# eeupd_byte.S

/* Copyright (c) 2009  Dmitry Xmelkov

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(__AVR_TINY__)

#ifndef __DOXYGEN

#include <avr/io.h>

#if     E2END && __AVR_ARCH__ > 1

#include <avr/eeprom.h>
#include "asmdef.h"
#include "eedef.h"

/* void eeprom_update_byte (unsigned char *eepr, unsigned char val)
void eeprom_update_r18 (unsigned char *eepr, r18)
*/

ENTRY   eeprom_update_byte
mov     r18, r22

ENTRY   eeprom_update_r18

#if     __AVR_XMEGA__

XCALL   eeprom_mapen
ld      __tmp_reg__, Z
cp      __tmp_reg__, r18
breq    1f
XCALL   eeprom_write_r18
sbiw    addr_lo, 1              ; restore initial value
ret

#else

rjmp    1b

# ifdef  EEARH
#  if     E2END > 0xFF
#  else
; This is for chips like ATmega48: the EEAR8 bit must be cleaned.
#  endif
# endif

# if     E2END > 0xFF
# else
# endif

cp      __tmp_reg__, r18
breq    2f

# if     defined (EEPM0) && defined (EEPM1)
; Set programming mode: erase and write.
# elif   defined (EEPM0) || defined (EEPM1)
#  error        /* Unknown EECR register.       */
# endif

cli