# memmove.S

/* Copyright (c) 2002, 2007 Marek Michalkiewicz

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* 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.
* Neither the name of the copyright holders nor the names of
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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. */

/* $Id$ */

/** \file */
/** \ingroup avr_string
\fn void *memmove(void *dest, const void *src, size_t len)
\brief Copy memory area.

The memmove() function copies len bytes from memory area src to memory area
dest.  The memory areas may overlap.

\returns The memmove() function returns a pointer to dest.  */

#if !defined(__DOXYGEN__)

#include "macros.inc"

#define dest_hi r25
#define dest_lo r24
#define src_hi r23
#define src_lo r22
#define len_hi r21
#define len_lo r20

.extern _U(memcpy)
ASSEMBLY_CLIB_SECTION
.global _U(memmove)
.type   _U(memmove), @function
_U(memmove):
; if src < dest, we have to copy in reverse order
; otherwise memcpy will do the right thing
cp      src_lo, dest_lo
cpc     src_hi, dest_hi
brcc    .L_memmove_fwd
X_movw  ZL, src_lo
X_movw  XL, dest_lo
rjmp    .L_memmove_start
.L_memmove_loop:
ld      __tmp_reg__, -Z
st      -X, __tmp_reg__
.L_memmove_start:
subi    len_lo, lo8(1)
sbci    len_hi, hi8(1)
brcc    .L_memmove_loop
; return dest (unchanged)
ret
.L_memmove_fwd:
XJMP    _U(memcpy)
.L_memmove_end:
.size   _U(memmove), .L_memmove_end - _U(memmove)

#endif /* not __DOXYGEN__ */