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/* Copyright (c) 2009 Dmitry Xmelkov
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: eerd_byte.S,v 1.1.2.2 2009/06/20 07:21:19 dmix Exp $ */
#ifndef __DOXYGEN__
#include <avr/io.h>
#if E2END && __AVR_ARCH__ > 1
#include <avr/eeprom.h>
#include "asmdef.h"
#include "eedef.h"
/* uint8_t eeprom_read_byte (uint8_t EEMEM *addr);
*/
#define ret_lo r24
#define ret_hi r25
ENTRY eeprom_read_byte
#if __AVR_XMEGA__ /* -------------------------------------------- */
rcall eeprom_mapen
ld ret_lo, Z
clr ret_hi
ret
ENTRY eeprom_mapen
; Load base address of NVM.
ldi ZL, lo8(NVM_BASE)
ldi ZH, hi8(NVM_BASE)
; Wait until NVM is not busy.
1: ldd r19, Z + NVM_STATUS - NVM_BASE
sbrc r19, NVM_NVMBUSY_bp
rjmp 1b
; Enable EEPROM mapping into data space.
ldd r19, Z + NVM_CTRLB - NVM_BASE
ori r19, NVM_EEMAPEN_bm
std Z + NVM_CTRLB - NVM_BASE, r19
; Load Z with correct EEPROM address to read from data space.
movw ZL, addr_lo
subi ZL, lo8(-MAPPED_EEPROM_START)
sbci ZH, hi8(-MAPPED_EEPROM_START)
ret
#else /* -------------------------------------------- */
1: sbic _SFR_IO_ADDR (EECR), EEWE
rjmp 1b
# ifdef EEARH
# if E2END > 0xFF
out _SFR_IO_ADDR (EEARH), addr_hi
# else
; This is for chips like ATmega48: the EEAR8 bit must be cleaned.
out _SFR_IO_ADDR (EEARH), __zero_reg__
# endif
# endif
out _SFR_IO_ADDR (EEARL), addr_lo
sbi _SFR_IO_ADDR (EECR), EERE
clr ret_hi
in ret_lo, _SFR_IO_ADDR (EEDR)
ret
#endif /* -------------------------------------------- */
ENDFUNC
#endif /* E2END && __AVR_ARCH__ > 1 */
#endif /* !__DOXYGEN__ */
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