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/* memcpy - copy a block from source to destination. S/390 version.
Copyright (C) 2000, 2001 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/* INPUT PARAMETERS
%r2 = address of destination memory area
%r3 = address of source memory area
%r4 = number of bytes to copy. */
#include "sysdep.h"
#include "asm-syntax.h"
.text
ENTRY(memcpy)
ltr %r4,%r4
jz .L3
ahi %r4,-1 # length - 1
lr %r1,%r2 # copy destination address
lr %r5,%r4
srl %r5,8
ltr %r5,%r5 # < 256 bytes to move ?
jz .L1
chi %r5,255 # > 1MB to move ?
jh .L4
.L0: mvc 0(256,%r1),0(%r3) # move in 256 byte chunks
la %r1,256(%r1)
la %r3,256(%r3)
brct %r5,.L0
.L1: bras %r5,.L2 # setup base pointer for execute
mvc 0(1,%r1),0(%r3) # instruction for execute
.L2: ex %r4,0(%r5) # execute mvc with length ((%r4)&255)+1
.L3: br %r14
# data copies > 1MB are faster with mvcle.
.L4: ahi %r4,1 # length + 1
lr %r5,%r4 # source length
lr %r4,%r2 # source address
lr %r2,%r3 # set destination
lr %r3,%r5 # destination length = source length
.L5: mvcle %r2,%r4,0 # thats it, MVCLE is your friend
jo .L5
lr %r2,%r1 # return destination address
br %r14
END(memcpy)
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