gbdk-2020 | GameBoy Development Kit |
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gbdk-lib/libc/asm/mos6502/_memcmp.s
1 ;-------------------------------------------------------------------------
2 ; memcmp.s - standarc C library
3 ;
4 ; Copyright (C) 2003, Ullrich von Bassewitz
5 ; Copyright (C) 2009, Christian Krueger
6 ; Copyright (C) 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 memcmp
32
33 ;--------------------------------------------------------
34 ; exported symbols
35 ;--------------------------------------------------------
36 .globl _memcmp_PARM_2
37 .globl _memcmp_PARM_3
38 .globl _memcmp
39
40 ;--------------------------------------------------------
41 ; overlayable function parameters in zero page
42 ;--------------------------------------------------------
43 .area OSEG (PAG, OVR)
44 _memcmp_PARM_2:
45 .ds 2
46 _memcmp_PARM_3:
47 .ds 2
48
49 ;--------------------------------------------------------
50 ; local aliases
51 ;--------------------------------------------------------
52 .define s1 "DPTR"
53 .define s2 "_memcmp_PARM_2"
54 .define count "_memcmp_PARM_3"
55
56 ;--------------------------------------------------------
57 ; code
58 ;--------------------------------------------------------
59 .area _CODE
60
61 ;--------------------------------------------------------
62 ; int memcmp (int *s1, int *s2, int count)
63 ;--------------------------------------------------------
64
65 _memcmp:
66 sta *s1+0
67 stx *s1+1
68 ldy #0
69 ldx *count+1
70 beq endhi
71 hiloop:
72 lda [s1],y
73 cmp [s2],y
74 bne noteq
75 iny
76 bne hiloop
77 inc *s1+1
78 inc *s2+1
79 dex
80 bne hiloop
81 endhi:
82 ldx *count+0
83 beq end
84 loloop:
85 lda [s1],y
86 cmp [s2],y
87 bne noteq
88 iny
89 dex
90 bne loloop
91 end:
92 txa
93 rts
94 noteq:
95 bcs L2
96 ldx #0xFF
97 rts
98 L2:
99 ldx #0x01
100 rts
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