| /* Optimized strlen for Xtensa. |
| Copyright (C) 2001, 2007 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, write to the Free |
| Software Foundation, Inc., 51 Franklin Street - Fifth Floor, |
| Boston, MA 02110-1301, USA. */ |
| |
| #include "../../sysdeps/linux/xtensa/sysdep.h" |
| #include <bits/xtensa-config.h> |
| |
| #ifdef __XTENSA_EB__ |
| #define MASK0 0xff000000 |
| #define MASK1 0x00ff0000 |
| #define MASK2 0x0000ff00 |
| #define MASK3 0x000000ff |
| #else |
| #define MASK0 0x000000ff |
| #define MASK1 0x0000ff00 |
| #define MASK2 0x00ff0000 |
| #define MASK3 0xff000000 |
| #endif |
| |
| .text |
| ENTRY (strlen) |
| /* a2 = s */ |
| |
| addi a3, a2, -4 /* because we overincrement at the end */ |
| movi a4, MASK0 |
| movi a5, MASK1 |
| movi a6, MASK2 |
| movi a7, MASK3 |
| bbsi.l a2, 0, .L1mod2 |
| bbsi.l a2, 1, .L2mod4 |
| j .Laligned |
| |
| .L1mod2: /* address is odd */ |
| l8ui a8, a3, 4 /* get byte 0 */ |
| addi a3, a3, 1 /* advance string pointer */ |
| beqz a8, .Lz3 /* if byte 0 is zero */ |
| bbci.l a3, 1, .Laligned /* if string pointer is now word-aligned */ |
| |
| .L2mod4: /* address is 2 mod 4 */ |
| addi a3, a3, 2 /* advance ptr for aligned access */ |
| l32i a8, a3, 0 /* get word with first two bytes of string */ |
| bnone a8, a6, .Lz2 /* if byte 2 (of word, not string) is zero */ |
| bany a8, a7, .Laligned /* if byte 3 (of word, not string) is nonzero */ |
| |
| /* Byte 3 is zero. */ |
| addi a3, a3, 3 /* point to zero byte */ |
| sub a2, a3, a2 /* subtract to get length */ |
| retw |
| |
| |
| /* String is word-aligned. */ |
| |
| .align 4 |
| /* (2 mod 4) alignment for loop instruction */ |
| .Laligned: |
| #if XCHAL_HAVE_LOOPS |
| _movi.n a8, 0 /* set up for the maximum loop count */ |
| loop a8, .Lz3 /* loop forever (almost anyway) */ |
| #endif |
| 1: l32i a8, a3, 4 /* get next word of string */ |
| addi a3, a3, 4 /* advance string pointer */ |
| bnone a8, a4, .Lz0 /* if byte 0 is zero */ |
| bnone a8, a5, .Lz1 /* if byte 1 is zero */ |
| bnone a8, a6, .Lz2 /* if byte 2 is zero */ |
| #if XCHAL_HAVE_LOOPS |
| bnone a8, a7, .Lz3 /* if byte 3 is zero */ |
| #else |
| bany a8, a7, 1b /* repeat if byte 3 is non-zero */ |
| #endif |
| |
| .Lz3: /* Byte 3 is zero. */ |
| addi a3, a3, 3 /* point to zero byte */ |
| /* Fall through.... */ |
| |
| .Lz0: /* Byte 0 is zero. */ |
| sub a2, a3, a2 /* subtract to get length */ |
| retw |
| |
| .Lz1: /* Byte 1 is zero. */ |
| addi a3, a3, 1 /* point to zero byte */ |
| sub a2, a3, a2 /* subtract to get length */ |
| retw |
| |
| .Lz2: /* Byte 2 is zero. */ |
| addi a3, a3, 2 /* point to zero byte */ |
| sub a2, a3, a2 /* subtract to get length */ |
| retw |
| |
| libc_hidden_def (strlen) |