diff options
Diffstat (limited to 'lib/libc/i386/string/memcmp.S')
| -rw-r--r-- | lib/libc/i386/string/memcmp.S | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/lib/libc/i386/string/memcmp.S b/lib/libc/i386/string/memcmp.S new file mode 100644 index 0000000..8aa2f4e --- /dev/null +++ b/lib/libc/i386/string/memcmp.S @@ -0,0 +1,75 @@ +/* + * Copyright (c) 1993 Winning Strategies, Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by Winning Strategies, Inc. + * 4. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include <machine/asm.h> +__FBSDID("$FreeBSD$"); + +/* + * memcmp (void *b1, void *b2, size_t len) + * + * Written by: + * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. + */ + +ENTRY(memcmp) + pushl %edi + pushl %esi + movl 12(%esp),%edi + movl 16(%esp),%esi + cld /* set compare direction forward */ + + movl 20(%esp),%ecx /* compare by words */ + shrl $2,%ecx + repe + cmpsl + jne L5 /* do we match so far? */ + + movl 20(%esp),%ecx /* compare remainder by bytes */ + andl $3,%ecx + repe + cmpsb + jne L6 /* do we match? */ + + xorl %eax,%eax /* we match, return zero */ + popl %esi + popl %edi + ret + +L5: movl $4,%ecx /* We know that one of the next */ + subl %ecx,%edi /* four pairs of bytes do not */ + subl %ecx,%esi /* match. */ + repe + cmpsb +L6: movzbl -1(%edi),%eax /* Perform unsigned comparison */ + movzbl -1(%esi),%edx + subl %edx,%eax + popl %esi + popl %edi + ret |
