;--------------------------------------------------------------------------
;  labs.s
;
;  Copyright (C) 2020, Tony Pavlov
;
;  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.
;--------------------------------------------------------------------------

        .module labs

        .area   _HOME

;long labs(long num)
_labs::
        lda     HL, 2(SP)
        ld      A, (HL+)
        ld      E, A
        ld      A, (HL+)
        ld      D, A
        ld      A, (HL+)
        ld      H, (HL)
        ld      L, A            ; DEHL = num

.labs::
        ld      A, H
        add     A, A
        ret     NC

1$:
        ld      A, E
        cpl
        add     #1
        ld      E, A

        ld      A, D
        cpl
        adc     #0
        ld      D, A

        ld      A, L
        cpl
        adc     #0
        ld      L, A

        ld      A, H
        cpl
        adc     #0
        ld      H, A

        ret 
