gbdk-2020 | GameBoy Development Kit |
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gbdk-lib/libc/asm/mos6502/memcpy.s
1 ;-------------------------------------------------------------------------
2 ; memcpy.s - standarc C library
3 ;
4 ; Copyright (C) 2003, Ullrich von Bassewitz
5 ; Copyright (C) 2009, Christian Krueger
6 ; Copyright (C) 2022-2023, Gabriele Gorla
7 ;
8 ; This library is free software; you can redistribute it and/or modify it
9 ; under the terms of the GNU General Public License as published by the
10 ; Free Software Foundation; either version 2, or (at your option) any
11 ; later version.
12 ;
13 ; This library is distributed in the hope that it will be useful,
14 ; but WITHOUT ANY WARRANTY; without even the implied warranty of
15 ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 ; GNU General Public License for more details.
17 ;
18 ; You should have received a copy of the GNU General Public License
19 ; along with this library; see the file COPYING. If not, write to the
20 ; Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
21 ; MA 02110-1301, USA.
22 ;
23 ; As a special exception, if you link this library with other files,
24 ; some of which are compiled with SDCC, to produce an executable,
25 ; this library does not by itself cause the resulting executable to
26 ; be covered by the GNU General Public License. This exception does
27 ; not however invalidate any other reasons why the executable file
28 ; might be covered by the GNU General Public License.
29 ;-------------------------------------------------------------------------
30
31 ; .module __memcpy
32
33 ;--------------------------------------------------------
34 ; exported symbols
35 ;--------------------------------------------------------
36 .globl ___memcpy_PARM_2
37 .globl ___memcpy_PARM_3
38 .globl ___memcpy
39 .globl _memcpy_PARM_2
40 .globl _memcpy_PARM_3
41 .globl _memcpy
42
43 ;--------------------------------------------------------
44 ; overlayable function parameters in zero page
45 ;--------------------------------------------------------
46 .area OSEG (PAG, OVR)
47 _memcpy_PARM_2:
48 ___memcpy_PARM_2:
49 .ds 2
50 _memcpy_PARM_3:
51 ___memcpy_PARM_3:
52 .ds 2
53
54 ;--------------------------------------------------------
55 ; local aliases
56 ;--------------------------------------------------------
57 .define save "REGTEMP+0"
58 .define dst "DPTR"
59 .define src "___memcpy_PARM_2"
60 .define count "___memcpy_PARM_3"
61
62 ;--------------------------------------------------------
63 ; code
64 ;--------------------------------------------------------
65 .area _CODE
66
67 _memcpy:
68 ___memcpy:
69 sta *save+0
70 stx *save+1
71 sta *dst+0
72 stx *dst+1
73
74 ldy #0
75 ldx *count+1
76 beq 00002$
77 00001$:
78 lda [src],y
79 sta [dst],y
80 iny
81 lda [src],y
82 sta [dst],y
83 iny
84 bne 00001$
85 inc *src+1
86 inc *dst+1
87 dex
88 bne 00001$
89 00002$:
90 ldx *count+0
91 beq 00004$
92 00003$:
93 lda [src],y
94 sta [dst],y
95 iny
96 dex
97 bne 00003$
98 00004$:
99 lda *save+0
100 ldx *save+1
101 rts
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