minix/lib/nbsd_libc/arch/mips/string/bzero.S
Gianluca Guida b6cbf7203b Import unmodified NetBSD libc in trunk
This patch imports the unmodified current version of NetBSD libc.
The NetBSD includes are in /nbsd_include, while the libc code itself is 
split between lib/nbsd_libc and common/lib/libc.
2011-02-14 19:36:03 +00:00

97 lines
3.4 KiB
ArmAsm

/* $NetBSD: bzero.S,v 1.10 2009/12/14 02:53:52 matt Exp $ */
/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Ralph Campbell.
*
* 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 <mips/asm.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
RCSID("from: @(#)bzero.s 8.1 (Berkeley) 6/4/93")
#else
RCSID("$NetBSD: bzero.S,v 1.10 2009/12/14 02:53:52 matt Exp $")
#endif
#endif /* LIBC_SCCS and not lint */
#define _LOCORE /* XXX not really, just assembly-code source */
#include <machine/endian.h>
/* bzero(s1, n) */
LEAF(bzero)
.set noreorder
blt a1, 3*SZREG, smallclr # small amount to clear?
PTR_SUBU a3, zero, a0 # compute # bytes to word align address
and a3, a3, SZREG-1
beq a3, zero, 1f # skip if word aligned
#if SZREG == 4
PTR_SUBU a1, a1, a3 # subtract from remaining count
SWHI zero, 0(a0) # clear 1, 2, or 3 bytes to align
PTR_ADDU a0, a0, a3
#endif
#if SZREG == 8
PTR_SUBU a1, a1, a3 # subtract from remaining count
PTR_ADDU a0, a0, a3 # align dst to next word
sll a3, a3, 3 # bits to bytes
li a2, -1 # make a mask
#if _BYTE_ORDER == _BIG_ENDIAN
REG_SRLV a2, a2, a3 # we want to keep the MSB bytes
#endif
#if _BYTE_ORDER == _LITTLE_ENDIAN
REG_SLLV a2, a2, a3 # we want to keep the LSB bytes
#endif
nor a2, zero, a2 # complement the mask
REG_L v0, -SZREG(a0) # load the word to partially clear
and v0, v0, a2 # clear the bytes
REG_S v0, -SZREG(a0) # store it back
#endif
1:
and v0, a1, SZREG-1 # compute number of words left
PTR_SUBU a3, a1, v0
move a1, v0
PTR_ADDU a3, a3, a0 # compute ending address
2:
PTR_ADDU a0, a0, SZREG # clear words
bne a0, a3, 2b # unrolling loop doesnt help
REG_S zero, -SZREG(a0) # since we are limited by memory speed
smallclr:
ble a1, zero, 2f
PTR_ADDU a3, a1, a0 # compute ending address
1:
PTR_ADDU a0, a0, 1 # clear bytes
bne a0, a3, 1b
sb zero, -1(a0)
2:
j ra
nop
END(bzero)