bzero.s

来自「C++ 编写的EROS RTOS」· S 代码 · 共 59 行

/*
 * Copyright (C) 1998, 1999, Jonathan S. Shapiro.
 *
 * This file is part of the EROS Operating System runtime library.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, 59 Temple Place - Suite 330 Boston, MA 02111-1307, USA.
 */


#include <eros/machine/asm.h>


/*
 * bcopy(caddr_t dst, size_t len);
 * zero len bytes.
 */
ENTRY(bzero)
	pushl	%ebp
	movl	%esp,%ebp
	
	pushl   %edi
	pushl   %ecx
	pushl   %eax
	
	xorl	%eax,%eax
	movl	12(%ebp),%ecx
	movl	8(%ebp),%edi

	cld
	testl	$3,%ecx
	jnz	1f

	/* word move okay */
	shr	$2,%ecx
	rep 
	stosl
	/* jmp	2f */
	
1:	rep 
	stosb
	
2:	popl	%eax
	popl	%ecx
	popl	%edi
	leave
	ret