| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 1 | /* Optimized strlen for Xtensa. |
| 2 | Copyright (C) 2001, 2007 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, write to the Free |
| 17 | Software Foundation, Inc., 51 Franklin Street - Fifth Floor, |
| 18 | Boston, MA 02110-1301, USA. */ |
| 19 | |
| 20 | #include "../../sysdeps/linux/xtensa/sysdep.h" |
| 21 | #include <bits/xtensa-config.h> |
| 22 | |
| 23 | #ifdef __XTENSA_EB__ |
| 24 | #define MASK0 0xff000000 |
| 25 | #define MASK1 0x00ff0000 |
| 26 | #define MASK2 0x0000ff00 |
| 27 | #define MASK3 0x000000ff |
| 28 | #else |
| 29 | #define MASK0 0x000000ff |
| 30 | #define MASK1 0x0000ff00 |
| 31 | #define MASK2 0x00ff0000 |
| 32 | #define MASK3 0xff000000 |
| 33 | #endif |
| 34 | |
| 35 | .text |
| 36 | ENTRY (strlen) |
| 37 | /* a2 = s */ |
| 38 | |
| 39 | addi a3, a2, -4 /* because we overincrement at the end */ |
| 40 | movi a4, MASK0 |
| 41 | movi a5, MASK1 |
| 42 | movi a6, MASK2 |
| 43 | movi a7, MASK3 |
| 44 | bbsi.l a2, 0, .L1mod2 |
| 45 | bbsi.l a2, 1, .L2mod4 |
| 46 | j .Laligned |
| 47 | |
| 48 | .L1mod2: /* address is odd */ |
| 49 | l8ui a8, a3, 4 /* get byte 0 */ |
| 50 | addi a3, a3, 1 /* advance string pointer */ |
| 51 | beqz a8, .Lz3 /* if byte 0 is zero */ |
| 52 | bbci.l a3, 1, .Laligned /* if string pointer is now word-aligned */ |
| 53 | |
| 54 | .L2mod4: /* address is 2 mod 4 */ |
| 55 | addi a3, a3, 2 /* advance ptr for aligned access */ |
| 56 | l32i a8, a3, 0 /* get word with first two bytes of string */ |
| 57 | bnone a8, a6, .Lz2 /* if byte 2 (of word, not string) is zero */ |
| 58 | bany a8, a7, .Laligned /* if byte 3 (of word, not string) is nonzero */ |
| 59 | |
| 60 | /* Byte 3 is zero. */ |
| 61 | addi a3, a3, 3 /* point to zero byte */ |
| 62 | sub a2, a3, a2 /* subtract to get length */ |
| 63 | retw |
| 64 | |
| 65 | |
| 66 | /* String is word-aligned. */ |
| 67 | |
| 68 | .align 4 |
| 69 | /* (2 mod 4) alignment for loop instruction */ |
| 70 | .Laligned: |
| 71 | #if XCHAL_HAVE_LOOPS |
| 72 | _movi.n a8, 0 /* set up for the maximum loop count */ |
| 73 | loop a8, .Lz3 /* loop forever (almost anyway) */ |
| 74 | #endif |
| 75 | 1: l32i a8, a3, 4 /* get next word of string */ |
| 76 | addi a3, a3, 4 /* advance string pointer */ |
| 77 | bnone a8, a4, .Lz0 /* if byte 0 is zero */ |
| 78 | bnone a8, a5, .Lz1 /* if byte 1 is zero */ |
| 79 | bnone a8, a6, .Lz2 /* if byte 2 is zero */ |
| 80 | #if XCHAL_HAVE_LOOPS |
| 81 | bnone a8, a7, .Lz3 /* if byte 3 is zero */ |
| 82 | #else |
| 83 | bany a8, a7, 1b /* repeat if byte 3 is non-zero */ |
| 84 | #endif |
| 85 | |
| 86 | .Lz3: /* Byte 3 is zero. */ |
| 87 | addi a3, a3, 3 /* point to zero byte */ |
| 88 | /* Fall through.... */ |
| 89 | |
| 90 | .Lz0: /* Byte 0 is zero. */ |
| 91 | sub a2, a3, a2 /* subtract to get length */ |
| 92 | retw |
| 93 | |
| 94 | .Lz1: /* Byte 1 is zero. */ |
| 95 | addi a3, a3, 1 /* point to zero byte */ |
| 96 | sub a2, a3, a2 /* subtract to get length */ |
| 97 | retw |
| 98 | |
| 99 | .Lz2: /* Byte 2 is zero. */ |
| 100 | addi a3, a3, 2 /* point to zero byte */ |
| 101 | sub a2, a3, a2 /* subtract to get length */ |
| 102 | retw |
| 103 | |
| 104 | libc_hidden_def (strlen) |