mips/string/bzero.S

1.1  glass /*-
1.1  glass  * Copyright (c) 1991, 1993
1.1  glass  *	The Regents of the University of California.  All rights reserved.
1.1  glass  *
1.1  glass  * This code is derived from software contributed to Berkeley by
1.1  glass  * Ralph Campbell.
1.1  glass  *
1.1  glass  * Redistribution and use in source and binary forms, with or without
1.1  glass  * modification, are permitted provided that the following conditions
1.1  glass  * are met:
1.1  glass  * 1. Redistributions of source code must retain the above copyright
1.1  glass  *    notice, this list of conditions and the following disclaimer.
1.1  glass  * 2. Redistributions in binary form must reproduce the above copyright
1.1  glass  *    notice, this list of conditions and the following disclaimer in the
1.1  glass  *    documentation and/or other materials provided with the distribution.
1.1  glass  * 3. All advertising materials mentioning features or use of this software
1.1  glass  *    must display the following acknowledgement:
1.1  glass  *	This product includes software developed by the University of
1.1  glass  *	California, Berkeley and its contributors.
1.1  glass  * 4. Neither the name of the University nor the names of its contributors
1.1  glass  *    may be used to endorse or promote products derived from this software
1.1  glass  *    without specific prior written permission.
1.1  glass  *
1.1  glass  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
1.1  glass  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.1  glass  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.1  glass  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
1.1  glass  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
1.1  glass  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
1.1  glass  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
1.1  glass  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
1.1  glass  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
1.1  glass  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
1.1  glass  * SUCH DAMAGE.
1.1  glass  */
1.1  glass
1.1  glass #include <machine/machAsmDefs.h>
1.1  glass
1.1  glass #if defined(LIBC_SCCS) && !defined(lint)
1.1  glass 	ASMSTR("from: @(#)bzero.s	8.1 (Berkeley) 6/4/93")
1.1  glass 	ASMSTR("$Id: bzero.S,v 1.1 1994/05/24 07:12:50 glass Exp $")
1.1  glass #endif /* LIBC_SCCS and not lint */
1.1  glass
1.1  glass /* bzero(s1, n) */
1.1  glass
1.1  glass LEAF(bzero)
1.1  glass 	.set	noreorder
1.1  glass 	blt	a1, 12, smallclr	# small amount to clear?
1.1  glass 	subu	a3, zero, a0		# compute # bytes to word align address
1.1  glass 	and	a3, a3, 3
1.1  glass 	beq	a3, zero, 1f		# skip if word aligned
1.1  glass 	subu	a1, a1, a3		# subtract from remaining count
1.1  glass 	swr	zero, 0(a0)		# clear 1, 2, or 3 bytes to align
1.1  glass 	addu	a0, a0, a3
1.1  glass 1:
1.1  glass 	and	v0, a1, 3		# compute number of words left
1.1  glass 	subu	a3, a1, v0
1.1  glass 	move	a1, v0
1.1  glass 	addu	a3, a3, a0		# compute ending address
1.1  glass 2:
1.1  glass 	addu	a0, a0, 4		# clear words
1.1  glass 	bne	a0, a3, 2b		#   unrolling loop doesnt help
1.1  glass 	sw	zero, -4(a0)		#   since we are limited by memory speed
1.1  glass smallclr:
1.1  glass 	ble	a1, zero, 2f
1.1  glass 	addu	a3, a1, a0		# compute ending address
1.1  glass 1:
1.1  glass 	addu	a0, a0, 1		# clear bytes
1.1  glass 	bne	a0, a3, 1b
1.1  glass 	sb	zero, -1(a0)
1.1  glass 2:
1.1  glass 	j	ra
1.1  glass 	nop
1.1  glass END(bzero)