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/* $NetBSD: memcpy.S,v 1.1 2014/08/10 05:47:35 matt Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matt Thomas of 3am Software Foundry.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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 <machine/asm.h>
RCSID("$NetBSD: memcpy.S,v 1.1 2014/08/10 05:47:35 matt Exp $")
/* LINTSTUB: void *memcpy(void * restrict, const void * restrict, size_t); */
ENTRY(memcpy)
mov x10, x0
mov x11, x1
cbz x2, .Lmemcpy_ret
cmp x2, #7
b.ls .Lmemcpy_last_dword
ands x3, x10, #7
b.eq .Lmemcpy_dword_aligned
/*
* The dst address doesn't have dword alignment. The src address may or may
* not have the same alignment. Make dst dword aligned. Hope src will be
* dword aligned but if it isn't, take advantage of unaligned access.
*/
add x2, x2, x3 /* add unalignment to length */
sub x2, x2, #8 /* now subtract a dword */
tbz x10, #0, .Lmemcpy_hword_aligned
ldrb w4, [x11], #1
strb w4, [x10], #1
.Lmemcpy_hword_aligned:
tbz x10, #1, .Lmemcpy_word_aligned
ldrh w4, [x11], #2
strh w4, [x10], #2
.Lmemcpy_word_aligned:
tbz x10, #2, .Lmemcpy_dword_aligned
ldr w4, [x11], #4
str w4, [x10], #4
.Lmemcpy_dword_aligned:
/*
* destination is now dword aligned.
*/
subs x2, x2, #32
b.mi .Lmemcpy_last_oword
.Lmemcpy_oword_loop:
ldp x4, x5, [x11], #16
ldp x6, x7, [x11], #16
stp x4, x5, [x10], #16
stp x6, x7, [x10], #16
cbz x2, .Lmemcpy_ret
subs x2, x2, #32
b.pl .Lmemcpy_oword_loop
.Lmemcpy_last_oword:
/*
* We have 31 bytes or less to copy. First see if we can write a qword
*/
tbz x2, #4, .Lmemcpy_last_qword
ldp x4, x5, [x11], #16 /* read word */
stp x4, x5, [x10], #16 /* write word */
.Lmemcpy_last_qword:
/*
* We have 15 bytes or less to copy. First see if we can write a dword
*/
tbz x2, #3, .Lmemcpy_last_dword
ldr x4, [x11], #8 /* read word */
str x4, [x10], #8 /* write word */
.Lmemcpy_last_dword:
/*
* We have 7 bytes or less to copy. First see if we can write a word
*/
tbz x2, #2, .Lmemcpy_last_word
ldr w4, [x11], #4 /* read word */
str w4, [x10], #4 /* write word */
.Lmemcpy_last_word:
/*
* We have 3 bytes or less to copy. First see if we can write a hword
*/
tbz x2, #1, .Lmemcpy_last_hword
ldrh w4, [x11], #2
strh w4, [x10], #2
.Lmemcpy_last_hword:
/*
* We have 1 or none bytes to copy.
*/
tbz x2, #0, .Lmemcpy_ret
ldrb w4, [x11]
strb w4, [x10]
.Lmemcpy_ret:
ret
END(memcpy)
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