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To avoid having a .cpp just for an extern variable definition, `static` has been chosen over `extern`. As the `EEPROMClass` class simply wraps functionality located elsewhere, it is completely compiled away. Even though each translation unit which includes the header will get a copy with internal linkage, there is no associated overhead. More info [here](http://stackoverflow.com/questions/29098518/extern-variable-only-in-header-unexpectedly-working-why)
158 lines
5.5 KiB
C++
158 lines
5.5 KiB
C++
/*
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EEPROM.h - EEPROM library
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Original Copyright (c) 2006 David A. Mellis. All right reserved.
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New version by Christopher Andrews 2015.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef EEPROM_h
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#define EEPROM_h
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#include <inttypes.h>
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#include <avr/eeprom.h>
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#include <avr/io.h>
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/***
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EERef class.
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This object references an EEPROM cell.
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Its purpose is to mimic a typical byte of RAM, however its storage is the EEPROM.
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This class has an overhead of two bytes, similar to storing a pointer to an EEPROM cell.
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***/
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struct EERef{
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EERef( const int index )
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: index( index ) {}
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//Access/read members.
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uint8_t operator*() const { return eeprom_read_byte( (uint8_t*) index ); }
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operator const uint8_t() const { return **this; }
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//Assignment/write members.
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EERef &operator=( const EERef &ref ) { return *this = *ref; }
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EERef &operator=( uint8_t in ) { return eeprom_write_byte( (uint8_t*) index, in ), *this; }
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EERef &operator +=( uint8_t in ) { return *this = **this + in; }
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EERef &operator -=( uint8_t in ) { return *this = **this - in; }
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EERef &operator *=( uint8_t in ) { return *this = **this * in; }
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EERef &operator /=( uint8_t in ) { return *this = **this / in; }
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EERef &operator ^=( uint8_t in ) { return *this = **this ^ in; }
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EERef &operator %=( uint8_t in ) { return *this = **this % in; }
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EERef &operator &=( uint8_t in ) { return *this = **this & in; }
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EERef &operator |=( uint8_t in ) { return *this = **this | in; }
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EERef &operator <<=( uint8_t in ) { return *this = **this << in; }
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EERef &operator >>=( uint8_t in ) { return *this = **this >> in; }
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EERef &update( uint8_t in ) { return in != *this ? *this = in : *this; }
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/** Prefix increment/decrement **/
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EERef& operator++() { return *this += 1; }
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EERef& operator--() { return *this -= 1; }
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/** Postfix increment/decrement **/
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uint8_t operator++ (int){
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uint8_t ret = **this;
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return ++(*this), ret;
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}
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uint8_t operator-- (int){
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uint8_t ret = **this;
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return --(*this), ret;
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}
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int index; //Index of current EEPROM cell.
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};
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/***
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EEPtr class.
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This object is a bidirectional pointer to EEPROM cells represented by EERef objects.
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Just like a normal pointer type, this can be dereferenced and repositioned using
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increment/decrement operators.
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***/
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struct EEPtr{
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EEPtr( const int index )
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: index( index ) {}
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operator const int() const { return index; }
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EEPtr &operator=( int in ) { return index = in, *this; }
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//Iterator functionality.
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bool operator!=( const EEPtr &ptr ) { return index != ptr.index; }
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EERef operator*() { return( this->index ); }
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/** Prefix increment/decrement **/
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EEPtr& operator++() { return ++index, *this; }
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EEPtr& operator--() { return --index, *this; }
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/** Postfix increment/decrement **/
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EEPtr operator++ (int){
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int ret = index;
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return ++index, ret;
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}
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EEPtr operator-- (int){
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int ret = index;
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return --index, ret;
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}
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int index; //Index of current EEPROM cell.
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};
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/***
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EEPROMClass class.
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This object represents the entire EEPROM space.
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It wraps the functionality of EEPtr and EERef into a basic interface.
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This class is also 100% backwards compatible with earlier Arduino core releases.
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***/
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struct EEPROMClass{
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//Basic user access methods.
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EERef operator[]( const int index ) { return( index ); }
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uint8_t read( int idx ) { return (EERef( idx )); }
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void write( int idx, uint8_t val ) { (EERef( idx )) = val; }
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void update( int idx, uint8_t val ) { EERef( idx ).update( val ); }
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//STL and C++11 iteration capability.
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EEPtr begin() { return( 0x00 ); }
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EEPtr end() { return length(); } //Standards requires this to be the item after the last valid entry. The returned pointer is invalid.
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uint16_t length() { return E2END + 1; }
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//Functionality to 'get' and 'put' objects to and from EEPROM.
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template< typename T > T &get( int idx, T &t ){
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EEPtr e = idx;
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uint8_t *ptr = (uint8_t*) &t;
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for( int count = sizeof(T) ; count ; --count, ++e ) *ptr++ = *e;
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return t;
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}
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template< typename T > const T &put( int idx, const T &t ){
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EEPtr e = idx;
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const uint8_t *ptr = (const uint8_t*) &t;
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for( int count = sizeof(T) ; count ; --count, ++e ) (*e).update( *ptr++ );
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return t;
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}
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};
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static EEPROMClass EEPROM;
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#endif |