Add original unix v6

source/fort/rt2/openrw.s

@@ -0,0 +1,51 @@
+/
+/
+
+/ openr, openw--
+/
+/ call open(r|w) (string, iunit)
+/   or,
+/ call open(r|w) (argno, iunit)
+/ where argno is an argument number (0 is command name)
+
+.globl	openr.
+.globl	openw.
+
+.globl	utable
+.globl	btable
+.globl	ftable
+.globl	getbuf
+.globl	fopen
+.globl	fcreat
+
+openr.:	temp
+	.+2
+	mov	pc,-(sp)
+	br	1f
+
+openw.:	temp
+	.+2
+	clr	-(sp)
+1:
+	mov	4(r3),r1
+	mov	2(r1),r1
+	jsr	r5,chkunit
+	tstb	utable(r1)
+	beq	1f
+	jsr	r5,rerr; 101.
+	sys	exit
+1:
+	jsr	r5,getbuf
+	mov	2(r3),r0
+	mov	2(r0),r0
+	cmp	r0,$32.
+	bhi	1f
+	cmp	r0,*argp
+	bhi	err
+	asl	r0
+	add	argp,r0
+	br	2f
+1:
+	tst	(sp)+
+	beq	1f
+	movb	$1,utable(r1)