xref: /titanic_41/usr/src/lib/libc/sparc/gen/memset.s (revision 9a70fc3be3b1e966bf78825cdb8d509963a6f0a1)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

	.file	"memset.s"

/*
 * char *memset(sp, c, n)
 *
 * Set an array of n chars starting at sp to the character c.
 * Return sp.
 *
 * Fast assembler language version of the following C-program for memset
 * which represents the `standard' for the C-library.
 *
 *	void *
 *	memset(void *sp1, int c, size_t n)
 *	{
 *	    if (n != 0) {
 *		char *sp = sp1;
 *		do {
 *		    *sp++ = (char)c;
 *		} while (--n != 0);
 *	    }
 *	    return (sp1);
 *	}
 */

#include <sys/asm_linkage.h>

	ANSI_PRAGMA_WEAK(memset,function)

	ENTRY(memset)
	mov	%o0, %o5		! copy sp before using it
	cmp	%o2, 7			! if small counts, just write bytes
	blu	.wrchar
	.empty				! following lable is ok in delay slot

.walign:btst	3, %o5			! if bigger, align to 4 bytes
	bz	.wrword
	andn	%o2, 3, %o3		! create word sized count in %o3
	dec	%o2			! decrement count
	stb	%o1, [%o5]		! clear a byte
	b	.walign
	inc	%o5			! next byte

.wrword:and	%o1, 0xff, %o1		! generate a word filled with c
	sll	%o1, 8, %o4
	or 	%o1, %o4, %o1
	sll	%o1, 16, %o4
	or	%o1, %o4, %o1
1:	st	%o1, [%o5]		! word writing loop
	subcc	%o3, 4, %o3
	bnz	1b
	inc	4, %o5

	and	%o2, 3, %o2		! leftover count, if any
.wrchar:deccc	%o2			! byte clearing loop
	inc	%o5
	bgeu,a	.wrchar
	stb	%o1, [%o5 + -1]		! we've already incremented the address

	retl
	nop

	SET_SIZE(memset)