMask>
static inline uint32 interpolate32_3_1(uint32 p1, uint32 p2) {
	register uint32 x = ((p1 & ColorMask::qhighBits) >> 2) * 3 + ((p2 & ColorMask::qhighBits) >> 2);
	register uint32 y = ((p1 & ColorMask::qlowBits) * 3 + (p2 & ColorMask::qlowBits)) >> 2;

	y &= ColorMask::qlowBits;
	return x + y;
}

/**
 * Interpolate two 16 bit pixels with weights 1 and 1, i.e., (p1+p2)/2.
 * See <http://www.slack.net/~ant/info/rgb_mixing.html> for details on how this works.
 */
template<typename ColorMask>
static inline unsigned interpolate16_1_1(unsigned p1, unsigned p2) {
	const unsigned lowbits = (p1 ^ p2) & ColorMask::kLowBits;
	return ((p1 + p2) - lowbits) >> 1;
}

/**
 * Interpolate two 16 bit pixels with weights 3 and 1, i.e., (3*p1+p2)/4.
 */
template<typename ColorMask>
static inline unsigned interpolate16_3_1(unsigned p1, unsigned p2) {
	const unsigned lowbits = (((p1 & ColorMask::kLowBits) << 1) + (p1 & ColorMask::kLow2Bits)
		                   + (p2 & ColorMask::kLow2Bits)) & ColorMask::kLow2Bits;
	return ((p1*3 + p2) - lowbits) >> 2;
}

/**
 * Interpolate two 16 bit pixels with weights 5 and 3 and 1, i.e., (5*p1+3*p2)/8.
 */
template<typename ColorMask>
static inline unsigned interpolate16_5_3(unsigned p1, unsigned p2) {
	const unsigned lowbits = (((p1 & ColorMask::kLowBits) << 2) + (p1 & ColorMask::kLow3Bits)
		                   + ((p2 & ColorMask::kLow2Bits) << 1) + (p2 & ColorMask::kLow3Bits)) & ColorMask::kLow3Bits;
	return ((p1*5 + p2*3) - lowbits) >> 3;
}

/**
 * Interpolate two 16 bit pixels with weights 7 and 1, i.e., (7*p1+p2)/8.
 */
template<typename ColorMask>
static inline unsigned interpolate16_7_1(unsigned p1, unsigned p2) {
	const unsigned lowbits = (((p1 & ColorMask::kLowBits) << 2) + ((p1 & ColorMask::kLow2Bits) << 1) + (p1 & ColorMask::kLow3Bits)
		                   +  (p2 & ColorMask::kLow3Bits)) & ColorMask::kLow3Bits;
	return ((p1*7+p2) - lowbits) >> 3;
}

/**
 * Interpolate three 16 bit pixels with weights 2, 1, and 1, i.e., (2*p1+p2+p3)/4.
 */
template<typename ColorMask>
static inline unsigned interpolate16_2_1_1(unsigned p1, unsigned p2, unsigned p3) {
	p1<<=1;
	const unsigned lowbits = ((p1 & (ColorMask::kLowBits << 1))
		                   +  (p2 & ColorMask::kLow2Bits)
		                   +  (p3 & ColorMask::kLow2Bits)) & ColorMask::kLow2Bits;
	return ((p1+p2+p3) - lowbits) >> 2;
}

/**
 * Interpolate three 16 bit pixels with weights 5, 2, and 1, i.e., (5*p1+2*p2+p3)/8.
 */
template<typename ColorMask>
static inline unsigned interpolate16_5_2_1(unsigned p1, unsigned p2, unsigned p3) {
	p2<<=1;
	const unsigned lowbits = (((p1 & ColorMask::kLowBits) << 2) + (p1 & ColorMask::kLow3Bits)
		                   +  (p2 & (ColorMask::kLow2Bits << 1))
		                   +  (p3 & ColorMask::kLow3Bits)) & ColorMask::kLow3Bits;
	return ((p1*5 + p2 + p3) - lowbits) >> 3;
}

/**
 * Interpolate three 16 bit pixels with weights 6, 1, and 1, i.e., (6*p1+p2+p3)/8.
 */
template<typename ColorMask>
static inline unsigned interpolate16_6_1_1(unsigned p1, unsigned p2, unsigned p3) {
	const unsigned lowbits = (((((p1 & ColorMask::kLowBits) << 1) + (p1 & ColorMask::kLow2Bits)) << 1)
		                   + (p2 & ColorMask::kLow3Bits)
		                   + (p3 & ColorMask::kLow3Bits)) & ColorMask::kLow3Bits;
	return ((p1*6 + p2 + p3) - lowbits) >> 3;
}

