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

#include <monochrome/internals.h>

void ML_bmp_xor_cl(const unsigned char *bmp, int x, int y, int width, int height)
{
	unsigned short line;
	char shift, *screen, *p;
	int i, j, real_width, begin_x, end_x, begin_y, end_y;
	char bool1=1, bool2=1, bool3;
	if(!bmp || x<1-width || x>127 || y<1-height || y>63 || height<1 || width<1) return;
	p = (char*)&line;
	real_width = (width-1>>3<<3)+8;
	if(y < 0) begin_y = -y;
	else begin_y = 0;
	if(y+height > 64) end_y = 64-y;
	else end_y = height;
	shift = 8-(x&7);
	if(x<0)
	{
		begin_x = -x>>3;
		if(shift != 8) bool1 = 0;
	} else begin_x = 0;
	if(x+real_width > 128) end_x = 15-(x>>3), bool2 = 0;
	else end_x = real_width-1>>3;
	bool3 = (end_x == real_width-1>>3);
	screen = ML_vram_adress()+(y+begin_y<<4)+(x>>3);

	for(i=begin_y ; i<end_y ; i++)
	{
		if(begin_x < end_x)
		{
			line = bmp[i*(real_width>>3)+begin_x] << shift;
			if(bool1) screen[begin_x] ^= *p;
			if(shift!=8) screen[begin_x+1] ^= *(p+1);
			for(j=begin_x+1 ; j<end_x ; 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)+end_x];
		if(bool3) line &= -1<<real_width-width;
		line <<= shift;
		if(begin_x < end_x || bool1) screen[end_x] ^= *p;
		if(bool2) screen[end_x+1] ^= *(p+1);
		screen += 16;
	}
}