4.142.1 memmove.S

/* Copyright (c) 2002, 2007 Marek Michalkiewicz
   All rights reserved.

   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. */

/* $Id$ */

#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
    add ZL, len_lo
    adc ZH, len_hi
    add XL, len_lo
    adc XH, len_hi
    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__ */