/* Copyright (c) 2009  Dmitry Xmelkov
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   * Neither the name of the copyright holders nor the names of
     contributors may be used to endorse or promote products derived
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   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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   ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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# $Id: readme_eeprom.txt,v 1.1.2.2 2009/06/20 07:23:15 dmix Exp $

Register usage of internally-used functions, common archs:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    eeprom_read_blraw:
	Input:
	    r27,r26	- data space address (destination)
	    r25,r24	- EEPROM address
	    r21,r20	- number of bytes
	Scratch:
	    common call-used regs.

    eeprom_update_r18:
	Input:
	    r18		- byte to write
	    r25,r24	- EEPROM address
	Output:
	    r25,r24	- decremented EEPROM address
	Scratch:
	    r0

    eeprom_update_byte:
	Input:
	    r22		- byte to write
	    r25,r24	- EEPROM address
	Output:
	    r25,r24	- decremented EEPROM address
	Scratch:
	    r18,r0
    
    eeprom_write_r18:
	Input:
	    r18		- byte to write
	    r25,r24	- EEPROM address
	Output:
	    r25,r24	- incremented EEPROM address
	Scratch:
	    r0
    
    eeprom_write_byte:
	Input:
	    r22		- byte to write
	    r25,r24	- EEPROM address
	Output:
	    r25,r24	- incremented EEPROM address
	Scratch:
	    r18,r0


Register usage of internally-used functions, XMEGA arch:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    eeprom_mapen:
	Input:
	    r25,r24	- EEPROM address
	Output:
	    ZH,ZL	- EEPROM address + 0x2000 (to use mapping)
	Scratch:
	    r19

    eeprom_update_r18:
	Input:
	    r18		- byte to write
	    r25,r24	- EEPROM address
	Output:
	    r25,r24	- decremented EEPROM address
	Scratch:
	    r31,r30,r19,r18,r0

    eeprom_update_byte:
	Input:
	    r22		- byte to write
	    r25,r24	- EEPROM address
	Output:
	    r25,r24	- decremented EEPROM address
	Scratch:
	    r31,r30,r19,r18,r0

    eeprom_write_r18:
	Input:
	    r18		- byte to write
	    r25,r24	- EEPROM address
	Output:
	    r25,r24	- incremented EEPROM address
	Scratch:
	    r31,r30,r19,r18

    eeprom_write_byte:
	Input:
	    r22		- byte to write
	    r25,r24	- EEPROM address
	Output:
	    r25,r24	- incremented EEPROM address
	Scratch:
	    r31,r30,r19,r18