/**
 * Interpolate three 16 bit pixels with weights 2, 3, and 3, i.e., (2*p1+3*(p2+p3))/8.
 */
template<typename ColorMask>
static inline unsigned interpolate16_2_3_3(unsigned p1, unsigned p2, unsigned p3) {
	p1 <<= 1;
	const unsigned rb = (p1 & (ColorMask::kRedBlueMask<<1))
		              + ((p2 & ColorMask::kRedBlueMask) + (p3 & ColorMask::kRedBlueMask))*3;
	const unsigned  g = (p1 & (ColorMask::kGreenMask<<1))
		              + ((p2 & ColorMask::kGreenMask) + (p3 & ColorMask::kGreenMask))*3;
	return ((rb & (ColorMask::kRedBlueMask<<3)) | (g & (ColorMask::kGreenMask<<3))) >> 3;
}

/**
 * Interpolate three 16 bit pixels with weights 2, 7, and 7, i.e., (2*p1+7*(p2+p3))/16.
 */
template<typename ColorMask>
static inline unsigned interpolate16_2_7_7(unsigned p1, unsigned p2, unsigned p3) {
	p1 <<= 1;
	const unsigned rb = (p1 & (ColorMask::kRedBlueMask<<1))
		              + ((p2 & ColorMask::kRedBlueMask) + (p3 & ColorMask::kRedBlueMask))*7;
	const unsigned  g = (p1 & (ColorMask::kGreenMask<<1))
		              + ((p2 & ColorMask::kGreenMask) + (p3 & ColorMask::kGreenMask))*7;
	return ((rb & (ColorMask::kRedBlueMask<<4)) | (g & (ColorMask::kGreenMask<<4))) >> 4;
}

/**
 * Interpolate three 16 bit pixels with weights 14, 1, and 1, i.e., (14*p1+p2+p3)/16.
 */
template<typename ColorMask>
static inline unsigned interpolate16_14_1_1(unsigned p1, unsigned p2, unsigned p3) {
	const unsigned rb = (p1&ColorMask::kRedBlueMask)*14
	                  + (p2&ColorMask::kRedBlueMask)
	                  + (p3&ColorMask::kRedBlueMask);
	const unsigned  g = (p1&ColorMask::kGreenMask)*14
	                  + (p2&ColorMask::kGreenMask) + (p3&ColorMask::kGreenMask);
	return ((rb&(ColorMask::kRedBlueMask<<4)) | (g&(ColorMask::kGreenMask<<4))) >> 4;
}

/**
 * Interpolate four 16 bit pixels with weights 1, 1, 1, and 1, i.e., (p1+p2+p3+p4)/4.
 */
template<typename ColorMask>
static inline unsigned interpolate16_1_1_1_1(unsigned p1, unsigned p2, unsigned p3, unsigned p4) {
	const unsigned lowbits = ((p1 & ColorMask::kLow2Bits)
		                   +  (p2 & ColorMask::kLow2Bits)
		                   +  (p3 & ColorMask::kLow2Bits)
		                   +  (p4 & ColorMask::kLow2Bits)) & ColorMask::kLow2Bits;
	return ((p1+p2+p3+p4) - lowbits) >> 2;
}

/**
 * Compare two YUV values (encoded 8-8-8) and check if they differ by more than
 * a certain hard coded threshold. Used by the hq scaler family.
 */
static inline bool diffYUV(int yuv1, int yuv2) {
	static const int Ymask = 0x00FF0000;
	static const int Umask = 0x0000FF00;
	static const int Vmask = 0x000000FF;
	static const int trY   = 0x00300000;
	static const int trU   = 0x00000700;
	static const int trV   = 0x00000006;

	int diff;
	int mask;

	diff = ((yuv1 & Umask) - (yuv2 & Umask));
	mask = diff >> 31; // -1 if value < 0, 0 otherwise
	diff = (diff ^ mask) - mask; //-1: ~value + 1; 0: value
	if (diff > trU) return true;

	diff = ((yuv1 & Vmask) - (yuv2 & Vmask));
	mask = diff >> 31; // -1 if value < 0, 0 otherwise
	diff = (diff ^ mask) - mask; //-1: ~value + 1; 0: value
	if (diff > trV) return true;

	diff = ((yuv1 & Ymask) - (yuv2 & Ymask));
	mask = diff >> 31; // -1 if value < 0, 0 otherwise
	diff = (diff ^ mask) - mask; //-1: ~value + 1; 0: value
	if (diff > trY) return true;

	return false;
/*
	return
	  ( ( ABS((yuv1 & Ymask) - (yuv2 & Ymask)) > trY ) ||
	    ( ABS((yuv1 & Umask) - (yuv2 & Umask)) > trU ) ||
	    ( ABS((yuv1 & Vmask) - (yuv2 & Vmask)) > trV ) );
*/
}

#endif
