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;--------------------------------------------------------------------------
; mulchar.s
;
; Copyright (c) 2017, Philipp Klaus Krause
;
; 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
; unsigned char x unsigned char multiplication is done by code generation.
.globl __mulsuchar
.globl __muluschar
.globl __mulschar
; operands have different sign
__mulsuchar:
ld hl,#2+1
ld b, h
add hl,sp
ld e,(hl)
dec hl
ld c,(hl)
jr signexte
__muluschar:
ld hl,#2
ld b, h
add hl,sp
ld e,(hl)
inc hl
ld c,(hl)
jr signexte
__mulschar:
ld hl,#2+1
add hl,sp
ld e,(hl)
dec hl
ld c,(hl)
;; Need to sign extend before going in.
ld a,c
rla
sbc a,a
ld b,a
signexte:
ld a,e
rla
sbc a,a
ld d,a
jp __mul16
|
