Add original unix v6

source/fort/rt1/ierr.s

@@ -0,0 +1,69 @@
+/
+/
+
+/ catch runtime errors:
+/ if (ierror(errno)) goto place
+/ on call, returns 0
+/ on occurrence of error, returns non-zero
+
+.globl	ierror.
+.globl	erret
+
+.globl	rerr
+.globl	retrn
+
+ierror.:zero
+	.+2
+	mov	2(r3),r0
+	mov	2(r0),r1
+	mov	$errbuf,r0
+1:
+	cmp	r0,cerrp
+	blo	2f
+	cmp	cerrp,$eerbuf
+	blo	3f
+	jsr	r5,rerr; 120.
+3:
+	add	$8,cerrp
+	br	1f
+2:
+	cmp	r1,(r0)
+	beq	1f
+	add	$8,r0
+	br	1b
+1:
+	mov	r1,(r0)+
+	mov	r3,(r0)+
+	mov	2(sp),(r0)+
+	mov	4(sp),(r0)+
+	jmp	retrn
+
+.data
+erret:
+	jmp	9f
+.text
+9:
+	mov	$errbuf,r0
+	cmp	(r0),r1
+	beq	1f
+	add	$8,r0
+	cmp	r0,cerrp
+	blo	1b
+	rts	pc
+1:
+	add	$8,r0
+	mov	-(r0),-(sp)
+	mov	-(r0),-(sp)
+	mov	$one,-(sp)
+	mov	-(r0),r3
+	jmp	retrn
+
+.data
+one:	77777; 177777
+zero:	0; 0
+
+cerrp:	errbuf
+
+.bss
+errbuf:	.=.+50
+eerbuf: