Add original unix v6

source/s4/atof.s

@@ -0,0 +1,130 @@
+/ C library -- ascii to floating
+
+/	f = atof(p)
+/	char *p;
+
+ldfps = 170100^tst
+stfps = 170200^tst
+
+.globl	_atof
+
+.globl	csv, cret
+
+_atof:
+	jsr	r5,csv
+	stfps	-(sp)
+	ldfps	$200
+	movf	fr1,-(sp)
+	clr	-(sp)
+	clrf	fr0
+	clr	r2
+	mov	4(r5),r3
+1:
+	movb	(r3)+,r0
+	cmp	$' ,r0
+	beq	1b
+	cmpb	r0,$'-
+	bne	2f
+	inc	(sp)
+1:
+	movb	(r3)+,r0
+2:
+	sub	$'0,r0
+	cmp	r0,$9.
+	bhi	2f
+	jsr	pc,digit
+		br 1b
+	inc	r2
+	br	1b
+2:
+	cmpb	r0,$'.-'0
+	bne	2f
+1:
+	movb	(r3)+,r0
+	sub	$'0,r0
+	cmp	r0,$9.
+	bhi	2f
+	jsr	pc,digit
+		dec r2
+	br	1b
+2:
+	cmpb	r0,$'E-'0
+	beq	3f
+	cmpb	r0,$'e-'0
+	bne	1f
+3:
+	clr	r4
+	clr	r1
+	cmpb	(r3),$'-
+	bne	3f
+	inc	r4
+	inc	r3
+3:
+	movb	(r3)+,r0
+	sub	$'0,r0
+	cmp	r0,$9.
+	bhi	3f
+	mul	$10.,r1
+	add	r0,r1
+	br	3b
+3:
+	tst	r4
+	bne	3f
+	neg	r1
+3:
+	sub	r1,r2
+1:
+	movf	$one,fr1
+	mov	r2,-(sp)
+	beq	2f
+	bgt	1f
+	neg	r2
+1:
+	cmp	r2,$38.
+	blos	1f
+	clrf	fr0
+	tst	(sp)+
+	bmi	out
+	movf	$huge,fr0
+	br	out
+1:
+	mulf	$ten,fr1
+	sob	r2,1b
+2:
+	tst	(sp)+
+	bge	1f
+	divf	fr1,fr0
+	br	2f
+1:
+	mulf	fr1,fr0
+	cfcc
+	bvc	2f
+	movf	$huge,fr0
+2:
+out:
+	tst	(sp)+
+	beq	1f
+	negf	fr0
+1:
+	movf	(sp)+,fr1
+	ldfps	(sp)+
+	jmp	cret
+/
+/
+digit:
+	cmpf	$big,fr0
+	cfcc
+	blt	1f
+	mulf	$ten,fr0
+	movif	r0,fr1
+	addf	fr1,fr0
+	rts	pc
+1:
+	add	$2,(sp)
+	rts	pc
+/
+/
+one	= 40200
+ten	= 41040
+big	= 56200
+huge	= 77777