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1 | /* Copyright (C) 1998 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. | |
3 | Code contributed by Matthew Wilcox <willy@odie.barnet.ac.uk> | |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
3214b89b AJ |
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. | |
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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 | |
3214b89b | 13 | Lesser General Public License for more details. |
42d5b281 | 14 | |
3214b89b AJ |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, write to the Free | |
17 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
18 | 02111-1307 USA. */ | |
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19 | |
20 | #include <sysdep.h> | |
21 | ||
22 | /* size_t strlen(const char *S) | |
23 | * entry: r0 -> string | |
24 | * exit: r0 = len | |
25 | */ | |
26 | ||
27 | ENTRY(strlen) | |
28 | bic r1, r0, $3 @ addr of word containing first byte | |
29 | ldr r2, [r1], $4 @ get the first word | |
30 | ands r3, r0, $3 @ how many bytes are duff? | |
31 | rsb r0, r3, $0 @ get - that number into counter. | |
32 | beq Laligned @ skip into main check routine if no | |
33 | @ more | |
69069c4a | 34 | #ifdef __ARMEB__ |
42d5b281 UD |
35 | orr r2, r2, $0xff000000 @ set this byte to non-zero |
36 | subs r3, r3, $1 @ any more to do? | |
37 | orrgt r2, r2, $0x00ff0000 @ if so, set this byte | |
38 | subs r3, r3, $1 @ more? | |
39 | orrgt r2, r2, $0x0000ff00 @ then set. | |
69069c4a UD |
40 | #else |
41 | orr r2, r2, $0x000000ff @ set this byte to non-zero | |
42 | subs r3, r3, $1 @ any more to do? | |
43 | orrgt r2, r2, $0x0000ff00 @ if so, set this byte | |
44 | subs r3, r3, $1 @ more? | |
45 | orrgt r2, r2, $0x00ff0000 @ then set. | |
46 | #endif | |
42d5b281 UD |
47 | Laligned: @ here, we have a word in r2. Does it |
48 | tst r2, $0x000000ff @ contain any zeroes? | |
49 | tstne r2, $0x0000ff00 @ | |
50 | tstne r2, $0x00ff0000 @ | |
51 | tstne r2, $0xff000000 @ | |
52 | addne r0, r0, $4 @ if not, the string is 4 bytes longer | |
53 | ldrne r2, [r1], $4 @ and we continue to the next word | |
54 | bne Laligned @ | |
55 | Llastword: @ drop through to here once we find a | |
56 | tst r2, $0x000000ff @ word that has a zero byte in it | |
57 | addne r0, r0, $1 @ | |
58 | tstne r2, $0x0000ff00 @ and add up to 3 bytes on to it | |
59 | addne r0, r0, $1 @ | |
60 | tstne r2, $0x00ff0000 @ (if first three all non-zero, 4th | |
61 | addne r0, r0, $1 @ must be zero) | |
62 | RETINSTR(mov,pc,lr) | |
63 | END(strlen) |