| 1 | /* Optimized strlen implementation for PowerPC476. |
|---|
| 2 | Copyright (C) 2010-2024 Free Software Foundation, Inc. |
|---|
| 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 |
|---|
| 16 | License along with the GNU C Library. If not, see |
|---|
| 17 | <https://www.gnu.org/licenses/>. */ |
|---|
| 18 | |
|---|
| 19 | #include <sysdep.h> |
|---|
| 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 | |
|---|
| 32 | EALIGN (strlen,5,0) |
|---|
| 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 |
|---|
| 74 | END (strlen) |
|---|
| 75 | libc_hidden_builtin_def (strlen) |
|---|
| 76 | |
|---|
