;----------------------------------------------------------------
; This is a module in the PLIUTIL library
;
; This module shifts bit(16) strings around
;
; Written by  Richard Holmes    10-12-84
; Last Update Richard Holmes    10-12-84
;----------------------------------------------------------------
;
	name	'shift'
	public	shl16,shr16
	extrn	getp1,getp2
;
; Return a bit 16 shifted left by the bin(15)
;
shl16:
	call 	fetch
	ora	a
shl$loop:
	mov	a,l
	ral
	mov	l,a
	mov	a,h
	ral
	mov	h,a
	dcx	d
	mov	a,e
	ora	d
	jnz	shl$loop
	ret
;
shr16:
	call	fetch
	ora	a		; Clear initial carry flag
shr$loop:
	mov	a,h		; top 8
	rar			; move right
	mov	h,a
	mov	a,l
	rar			; move the bit in
	mov	l,a
;
	dcx	d
	mov	a,e
	ora	d		; set Zero, clear carry flags
	jnz	shr$loop
	ret
;
fetch:
	mov	e,m
	inx	h
	mov	d,m		; de -> parameter 1
	inx	h
	push	h		; save
	xchg			; hl -> parameter
	mov	e,m
	inx	h
	mov	d,m
	pop	h		; restore address
	mov	c,m
	inx	h
	mov	b,m		; Get second address
	ldax	b
	mov	l,a
	inx	b
	ldax	b
	mov	h,a
	xchg			; make HL first parameter
	ret
;
	end