/*
 * TeKtronix 603 storage monitor driver.
 * written at St. Joseph's Hospital, by Geoff Collyer, 12 Jan 1979.
 */ 

# include "../param.h"
# include "../user.h"

# define TKPRI 8	/* same as VTPRI */
# define TKADDR 0166760
struct tkreg {
	int x;
	int y;
	int unused;
	int csr;
};

/* hardware bits in csr */ 
# define READY 0200
# define IENABLE 0100
# define YINTENS 020
# define XINTENS 010
# define VARIAB (YINTENS | XINTENS)	/* variable brightness */
# define ERASE 02
# define INTENSIFY 01

/* misc. */ 
# define COORDMASK 03777	/* 11 bits wide */
# define READ 0
# define OPEN 1
# define CLOSED 0
# define NO_MORE (-1)

# define tkbuild(low, high) (((high)<<8) | ((low)&0377))

int tkstate CLOSED;
int tki;
char tkc[4];

tkopen(dev, flag) {
	if(flag == READ || tkstate == OPEN) {
		u.u_error = ENXIO;
		return;
	}
	tkstate = OPEN;
	tki = 0;
	TKADDR->csr = ERASE|IENABLE;
}

tkclose(dev, flag) {
	tkwait();
	TKADDR->csr |= VARIAB;
	tkstate = CLOSED;
}

tkwrite(dev) {
	register int xc, yc;
	register int c;

	for(; ; ) {
		for(; tki < 4; tki++) {
			if((c = cpass()) == NO_MORE)
				return;
			tkc[tki] = c;
		}
		tki = 0;
		if(tkvalid(xc = tkbuild(tkc[0], tkc[1])) &&
		   tkvalid(yc = tkbuild(tkc[2], tkc[3]))) {
			tkwait();
			TKADDR->x = xc;
			TKADDR->y = yc;
			TKADDR->csr |= INTENSIFY|IENABLE;
		}
	}
}

tkvalid(coord)
	register int coord;
{
	return(coord <= COORDMASK && coord >= ~COORDMASK);
}

tkwait() {	/* wait for READY */ 
	spl5();
	while(!(TKADDR->csr&READY))
		sleep(TKADDR, TKPRI);
	spl0();
}

tkint(dev) {
	TKADDR->csr &= ~IENABLE;
	wakeup(TKADDR);
}