gbdk-2020 | GameBoy Development Kit |
| download: https://git.y1.nz/archives/gbdk.tar.gz | |
| README | Files | Log | Refs | LICENSE |
gbdk-lib/libc/asm/sm83/labs.s
1 ;--------------------------------------------------------------------------
2 ; labs.s
3 ;
4 ; Copyright (C) 2020, Tony Pavlov
5 ;
6 ; This library is free software; you can redistribute it and/or modify it
7 ; under the terms of the GNU General Public License as published by the
8 ; Free Software Foundation; either version 2, or (at your option) any
9 ; later version.
10 ;
11 ; This library is distributed in the hope that it will be useful,
12 ; but WITHOUT ANY WARRANTY; without even the implied warranty of
13 ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 ; GNU General Public License for more details.
15 ;
16 ; You should have received a copy of the GNU General Public License
17 ; along with this library; see the file COPYING. If not, write to the
18 ; Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
19 ; MA 02110-1301, USA.
20 ;
21 ; As a special exception, if you link this library with other files,
22 ; some of which are compiled with SDCC, to produce an executable,
23 ; this library does not by itself cause the resulting executable to
24 ; be covered by the GNU General Public License. This exception does
25 ; not however invalidate any other reasons why the executable file
26 ; might be covered by the GNU General Public License.
27 ;--------------------------------------------------------------------------
28
29 .module labs
30
31 .area _HOME
32
33 ;long labs(long num)
34 _labs::
35 lda HL, 2(SP)
36 ld A, (HL+)
37 ld E, A
38 ld A, (HL+)
39 ld D, A
40 ld A, (HL+)
41 ld H, (HL)
42 ld L, A ; DEHL = num
43
44 .labs::
45 ld A, H
46 add A, A
47 ret NC
48
49 1$:
50 ld A, E
51 cpl
52 add #1
53 ld E, A
54
55 ld A, D
56 cpl
57 adc #0
58 ld D, A
59
60 ld A, L
61 cpl
62 adc #0
63 ld L, A
64
65 ld A, H
66 cpl
67 adc #0
68 ld H, A
69
70 ret
This webpage is intended to be an accessible preview of this repository. To get a fuller picture, clone it and use the git CLI.