; Listing 22.2.  L22-2.ASM

ClearS	proc	near
	push	bp				;save caller's BP
	mov	bp,sp				;point to stack frame
	cmp	word ptr [bp].BufSeg,0		;skip the fill if a null
	jne	Start				; pointer is passed
	cmp	word ptr [bp].BufOfs,0	
	je	Bye
Start: cld						;make STOSW count up
	mov	ax,[bp].Attrib			;load AX with attribute parameter
	and	ax,0ff00h				;prepare for merging with fill char
	mov	bx,[bp].Filler			;load BX with fill char
	and	bx,0ffh				;prepare for merging with attribute
	or	ax,bx				;combine attribute and fill char
	mov	di,[bp].BufOfs			;load DI with target buffer offset
	mov	es,[bp].BufSeg			;load ES with target buffer segment
	mov	cx,[bp].BufSize			;load CX with buffer size
	rep	stosw				;fill the buffer
Bye:
	pop	bp				;restore caller's BP
	ret	EndMrk-RetAddr-2			;return, clearing the parms from the stack
ClearS	endp
