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/* 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)
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