gbdk-2020 | GameBoy Development Kit |
| download: https://git.y1.nz/archives/gbdk.tar.gz | |
| README | Files | Log | Refs | LICENSE |
gbdk-lib/libc/asm/z80/mulchar.s
1 ;--------------------------------------------------------------------------
2 ; mulchar.s
3 ;
4 ; Copyright (c) 2017-2021, Philipp Klaus Krause
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 .area _CODE
30
31 ; unsigned char x unsigned char multiplication is done by code generation.
32
33 .globl __mulsuchar
34 .globl __muluschar
35 .globl __mulschar
36
37 ; operands have different sign
38
39 __muluschar:
40 ld e, a
41 ld c, l
42 ld b, #0
43
44 jr signexte
45
46 __mulsuchar:
47 ld c, a
48 ld b, #0
49 ld e, l
50
51 jr signexte
52
53 __mulschar:
54 ld e, l
55 ld c, a
56
57 ;; Need to sign extend before going in.
58 rla
59 sbc a, a
60 ld b, a
61 signexte:
62 ld a, e
63 rla
64 sbc a, a
65 ld d, a
66
67 jp __mul16
68
This webpage is intended to be an accessible preview of this repository. To get a fuller picture, clone it and use the git CLI.