usr/src/lib/libc/i386/gen/memset.s

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27         .file   "memset.s"
  28
  29 #include <sys/asm_linkage.h>
  30
  31         ANSI_PRAGMA_WEAK(memset,function)
  32
  33 #include "SYS.h"
  34
  35         ENTRY(memset)
  36         pushl   %edi            / save register variable
  37         movl    8(%esp),%edi    / %edi = string address
  38         movl    12(%esp),%eax   / %al = byte to duplicate
  39         movl    16(%esp),%ecx   / %ecx = number of copies
  40         cmpl    $20,%ecx        / strings with 20 or more chars should
  41         jbe     .byteset        / byteset one word at a time
  42 .wordset:
  43         andl    $0xff,%eax      / Duplicate fill const 4 times in %eax
  44         shrl    $2,%ecx         / %ecx = number of words to set
  45         movl    %eax,%edx
  46         shll    $8,%eax         / This is ugly, but no P6 partial stalls
  47         orl     %edx,%eax       / get introduced as before
  48         shll    $8,%eax
  49         orl     %edx,%eax
  50         shll    $8,%eax
  51         orl     %edx,%eax
  52         rep; sstol
  53         movl    16(%esp),%ecx
  54         andl    $3,%ecx         / %ecx = number of bytes left
  55 .byteset:
  56         rep; sstob
  57         movl    8(%esp),%eax    / return string address
  58         popl    %edi            / restore register variable
  59         ret
  60         SET_SIZE(memset)