| /* Optimized strlen implementation for PowerPC476. |
| Copyright (C) 2010-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| 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, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <sysdep.h> |
| |
| /* strlen |
| |
| Register Use |
| r3:source address and return length of string |
| r4:byte counter |
| |
| Implementation description |
| Load 2 words at a time and count bytes, if we find null we subtract one from |
| the count and return the count value. We need to subtract one because |
| we don't count the null character as a byte. */ |
| |
| EALIGN (strlen,5,0) |
| neg r7,r3 |
| clrlwi. r8,r7,29 |
| addi r4,0,0 |
| beq L(byte_count_loop) |
| mtctr r8 |
| |
| L(loop): |
| lbz r5,0(r3) |
| cmpi cr5,r5,0x0 |
| addi r3,r3,0x1 |
| addi r4,r4,0x1 |
| beq cr5,L(end_strlen) |
| bdnz L(loop) |
| |
| L(byte_count_loop): |
| lwz r5,0(r3) |
| lwz r6,4(r3) |
| dlmzb. r12,r5,r6 |
| add r4,r4,r12 |
| bne L(end_strlen) |
| lwz r5,8(r3) |
| lwz r6,12(r3) |
| dlmzb. r12,r5,r6 |
| add r4,r4,r12 |
| bne L(end_strlen) |
| lwz r5,16(r3) |
| lwz r6,20(r3) |
| dlmzb. r12,r5,r6 |
| add r4,r4,r12 |
| bne L(end_strlen) |
| lwz r5,24(r3) |
| lwz r6,28(r3) |
| addi r3,r3,0x20 |
| dlmzb. r12,r5,r6 |
| add r4,r4,r12 |
| bne L(end_strlen) |
| b L(byte_count_loop) |
| |
| L(end_strlen): |
| addi r3,r4,-1 |
| blr |
| END (strlen) |
| libc_hidden_builtin_def (strlen) |
