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/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from locore.s.
*
* 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 <machine/asm.h>
#if defined(LIBC_SCCS)
RCSID("$NetBSD: bcopy.S,v 1.5 2014/03/22 19:16:34 jakllsch Exp $")
#endif
/*
* (ov)bcopy (src,dst,cnt)
* ws@tools.de (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
*
* Hacked about by dsl@netbsd.org
*/
#ifdef MEMCOPY
ENTRY(memcpy)
#define NO_OVERLAP
#else
#ifdef MEMMOVE
ENTRY(memmove)
#else
ENTRY(bcopy)
#endif
#endif
movq %rdx,%rcx
#if defined(MEMCOPY) || defined(MEMMOVE)
movq %rdi,%rax /* must return destination address */
mov %rdi,%r11 /* for misaligned check */
#else
mov %rsi,%r11 /* for misaligned check */
xchgq %rdi,%rsi /* bcopy() has arg order reversed */
#endif
#if !defined(NO_OVERLAP)
movq %rdi,%r8
subq %rsi,%r8
#endif
shrq $3,%rcx /* count for copy by words */
jz 8f /* j if less than 8 bytes */
lea -8(%rdi,%rdx),%r9 /* target address of last 8 */
mov -8(%rsi,%rdx),%r10 /* get last word */
#if !defined(NO_OVERLAP)
cmpq %rdx,%r8 /* overlapping? */
jb 10f
#endif
/*
* Non-overlaping, copy forwards.
* Newer Intel cpus (Nehalem) will do 16byte read/write transfers
* if %ecx is more than 76.
* AMD might do something similar some day.
*/
and $7,%r11 /* destination misaligned ? */
jnz 2f
rep
movsq
mov %r10,(%r9) /* write last word */
ret
/*
* Destination misaligned
* AMD say it is better to align the destination (not the source).
* This will also re-align copies if the source and dest are both
* misaligned by the same amount)
* (I think Nehalem will use its accelerated copy if the source
* and destination have the same alignment.)
*/
2:
lea -9(%r11,%rdx),%rcx /* post re-alignment count */
neg %r11 /* now -1 .. -7 */
mov (%rsi),%rdx /* get first word */
mov %rdi,%r8 /* target for first word */
lea 8(%rsi,%r11),%rsi
lea 8(%rdi,%r11),%rdi
shr $3,%rcx
rep
movsq
mov %rdx,(%r8) /* write first word */
mov %r10,(%r9) /* write last word */
ret
#if !defined(NO_OVERLAP)
/* Must copy backwards.
* Reverse copy is probably easy to code faster than 'rep movds'
* since that requires (IIRC) an extra clock every 3 iterations (AMD).
* However I don't suppose anything cares that much!
* The big cost is the std/cld pair - reputedly 50+ cycles on Netburst P4.
* The copy is aligned with the buffer start (more likely to
* be a multiple of 8 than the end).
*/
10:
lea -8(%rsi,%rcx,8),%rsi
lea -8(%rdi,%rcx,8),%rdi
std
rep
movsq
cld
mov %r10,(%r9) /* write last bytes */
ret
#endif
/* Less than 8 bytes to copy, copy by bytes */
/* Intel Nehalem optimise 'rep movsb' for <= 7 bytes (9-15 clocks).
* For longer transfers it is 50+ !
*/
8: mov %rdx,%rcx
#if !defined(NO_OVERLAP)
cmpq %rdx,%r8 /* overlapping? */
jb 81f
#endif
/* nope, copy forwards. */
rep
movsb
ret
#if !defined(NO_OVERLAP)
/* Must copy backwards */
81:
lea -1(%rsi,%rcx),%rsi
lea -1(%rdi,%rcx),%rdi
std
rep
movsb
cld
ret
#endif
#ifdef MEMCOPY
END(memcpy)
#else
#ifdef MEMMOVE
END(memmove)
#else
END(bcopy)
#endif
#endif
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