| /* Copyright (C) 1998 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Code contributed by Matthew Wilcox <willy@odie.barnet.ac.uk> |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #include <features.h> |
| #include <endian.h> |
| #include <sys/syscall.h> |
| #include <bits/arm_asm.h> |
| |
| /* size_t strlen(const char *S) |
| * entry: r0 -> string |
| * exit: r0 = len |
| */ |
| |
| .text |
| .global strlen |
| .type strlen,%function |
| .align 4 |
| |
| #if defined(THUMB1_ONLY) |
| /* A simple implementation for when the ARM implementation can't be used. */ |
| .thumb_func |
| strlen: |
| mov r2, #0 |
| 1: |
| ldrb r1, [r0, r2] |
| add r2, r2, #1 |
| cmp r1, #0 |
| bne 1b |
| sub r0, r2, #1 |
| bx lr |
| #else |
| strlen: |
| bic r1, r0, $3 @ addr of word containing first byte |
| ldr r2, [r1], $4 @ get the first word |
| ands r3, r0, $3 @ how many bytes are duff? |
| rsb r0, r3, $0 @ get - that number into counter. |
| beq Laligned @ skip into main check routine if no |
| @ more |
| #if __BYTE_ORDER == __BIG_ENDIAN |
| orr r2, r2, $0xff000000 @ set this byte to non-zero |
| subs r3, r3, $1 @ any more to do? |
| IT(t, gt) |
| orrgt r2, r2, $0x00ff0000 @ if so, set this byte |
| subs r3, r3, $1 @ more? |
| IT(t, gt) |
| orrgt r2, r2, $0x0000ff00 @ then set. |
| #else |
| orr r2, r2, $0x000000ff @ set this byte to non-zero |
| subs r3, r3, $1 @ any more to do? |
| IT(t, gt) |
| orrgt r2, r2, $0x0000ff00 @ if so, set this byte |
| subs r3, r3, $1 @ more? |
| IT(t, gt) |
| orrgt r2, r2, $0x00ff0000 @ then set. |
| #endif |
| Laligned: @ here, we have a word in r2. Does it |
| tst r2, $0x000000ff @ contain any zeroes? |
| IT(tttt, ne) |
| tstne r2, $0x0000ff00 @ |
| tstne r2, $0x00ff0000 @ |
| tstne r2, $0xff000000 @ |
| addne r0, r0, $4 @ if not, the string is 4 bytes longer |
| IT(t, ne) |
| ldrne r2, [r1], $4 @ and we continue to the next word |
| bne Laligned @ |
| Llastword: @ drop through to here once we find a |
| #if __BYTE_ORDER == __BIG_ENDIAN |
| tst r2, $0xff000000 @ word that has a zero byte in it |
| IT(tttt, ne) |
| addne r0, r0, $1 @ |
| tstne r2, $0x00ff0000 @ and add up to 3 bytes on to it |
| addne r0, r0, $1 @ |
| tstne r2, $0x0000ff00 @ (if first three all non-zero, 4th |
| IT(t, ne) |
| addne r0, r0, $1 @ must be zero) |
| #else |
| tst r2, $0x000000ff @ |
| IT(tttt, ne) |
| addne r0, r0, $1 @ |
| tstne r2, $0x0000ff00 @ and add up to 3 bytes on to it |
| addne r0, r0, $1 @ |
| tstne r2, $0x00ff0000 @ (if first three all non-zero, 4th |
| IT(t, ne) |
| addne r0, r0, $1 @ must be zero) |
| #endif |
| #if defined(__USE_BX__) |
| bx lr |
| #else |
| mov pc,lr |
| #endif |
| #endif |
| |
| .size strlen,.-strlen |
| |
| libc_hidden_def(strlen) |