#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <ggi/ggi.h>

typedef unsigned char byte;

static ggi_visual_t vis;
static ggi_color pal[256];

static void Init(void)
{
	ggiInit();
	vis = ggiOpen(NULL);
	if(!vis || ggiSetGraphMode(vis, 320,200, 320,200, GT_8BIT))
		exit(-1);
}
static void Done(void)
{
	ggiClose(vis);
	ggiExit(); 
}
static void SetPal(void)
{
	int a;
	
	for(a=0; a<15; a++)
		pal[a].r = pal[a].g = pal[a].b = (15-a) * 0xFFFF / 15;
	
	pal[254].r=0x0400; pal[254].g=0x2000;pal[254].b=0x7FFF;
	pal[255].r=0xFFFF; pal[255].g=0x3000;pal[255].b=0xFFFF;
	
	ggiSetPalette(vis, 0,256, pal);
}

static void Disp(const char *s)
{
	FILE *fp = fopen(s, "rb");
	
	int posi, swap=1, bits=16, nes=0;
	
	if(!fp)return;
	
	ggiSetGCForeground(vis, 255);
	
	for(posi=0; ; )
	{
		int sx, sy;
		
		fseek(fp, posi, SEEK_SET);
		
		for(sy=0; sy<25; sy++)
			for(sx=0; sx<32; sx++)
			{
				unsigned char Buf[64];
				unsigned x, y;
				
				int bx,by;
				
				switch(swap)
				{
					case 0:
						bx = sx;
						by = sy;
						break;
					case 1:
						bx = (sx&1) | ((sy&1)<<1) | (sx&~3);
						by = ((sx&2)>>1) | (sy&~1);
						break;
					case 2:
						bx = (sx&15) | ((sy&1)<<4);
						by = ((sx&16)>>4) | (sy&~1);
						break;
					case 3:
						bx = (sx&7) | ((sy&3)<<3) | (sx&~31);
						by = ((sx&24)>>3) | (sy&~3);
						break;
				}
				
				/*  1256 */
				/*  3478 */
				
				bx*=8;
				by*=8;
			
				if(fread(Buf, 1, bits, fp) != bits)
					for(y=0; y<8; y++)
						for(x=0; x<8; x++)
							ggiPutPixel(vis, bx+x, by+y, 254);
				else
					for(y=0; y<8; y++)
					{
						unsigned char b1, b2, b3, b4;
						
						if(bits==32)
						{
							b1 = Buf[y*2];
							b2 = Buf[y*2+1];
							b3 = Buf[y*2+16];
							b4 = Buf[y*2+17];
						}
						else
						{
							b1 = Buf[nes?y:y*bits/8];
							b2 = Buf[nes?y+8:y*bits/8+1];
						}
						switch(bits)
						{
							case 16:
								for(x=0; x<8; x++)
								{
									ggiPutPixel(vis, bx+x, by+y,
										(((b1 >> (7-x))&1) | (((b2 >> (7-x))&1)<<1)) * 15 / 3
									);
								}
								break;
							case 32:
								for(x=0; x<8; x++)
								{
									ggiPutPixel(vis, bx+x, by+y,
										((b1 >> (7-x))&1)
									  | (((b2 >> (7-x))&1)<<1)
									  | (((b3 >> (7-x))&1)<<2)
									  | (((b4 >> (7-x))&1)<<3)
									);
								}
								break;
							case 8:
								for(x=0; x<8; x++)
									ggiPutPixel(vis, bx+x, by+y, 15*((b1 >> (7-x))&1));
						}
					}
			}
		
		ggiPutc(vis,320-48+ 0,0, 'P');
		ggiPutc(vis,320-48+ 8,0, swap+'0');
		ggiPutc(vis,320-48+16,0, 'B');
		ggiPutc(vis,320-48+24,0, bits==8?'1':bits==16?'2':'4');
		ggiPutc(vis,320-48+32,0, 'N');
		ggiPutc(vis,320-48+40,0, nes+'0');
		
		ggiPuts(vis,256+6,16, "a,d =");
		ggiPuts(vis,256+6,24, "  shift");
		ggiPuts(vis,256+6,32, "w,s =");
		ggiPuts(vis,256+3,40, " up,down");
		ggiPuts(vis,256+6,48, "e,q =");
		ggiPuts(vis,256+6,56, " posi-+");
		ggiPuts(vis,256+3,64, "p=toggle");
		ggiPuts(vis,256+6,72, "   swap");
		ggiPuts(vis,256+3,80, "b=toggle");
		ggiPuts(vis,256+6,88, "   bits");
		ggiPuts(vis,256+3,96, "n=toggle");
		ggiPuts(vis,256+6,104," nes/gb");
		ggiPuts(vis,256+6,112,"esc=");
		ggiPuts(vis,256+6,120,"   quit");
		
		switch(ggiGetc(vis))
		{
			case 27: return;
			case 'a': if(posi>0)posi--; break;
			case 'd': posi++; break;
			case 's': posi+=2*32*bits; break;
			case 'w': posi-=2*32*bits; if(posi<0)posi=0; break;
			case 'e': posi+=4*bits; break;
			case 'q': posi-=4*bits; if(posi<0)posi=0; break;
			case 'p': swap=(swap+1)%4; break;
			case 'b': bits=bits==8?16:bits==16?32:8; break;
			case 'n': nes^=1; break;
		}
	}
}

int main(int argc, const char *const *argv)
{
	if(argc<2 || access(argv[argc-1], O_RDONLY))
	{
		printf(
			"Designed for Game Boy and NES files, but can be used on others as well\n"
			"Copyright (C) 1992,2000 Bisqwit (http://iki.fi/bisqwit/)\n"
			"Usage: xray <filename>\n");
		return 0;
	}
	Init();
	
	SetPal();
	
	Disp(argv[argc-1]);
	
	Done();

	return 0;
}