aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/i386/memcmp.S
diff options
context:
space:
mode:
authorRoland McGrath <roland@gnu.org>1995-10-16 01:37:51 +0000
committerRoland McGrath <roland@gnu.org>1995-10-16 01:37:51 +0000
commit8f5ca04bc7fd53741d80117df992995ace8f6d2d (patch)
treee39c13fc198b22ec55647259a8080051988e8c69 /sysdeps/i386/memcmp.S
parent5d82cf5c55f56ae10d3b0a205d1fcc7de1cf56a0 (diff)
downloadglibc-8f5ca04bc7fd53741d80117df992995ace8f6d2d.zip
glibc-8f5ca04bc7fd53741d80117df992995ace8f6d2d.tar.gz
glibc-8f5ca04bc7fd53741d80117df992995ace8f6d2d.tar.bz2
Sat Oct 14 02:52:36 1995 Ulrich Drepper <drepper@ipd.info.uni-karlsruhe.de>
* malloc/malloc.c (_malloc_internal): Performance fix. Move if statement out of loop. * stdio/_itoa.c, stdio/_itoa.h: Complete rewrite. Much faster implementation using GMP functions. Contributed by Torbjorn Granlund and Ulrich Drepper. * stdio/test_rdwr.c: Include <errno.h>. * sysdeps/i386/i586/Implies: New file. New highly optimized string functions for i[345]86. * sysdeps/i386/memchr.S, sysdeps/i386/memcmp.S: New files. * sysdeps/i386/stpcpy.S, sysdeps/i386/stpncpy.S: New files. * sysdeps/i386/strchr.S, sysdeps/i386/strcspn.S: New files. * sysdeps/i386/strpbrk.S, sysdeps/i386/strrchr.S: New files. * sysdeps/i386/strspn.S, sysdeps/i386/i486/strcat.S: New files. * sysdeps/i386/i486/strlen.S, sysdeps/i386/i586/strchr.S: New files. * sysdeps/i386/i586/strlen.S: New file. * sysdeps/i386/memchr.c: Removed. There is now an assembler version. * sysdeps/i386/i586/memcopy.h (WORD_COPY_BWD): Parameters did not correspond to used values. * sysdeps/unix/sysv/linux/nfs/nfs.h: New file. Simply a wrapper around a kernel header file. * sysdeps/unix/sysv/linux/Dist: Add it. * sysdeps/unix/sysv/linux/Makefile [$(subdir)=sunrpc] (headers): Likewise. * sysdeps/unix/sysv/linux/local_lim.h: Rewrite. Instead of defining ourself we use a kernel header file. * sysdeps/unix/sysv/linux/i386/sysdep.h (DO_CALL): Optimize system call handler for i586. * sysdeps/unix/sysv/linux/sys/param.h: Add copyright and clean up. Sat Oct 14 02:52:36 1995 Ulrich Drepper <drepper@ipd.info.uni-karlsruhe.de> * malloc/malloc.c (_malloc_internal): Performance fix. Move if statement out of loop. * stdio/_itoa.c, stdio/_itoa.h: Complete rewrite. Much faster implementation using GMP functions. Contributed by Torbjorn Granlund and Ulrich Drepper. * stdio/test_rdwr.c: Include <errno.h>. * sysdeps/i386/i586/Implies: New file. New highly optimized string functions for i[345]86. * sysdeps/i386/memchr.S, sysdeps/i386/memcmp.S: New files. * sysdeps/i386/stpcpy.S, sysdeps/i386/stpncpy.S: New files. * sysdeps/i386/strchr.S, sysdeps/i386/strcspn.S: New files. * sysdeps/i386/strpbrk.S, sysdeps/i386/strrchr.S: New files. * sysdeps/i386/strspn.S, sysdeps/i386/i486/strcat.S: New files. * sysdeps/i386/i486/strlen.S, sysdeps/i386/i586/strchr.S: New files. * sysdeps/i386/i586/strlen.S: New file. * sysdeps/i386/memchr.c: Removed. There is now an assembler version. * sysdeps/i386/i586/memcopy.h (WORD_COPY_BWD): Parameters did not correspond to used values. * sysdeps/unix/sysv/linux/nfs/nfs.h: New file. Simply a wrapper around a kernel header file. * sysdeps/unix/sysv/linux/Dist: Add it. * sysdeps/unix/sysv/linux/Makefile [$(subdir)=sunrpc] (headers): Likewise. * sysdeps/unix/sysv/linux/local_lim.h: Rewrite. Instead of defining ourself we use a kernel header file. * sysdeps/unix/sysv/linux/i386/sysdep.h (DO_CALL): Optimize system call handler for i586. * sysdeps/unix/sysv/linux/sys/param.h: Add copyright and clean up.
Diffstat (limited to 'sysdeps/i386/memcmp.S')
-rw-r--r--sysdeps/i386/memcmp.S68
1 files changed, 68 insertions, 0 deletions
diff --git a/sysdeps/i386/memcmp.S b/sysdeps/i386/memcmp.S
new file mode 100644
index 0000000..f16b44a
--- /dev/null
+++ b/sysdeps/i386/memcmp.S
@@ -0,0 +1,68 @@
+/* memcmp -- compare two memory blocks for differences in the first COUNT
+ bytes.
+Copyright (C) 1995 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 Library General Public License as
+published by the Free Software Foundation; either version 2 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA. */
+
+#include <sysdep.h>
+#include "asm-syntax.h"
+
+/*
+ INPUT PARAMETERS:
+ block1 (sp + 4)
+ block2 (sp + 8)
+ len (sp + 12)
+*/
+
+ .text
+ENTRY (memcmp)
+ pushl %esi /* Save callee-safe registers. */
+ movl %edi, %edx /* Note that %edx is not used and can
+ so be used to save %edi. It's faster. */
+
+ movl 12(%esp), %esi /* Load address of block #1. */
+ movl 16(%esp), %edi /* Load address of block #2. */
+ movl 20(%esp), %ecx /* Load maximal length of compare area. */
+
+ cld /* Set direction of comparison. */
+
+ xorl %eax, %eax /* Default result. */
+
+ repe /* Compare at most %ecx bytes. */
+ cmpsb
+ jz L1 /* If even last byte was equal we return 0. */
+
+ /* The memory blocks are not equal. So result of the last
+ subtraction is present in the carry flag. It is set when
+ the byte in block #2 is bigger. In this case we have to
+ return -1 (=0xffffffff), else 1. */
+ sbbl %eax, %eax /* This is tricky. %eax == 0 and carry is set
+ or not depending on last subtraction. */
+
+ /* At this point %eax == 0, if the byte of block #1 was bigger, and
+ 0xffffffff if the last byte of block #2 was bigger. The later
+ case is already correct but the former needs a little adjustment.
+ Note that the following operation does not change 0xffffffff. */
+ orb $1, %al /* Change 0 to 1. */
+
+L1: popl %esi /* Restore registers. */
+ movl %edx, %edi
+
+ ret
+
+#undef bcmp
+weak_alias (memcmp, bcmp)