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/* *****************************************************************************
 * bmp_xor.c -- Display a BMP, using XORs.
 * Copyright (C) 2011      Pierre "PierrotLL" Le Gall <legallpierre89@gmail.com>
 * Copyright (C) 2016-2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
 *
 * This file is part of libcarrot.
 * libcarrot is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 3.0 of the License,
 * or (at your option) any later version.
 *
 * libcarrot 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the libcarrot; if not, see <http://www.gnu.org/licenses/>.
 * ************************************************************************** */
#include <monochrome.h>

void ML_bmp_xor(const unsigned char *bmp, int x, int y, int width, int height)
{
	unsigned short line;
	char shift, *screen, *p=(char*)&line;
	int i, j, begin=0, end=height, real_width=(width-1>>3<<3)+8;
	if(!bmp || x<0 || x>128-width || y<1-height || y>63 || width<1 || height<1) return;
	if(y < 0) begin = -y;
	if(y+height > 64) end = 64-y;
	shift = 8-(x&7);
	screen = ML_vram_adress()+(y+begin<<4)+(x>>3);
	for(i=begin ; i<end ; i++)
	{
		for(j=0 ; j<width-1>>3 ; j++)
		{
			line = bmp[i*(real_width>>3)+j]<<shift;
			screen[j] ^= *p;
			if(shift!=8) screen[j+1] ^= *(p+1);
		}
		line = (bmp[i*(real_width>>3)+j] & -1<<(real_width-width))<<shift;
		screen[j] ^= *p;
		if(shift!=8 && x+real_width<129) screen[j+1] ^= *(p+1);
		screen += 16;
	}
}