/* ************************************************************************** */
/*                                                                            */
/*  ML_bmp_xor.c                                                              */
/*  | Project : libmonochrome                                                 */
/*                                                                            */
/*  By: Pierre "PierrotLL" Le Gall <legallpierre89@gmail.com>                 */
/*  Last updated: 2011/11/22                                                  */
/*                                                                            */
/* ************************************************************************** */

#include <monochrome/internals.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;
	}
}