.NLIST	TOC,SYM
.TITLE	$DMUL
.SBTTL	ULBLIB 036	- Double Precision Multiply
.IDENT	\V01.00\
.PSECT	.LIBC.
.ENABL	LC,GBL

; Copyright (c) 1998 by Mentec, Inc., Nashua, NH.
; All rights reserved
;
; This software is furnished under a license for use only on a
; single computer system and  may  be  copied  only  with  the
; inclusion of the above copyright notice.  This software,  or
; any other copies thereof, may not be provided  or  otherwise
; made available to any other person except for  use  on  such
; system and to one who agrees to these license  terms.  Title
; to  and  ownership of the software shall at all times remain
; in Mentec, Inc.
;
; The information in this document is subject to change without
; notice and should not be construed as a commitment by Digital
; Equipment Corporation, or Mentec, Inc.
;
; Digital and Mentec  assume  no  responsibility for the use or
; reliability of its software on equipment which is not supplied
; by Digital  or Mentec,  and listed  in the  Software  Product
; Description.
;+
; $DMUL
; This routine multiplies a double precision multiplicand by a single
; precision multiplier and yields a double precision result.  All are
; unsigned.
;
;	R0	= single precision multiplier
;	R2	= hi-order part of double precision multiplicand
;	R3	= lo-order part of double precision multiplicand
;
;	JSR	PC,$DMUL
;
;	C-bit	= 0
;	R0	= hi-order part of double precision multiplicand
;	R1	= lo-order part of double precision multiplicand
;	R2,R3	= random
;-

$DMUL::
	MOV	R0,-(SP)	;Single precision multiplier
	CLR	R0		;Initialize the result
	CLR	R1		;Both words
1$:	TST	(SP)		;If remaining multiplier is zero,
	BEQ	3$		; then all through
	ROR	(SP)		;If next bit is a one,
	BCC	2$		;
	ADD	R3,R1		; then add multiplicand to result
	ADC	R0		;Add in carry
	ADD	R2,R0		;Add in hi-order part
2$:	ASL	R3		;In either case, double the multiplicand,
	ROL	R2		;
	BR	1$		; and see if any more multiplier
3$:	TST	(SP)+		;Clean up the stack, return C-bit = 0
	RETURN
.END