;--------------------------------------------------------------------------
;  mulchar.s
;
;  Copyright (C) 2000, Michael Hope
;
;  This library is free software; you can redistribute it and/or modify it
;  under the terms of the GNU General Public License as published by the
;  Free Software Foundation; either version 2, or (at your option) any
;  later version.
;
;  This library is distributed in the hope that it will be useful,
;  but WITHOUT ANY WARRANTY; without even the implied warranty of
;  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;  GNU General Public License for more details.
;
;  You should have received a copy of the GNU General Public License 
;  along with this library; see the file COPYING. If not, write to the
;  Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
;   MA 02110-1301, USA.
;
;  As a special exception, if you link this library with other files,
;  some of which are compiled with SDCC, to produce an executable,
;  this library does not by itself cause the resulting executable to
;  be covered by the GNU General Public License. This exception does
;  not however invalidate any other reasons why the executable file
;   might be covered by the GNU General Public License.
;--------------------------------------------------------------------------

.area   _CODE

.globl	__mulint

__mulint:
	pop     af
	pop     bc		;kio 2014-11-16
	pop     de
	push    de
	push    bc		;kio 2014-11-16
	push    af
	;; Fall through

	;; Parameters:
	;; hl, de (left, right irrelevant)
;	ld		b,h		;removed kio 2014-11-16
;	ld		c,l		;removed kio 2014-11-16

	;; 16-bit multiplication
	;;
	;; Entry conditions
	;; bc = multiplicand
	;; de = multiplier
	;;
	;; Exit conditions
	;; hl = less significant word of product
	;;
	;; Register used: AF,BC,DE,HL
	
__mul16::
	xor		a,a
	ld		l,a
	or		a,b
	ld		b,16

	;; Optimise for the case when this side has 8 bits of data or
	;; less.  This is often the case with support address calls.
	jr		nz,2$
	ld		b,8
	ld		a,c

	;; Taken from z88dk, which borrowed from the Spectrum rom.
1$:	add		hl,hl
2$:	rl		c
	rla                     ;DLE 27/11/98
	jr		nc,3$
	add		hl,de
3$:	djnz	1$
	ret