gbdk-2020 | GameBoy Development Kit |
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gbdk-lib/libc/asm/mos6502/_strcpy.s
1 ;-------------------------------------------------------------------------
2 ; _strcpy.s - standard C library function
3 ;
4 ; Copyright (C) 1998, Ullrich von Bassewitz
5 ; Copyright (C) 2022, Gabriele Gorla
6 ;
7 ; This library is free software; you can redistribute it and/or modify it
8 ; under the terms of the GNU General Public License as published by the
9 ; Free Software Foundation; either version 2, or (at your option) any
10 ; later version.
11 ;
12 ; This library is distributed in the hope that it will be useful,
13 ; but WITHOUT ANY WARRANTY; without even the implied warranty of
14 ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 ; GNU General Public License for more details.
16 ;
17 ; You should have received a copy of the GNU General Public License
18 ; along with this library; see the file COPYING. If not, write to the
19 ; Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
20 ; MA 02110-1301, USA.
21 ;
22 ; As a special exception, if you link this library with other files,
23 ; some of which are compiled with SDCC, to produce an executable,
24 ; this library does not by itself cause the resulting executable to
25 ; be covered by the GNU General Public License. This exception does
26 ; not however invalidate any other reasons why the executable file
27 ; might be covered by the GNU General Public License.
28 ;-------------------------------------------------------------------------
29
30 .module _strcpy
31
32 ;--------------------------------------------------------
33 ; exported symbols
34 ;--------------------------------------------------------
35 .globl _strcpy_PARM_2
36 .globl _strcpy
37
38 ;--------------------------------------------------------
39 ; overlayable function parameters in zero page
40 ;--------------------------------------------------------
41 .area OSEG (PAG, OVR)
42 _strcpy_PARM_2:
43 .ds 2
44
45 ;--------------------------------------------------------
46 ; local aliases
47 ;--------------------------------------------------------
48 .define _src "_strcpy_PARM_2"
49 .define _dst "DPTR"
50
51 ;--------------------------------------------------------
52 ; code
53 ;--------------------------------------------------------
54 .area _CODE
55
56 _strcpy:
57 sta *_dst+0
58 stx *_dst+1
59
60 ldy #0
61 cpy_loop:
62 lda [_src],y
63 sta [_dst],y
64 beq end
65 iny
66 bne cpy_loop
67 inc *_src+1
68 inc *_dst+1
69 bne cpy_loop
70 ; jmp cpy_loop
71 end:
72 lda *_dst+0
73 rts
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