From 24fb0f88ed29d21b6034559e9c55545f22556bc0 Mon Sep 17 00:00:00 2001
From: Ulrich Drepper <drepper@redhat.com>
Date: Mon, 26 Jul 2010 08:37:08 -0700
Subject: Add optimized x86-64 implementation of strnlen.

While at it, beef up the test suite for strnlen and add performance
tests for it, too.
---
 sysdeps/x86_64/strnlen.S | 64 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 sysdeps/x86_64/strnlen.S

(limited to 'sysdeps/x86_64')

diff --git a/sysdeps/x86_64/strnlen.S b/sysdeps/x86_64/strnlen.S
new file mode 100644
index 0000000000..939782d3f8
--- /dev/null
+++ b/sysdeps/x86_64/strnlen.S
@@ -0,0 +1,64 @@
+/* strnlen(str,maxlen) -- determine the length of the string STR up to MAXLEN.
+   Copyright (C) 2010 Free Software Foundation, Inc.
+   Contributed by Ulrich Drepper <drepper@redhat.com>.
+   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., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <sysdep.h>
+
+
+	.text
+ENTRY(__strnlen)
+	movq	%rsi, %rax
+	testq	%rsi, %rsi
+	jz	3f
+	pxor	%xmm2, %xmm2
+	movq	%rdi, %rcx
+	movq	%rdi, %r8
+	movq	$16, %r9
+	andq	$~15, %rdi
+	movdqa	%xmm2, %xmm1
+	pcmpeqb	(%rdi), %xmm2
+	orl	$0xffffffff, %r10d
+	subq	%rdi, %rcx
+	shll	%cl, %r10d
+	subq	%rcx, %r9
+	pmovmskb %xmm2, %edx
+	andl	%r10d, %edx
+	jnz	1f
+	subq	%r9, %rsi
+	jbe	3f
+
+2:	movdqa	16(%rdi), %xmm0
+	leaq	16(%rdi), %rdi
+	pcmpeqb	%xmm1, %xmm0
+	pmovmskb %xmm0, %edx
+	testl	%edx, %edx
+	jnz	1f
+	subq	$16, %rsi
+	jnbe	2b
+3:	ret
+
+1:	subq	%r8, %rdi
+	bsfl	%edx, %edx
+	addq	%rdi, %rdx
+	cmpq	%rdx, %rax
+	cmovnbq	%rdx, %rax
+	ret
+END(__strnlen)
+weak_alias (__strnlen, strnlen)
+libc_hidden_def (strnlen)
-- 
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