glibc/sysdeps/aarch64/rawmemchr.S

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/* rawmemchr - find a character in a memory zone
Copyright (C) 2015-2019 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>
/* Special case rawmemchr (s, 0) as strlen, otherwise tailcall memchr.
Call strlen without setting up a full frame - it preserves x14/x15.
*/
ENTRY (__rawmemchr)
cbz w1, L(do_strlen)
mov x2, -1
b __memchr
L(do_strlen):
mov x15, x30
cfi_return_column (x15)
mov x14, x0
bl __strlen
add x0, x14, x0
ret x15
END (__rawmemchr)
weak_alias (__rawmemchr, rawmemchr)
libc_hidden_builtin_def (__rawmemchr)