#include <u.h>
#include <libc.h>

typedef struct Ent Ent;
struct Ent
{
	ulong off;
	int dx;
	int dy;
	int yy;
};

int modes[] = {
	320, 200,
	320, 240,
	512, 384,
	640, 350,
	640, 400,
	640, 480,
	720, 400,
	768, 480,
	800, 600,
	1024, 768,
	1152, 864,
	1280, 800,
	1280, 1024,
	1400, 1050,
	1440, 900,
	1600, 1200,
	1680, 1050,
	1920, 1080,
	1920, 1200,
	2048, 1536,
	0,
};

int
entcmp(void *p1, void *p2)
{
	Ent *e1 = p1;
	Ent *e2 = p2;
	int n;

	if((n = e1->off - e2->off) == 0)
		n = e1->yy - e2->yy;
	return n;
}

void
main(int argc, char *argv[])
{
	uchar buf[4*64*1024], *p, *e;
	ulong oo, off, start;
	int fd, i, j;

	ARGBEGIN {
	} ARGEND;

	if(*argv == 0){
		fprint(2, "Usage: %s file [ off[+disp] val ... ]\n", argv0);
		exits("usage");
	}
	fd = open(*argv, ORDWR);
	if(fd < 0)
		sysfatal("open: %r");

	argv++;
	start = 0xC0000;
	if(*argv == 0){
		Ent ent[1024];
		int nent;

		nent = 0;
		off = start;
		if(seek(fd, off, 0) == -1)
			sysfatal("seek: %r");
		if(readn(fd, buf, sizeof(buf)) != sizeof(buf))
			sysfatal("read: %r");
		for(i=0; modes[i]; i += 2){
			for(p = buf, e = buf + sizeof(buf); p+32 < e; p++){
				if(p[0] != (modes[i] & 0xFF))
					continue;
				if(p[1] != (modes[i] >> 8))
					continue;
				for(j=2; j<30; j++){
					if(p[j] != (modes[i+1] & 0xFF))
						continue;
					if(p[j+1] != (modes[i+1] >> 8))
						continue;
					if(nent >= nelem(ent))
						break;
					ent[nent].off = off + (p - buf);
					ent[nent].dx = modes[i];
					ent[nent].dy = modes[i+1];
					ent[nent].yy = j;
					nent++;
				}
			}
		}

		qsort(ent, nent, sizeof(ent[0]), entcmp);
		for(j=2; j<30; j++){
			print("# y=x+%d\n", j);
			oo = 0;
			for(i=0; i<nent; i++){
				if(ent[i].yy != j)
					continue;
				print("%.5x (%lux) %dx%d\n", ent[i].off, ent[i].off - oo, 
					ent[i].dx, ent[i].dy);
				oo = ent[i].off;
			}
		}
	}
	while(argv[0] && argv[1]){
		char *s;
		s = nil;
		off = strtoul(argv[0], &s, 16);
		if(*s == '+')
			off += atoi(s+1);
		if(off < start)
			sysfatal("bad offset");
		if((i = atoi(argv[1])) <= 0)
			sysfatal("bad value");
		fprint(2, "writing %.5lux = %d\n", off, i);
		buf[0] = i & 0xFF;
		buf[1] = i >> 8;
		if(seek(fd, off, 0) == -1)
			sysfatal("seek: %r");
		if(write(fd, buf, 2) != 2)
			sysfatal("write: %r");
		argv += 2;
	}
	exits(0);
}