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a72cc2b2 | 1 | /* Optimized strlen implementation for PowerPC476. |
688903eb | 2 | Copyright (C) 2010-2018 Free Software Foundation, Inc. |
a72cc2b2 LM |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
ab84e3ff PE |
16 | License along with the GNU C Library. If not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
a72cc2b2 LM |
18 | |
19 | #include <sysdep.h> | |
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20 | |
21 | /* strlen | |
22 | ||
23 | Register Use | |
24 | r3:source address and return length of string | |
25 | r4:byte counter | |
26 | ||
27 | Implementation description | |
28 | Load 2 words at a time and count bytes, if we find null we subtract one from | |
29 | the count and return the count value. We need to subtract one because | |
30 | we don't count the null character as a byte. */ | |
31 | ||
b5510883 | 32 | EALIGN (strlen,5,0) |
a72cc2b2 LM |
33 | neg r7,r3 |
34 | clrlwi. r8,r7,29 | |
35 | addi r4,0,0 | |
36 | beq L(byte_count_loop) | |
37 | mtctr r8 | |
38 | ||
39 | L(loop): | |
40 | lbz r5,0(r3) | |
41 | cmpi cr5,r5,0x0 | |
42 | addi r3,r3,0x1 | |
43 | addi r4,r4,0x1 | |
44 | beq cr5,L(end_strlen) | |
45 | bdnz L(loop) | |
46 | ||
47 | L(byte_count_loop): | |
48 | lwz r5,0(r3) | |
49 | lwz r6,4(r3) | |
50 | dlmzb. r12,r5,r6 | |
51 | add r4,r4,r12 | |
52 | bne L(end_strlen) | |
53 | lwz r5,8(r3) | |
54 | lwz r6,12(r3) | |
55 | dlmzb. r12,r5,r6 | |
56 | add r4,r4,r12 | |
57 | bne L(end_strlen) | |
58 | lwz r5,16(r3) | |
59 | lwz r6,20(r3) | |
60 | dlmzb. r12,r5,r6 | |
61 | add r4,r4,r12 | |
62 | bne L(end_strlen) | |
63 | lwz r5,24(r3) | |
64 | lwz r6,28(r3) | |
65 | addi r3,r3,0x20 | |
66 | dlmzb. r12,r5,r6 | |
67 | add r4,r4,r12 | |
68 | bne L(end_strlen) | |
69 | b L(byte_count_loop) | |
70 | ||
71 | L(end_strlen): | |
72 | addi r3,r4,-1 | |
73 | blr | |
b5510883 | 74 | END (strlen) |
a72cc2b2 | 75 | libc_hidden_builtin_def (strlen) |