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bzero.S revision 1.4 
      1 /*	$NetBSD: bzero.S,v 1.4 2008/04/28 20:22:57 martin Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2006 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Ross Harvey.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,  BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT,  INCIDENTAL,  SPECIAL,  EXEMPLARY,  OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,  PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,  OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY,  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include	<machine/asm.h>
     33 
     34 	.file	"bzero.c"
     35 ENTRY(bzero)
     36 	mr	5, 4		# translate to memcpy signature
     37 	li	4, 0		# add missing memcpy param
     38 ENTRY(memset)
     39 	cmpldi	7, 5, 7		# only optimize if len >= 8
     40 	mr	9, 3
     41 	ble	7, 2f
     42 	rldicl.	0, 3, 0, 61	# only optimize if aligned
     43 	beq	0, 4f
     44 2:
     45 	cmpdi	7, 5, 0
     46 	beqlr	7
     47 3:
     48 	mtctr	5
     49 	rldicl	0, 4, 0, 56
     50 	.p2align 4,, 15
     51 2:
     52 	stb	0, 0(9)		# byte-at-a-time loop
     53 	addi	9, 9, 1
     54 	bdnz	2b
     55 	blr			# done
     56 4:
     57 	rldicl	4, 4, 0, 56	# construct parallel store
     58 	cmpldi	7, 5, 31
     59 	mr	10, 3
     60 	sldi	0, 4, 8
     61 	or	0, 0, 4
     62 	sldi	9, 0, 16
     63 	or	0, 0, 9
     64 	sldi	11, 0, 32
     65 	or	0, 0, 11
     66 	ble	7, 5f
     67 	addi	9, 5, -32
     68 	srdi	9, 9, 5
     69 	addi	9, 9, 1
     70 	mtctr	9
     71 	.p2align 4,, 15
     72 2:
     73 	std	0, 0(10)	# 8-way + unrolled store loop
     74 	std	0, 8(10)
     75 	addi	5, 5, -32	# schedule count decrement
     76 	std	0, 16(10)
     77 	std	0, 24(10)
     78 	addi	10, 10, 32
     79 	bdnz	2b
     80 	cmpldi	7, 5, 7
     81 	ble	7, 8f
     82 5:
     83 	addi	9, 5, -8
     84 	srdi	9, 9, 3
     85 	addi	9, 9, 1
     86 	mtctr	9
     87 	.p2align 4,, 15
     88 14:
     89 	std	0, 0(10)	# 8-way not-unrolled loop
     90 	addi	5, 5, -8
     91 	addi	10, 10, 8
     92 	bdnz	14b
     93 8:
     94 	cmpdi	7, 5, 0
     95 	mr	9, 10
     96 	bne	7, 3b
     97 	blr
     98 	.long	0
     99 	.byte	0, 0, 0, 0, 0, 0, 0, 0
    100 	.size	.memset, .-.memset
    101