Add original unix v6

source/s1/form2.s

@@ -0,0 +1,92 @@
+/	scan
+/	r1 = pointer to input header
+/	r0 = pointer to output header
+/	switch = 0 real output
+/		not 0  output to r0
+scan:
+	mov	r0,-(sp)
+	mov	r1,-(sp)
+
+1:
+	mov	(sp),r1
+	jsr	pc,getchar
+	bes	5f
+	cmpb	r0,$'\\
+	beq	3f
+	cmpb	r0,$'\[
+	beq	4f
+	cmpb	r0,$'\{
+	beq	4f
+	cmpb	r0,$'\]
+	beq	1f
+	cmpb	r0,$'\}
+	beq	7f
+	cmpb	r0,$'\n
+	bne	6f
+	jsr	pc,lookchar
+	bes	5f
+	movb	$'\n,r0
+6:
+	tst	switch
+	beq	2f
+	mov	2(sp),r1
+	jsr	pc,putchar
+	br	1b
+2:
+	jsr	r5,putc
+	br	1b
+3:
+	jsr	pc,getchar
+	br	6b
+/	have [ or {
+4:
+	mov	r(r1),-(sp)
+	jsr	pc,getchar
+	bes	1f
+	cmpb	r0,$'0
+	blt	4f
+	cmpb	r0,$'9
+	bgt	4f
+	jsr	pc,getchar
+	cmpb	r0,$'\]
+	beq	3f
+	cmpb	r0,$'\}
+	beq	3f
+
+4:
+	mov	(sp)+,r(r1)
+	mov	2(sp),r0
+	jsr	pc,esub
+	mov	r1,(sp)
+	mov	r0,2(sp)
+	br	1b
+
+/	have arg
+3:
+	tst	switch
+	beq	2f
+	mov	opointer,r1
+	mov	4(sp),r0
+	jsr	pc,putword
+	mov	2(sp),r1
+2:
+	mov	(sp)+,r(r1)
+	jsr	pc,getchar
+	inc	r(r1)	/skip ]
+	jsr	pc,earg
+	br	1b
+
+5:
+	tst	argf
+	bne	1f
+	mov	ipointer,r1
+	jsr	pc,pop
+	bes	1f
+	mov	r0,(sp)
+	br	1b
+7:
+	inc	curlyf
+1:
+	mov	(sp)+,r1
+	mov	(sp)+,r0
+	rts	pc