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bcopy.S revision 1.2 
      1 /*-
      2  * Copyright (c) 1990 The Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * This code is derived from locore.s.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  *
     35  *	$Id: bcopy.S,v 1.2 1993/10/21 01:40:28 jtc Exp $
     36  */
     37 
     38 #if defined(LIBC_SCCS)
     39 	.text
     40 	.asciz "$Id: bcopy.S,v 1.2 1993/10/21 01:40:28 jtc Exp $"
     41 #endif
     42 
     43 #include "DEFS.h"
     44 
     45 	/*
     46 	 * (ov)bcopy (src,dst,cnt)
     47 	 *  ws (at) tools.de     (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
     48 	 */
     49 
     50 ENTRY(bcopy)
     51 	pushl	%esi
     52 	pushl	%edi
     53 	movl	12(%esp),%esi
     54 	movl	16(%esp),%edi
     55 	movl	20(%esp),%ecx
     56 	cmpl	%esi,%edi	/* potentially overlapping? */
     57 	jnb	1f
     58 	cld			/* nope, copy forwards. */
     59 	shrl	$2,%ecx		/* copy by words */
     60 	rep
     61 	movsl
     62 	movl	20(%esp),%ecx
     63 	andl	$3,%ecx		/* any bytes left? */
     64 	rep
     65 	movsb
     66 	popl	%edi
     67 	popl	%esi
     68 	ret
     69 1:
     70 	addl	%ecx,%edi	/* copy backwards. */
     71 	addl	%ecx,%esi
     72 	std
     73 	andl	$3,%ecx		/* any fractional bytes? */
     74 	decl	%edi
     75 	decl	%esi
     76 	rep
     77 	movsb
     78 	movl	20(%esp),%ecx	/* copy remainder by words */
     79 	shrl	$2,%ecx
     80 	subl	$3,%esi
     81 	subl	$3,%edi
     82 	rep
     83 	movsl
     84 	popl	%edi
     85 	popl	%esi
     86 	cld
     87 	ret
     88