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| author | Ulrich Drepper <drepper@redhat.com> | 2010-07-26 08:37:08 -0700 |
|---|---|---|
| committer | Ulrich Drepper <drepper@redhat.com> | 2010-07-26 08:37:08 -0700 |
| commit | 24fb0f88ed29d21b6034559e9c55545f22556bc0 (patch) | |
| tree | 51b61ee2442da648a3fc724437188b2a99aadcff /sysdeps/x86_64/strnlen.S | |
| parent | 8e96b93aa7855683d0be3c65ce81e66d0786ba84 (diff) | |
| download | glibc-24fb0f88ed29d21b6034559e9c55545f22556bc0.tar.gz glibc-24fb0f88ed29d21b6034559e9c55545f22556bc0.tar.xz glibc-24fb0f88ed29d21b6034559e9c55545f22556bc0.zip | |
Add optimized x86-64 implementation of strnlen.
While at it, beef up the test suite for strnlen and add performance tests for it, too.
Diffstat (limited to 'sysdeps/x86_64/strnlen.S')
| -rw-r--r-- | sysdeps/x86_64/strnlen.S | 64 |
1 files changed, 64 insertions, 0 deletions
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) |