Add original unix v6

source/s5/nargs.s

@@ -0,0 +1,62 @@
+/ C library -- nargs
+
+/ WARNING: this routine does not work
+/ with user I&D space separate.
+/ Moreover, due to a design botch in
+/ the 11/45, it cannot be made to work
+/ by adding mfpi instructions.
+
+.globl	_nargs
+
+_nargs:
+	mov	r5,-(sp)
+	mov	2(r5),r1		/ pc of caller of caller
+	mov	sp,r5
+	clr	r0
+	cmp	-4(r1),jsrsd
+	bne	8f
+	mov	$2,r0
+8:
+	cmp	(r1),tsti
+	bne	1f
+	add	$2,r0
+	br	2f
+1:
+	cmp	(r1),cmpi
+	bne	1f
+	add	$4,r0
+	br	2f
+1:
+	cmp	(r1),addi
+	bne	1f
+	add	2(r1),r0
+	br	2f
+1:
+	cmp	(r1),jmpi
+	bne	1f
+	add	2(r1),r1
+	add	$4,r1
+	br	8b
+1:
+	cmpb	1(r1),bri+1
+	bne	2f
+	mov	r0,-(sp)
+	mov	(r1),r0
+	swab	r0
+	ash	$-7,r0
+	add	r0,r1
+	add	$2,r1
+	mov	(sp)+,r0
+	br	8b
+2:
+	asr	r0
+	mov	(sp)+,r5
+	rts	pc
+
+.data
+jsrsd:	jsr	pc,*$0
+tsti:	tst	(sp)+
+cmpi:	cmp	(sp)+,(sp)+
+addi:	add	$0,sp
+jmpi:	jmp	0
+bri:	br	.