/*      $NetBSD: bzero.S,v 1.6 2013/09/07 19:06:29 chs Exp $    */

/*-
* Copyright (c) 1997 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by J.T. Conklin.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*/

/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* 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. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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>

#if defined(LIBC_SCCS) && !defined(lint)
#if 0
       RCSID("from: @(#)bzero.s        5.1 (Berkeley) 5/12/90")
#else
       RCSID("$NetBSD: bzero.S,v 1.6 2013/09/07 19:06:29 chs Exp $")
#endif
#endif /* LIBC_SCCS and not lint */

ENTRY(bzero)
       movl    %d2,-(%sp)
       movl    8(%sp),%a0              | destination
       movl    12(%sp),%d1             | count

       clrl    %d2

       /*
        * It isn't worth the overhead of aligning to {long}word boundries
        * if the string is too short.
        */
       cmpl    #8,%d1
       jlt     .Lbzbyte

       /* word align */
       movl    %a0,%d0
       btst    #0,%d0                  | if (dst & 1)
       jeq     .Lbzalgndw              |
       movb    %d2,(%a0)+              |       *(char *)dst++ = 0
       subql   #1,%d1                  |       len--
Lbzalgndw:
       /* long word align */
       btst    #1,%d0                  | if (dst & 2)
       jeq     .Lbzalgndl              |
       movw    %d2,(%a0)+              |       *(short *)dst++ = 0
       subql   #2,%d1                  |       len -= 2
Lbzalgndl:
       /* zero by 8 longwords */
       movel   %d1,%d0
       lsrl    #5,%d0                  | cnt = len / 32
       jeq     .Lbzlong                | if (cnt)
       andl    #31,%d1                 |       len %= 32
       subql   #1,%d0                  |       set up for dbf
Lbz32loop:
       movl    %d2,(%a0)+              |       zero 8 long words
       movl    %d2,(%a0)+
       movl    %d2,(%a0)+
       movl    %d2,(%a0)+
       movl    %d2,(%a0)+
       movl    %d2,(%a0)+
       movl    %d2,(%a0)+
       movl    %d2,(%a0)+
#ifndef __mcoldfire__
       dbf     %d0,.Lbz32loop          |       till done
       clrw    %d0
#endif
       subql   #1,%d0
       jcc     .Lbz32loop

Lbzlong:
       /* copy by longwords */
       movel   %d1,%d0
       lsrl    #2,%d0                  | cnt = len / 4
       jeq     .Lbzbyte                | if (cnt)
       subql   #1,%d0                  |       set up for dbf
Lbzlloop:
       movl    %d2,(%a0)+              |       clear longwords
#ifdef __mcoldfire__
       subql   #1,%d0                  |       decrement
       jcc     .Lbzlloop               |       till done
#else
       dbf     %d0,.Lbzlloop           |       till done
#endif
       andl    #3,%d1                  |       len %= 4
       jeq     .Lbzdone

       subql   #1,%d1                  | set up for dbf
Lbzbloop:
       movb    %d2,(%a0)+              | zero bytes
Lbzbyte:
#ifdef __mcoldfire__
       subql   #1,%d0                  | decrement
       jcc     .Lbzbloop               | till done
#else
       dbf     %d1,.Lbzbloop           | till done
#endif
Lbzdone:
       movl    (%sp)+,%d2
       rts
END(bzero)