From 8f5ca04bc7fd53741d80117df992995ace8f6d2d Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Mon, 16 Oct 1995 01:37:51 +0000 Subject: Sat Oct 14 02:52:36 1995 Ulrich Drepper * 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 . * 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 [$(subdir)=sunrpc] (headers): Likewise. * sysdeps/unix/sysv/linux/local_lim.h: Rewrite. Instead of defining ourself we use a kernel header file. * sysdeps/unix/sysv/linux/i386/sysdep.h (DO_CALL): Optimize system call handler for i586. * sysdeps/unix/sysv/linux/sys/param.h: Add copyright and clean up. Sat Oct 14 02:52:36 1995 Ulrich Drepper * malloc/malloc.c (_malloc_internal): Performance fix. Move if statement out of loop. * stdio/_itoa.c, stdio/_itoa.h: Complete rewrite. Much faster implementation using GMP functions. Contributed by Torbjorn Granlund and Ulrich Drepper. * stdio/test_rdwr.c: Include . * sysdeps/i386/i586/Implies: New file. New highly optimized string functions for i[345]86. * sysdeps/i386/memchr.S, sysdeps/i386/memcmp.S: New files. * sysdeps/i386/stpcpy.S, sysdeps/i386/stpncpy.S: New files. * sysdeps/i386/strchr.S, sysdeps/i386/strcspn.S: New files. * sysdeps/i386/strpbrk.S, sysdeps/i386/strrchr.S: New files. * sysdeps/i386/strspn.S, sysdeps/i386/i486/strcat.S: New files. * sysdeps/i386/i486/strlen.S, sysdeps/i386/i586/strchr.S: New files. * sysdeps/i386/i586/strlen.S: New file. * sysdeps/i386/memchr.c: Removed. There is now an assembler version. * sysdeps/i386/i586/memcopy.h (WORD_COPY_BWD): Parameters did not correspond to used values. * sysdeps/unix/sysv/linux/nfs/nfs.h: New file. Simply a wrapper around a kernel header file. * sysdeps/unix/sysv/linux/Dist: Add it. * sysdeps/unix/sysv/linux/Makefile [$(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. --- sysdeps/i386/memcmp.S | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 sysdeps/i386/memcmp.S (limited to 'sysdeps/i386/memcmp.S') 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 +#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) -- cgit v1.1