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Arduino/hardware/arduino/avr/libraries/EEPROM/EEPROM.h
Chris--A d6637e7f08 Updated EEPROM storage class
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)
2015-03-18 18:56:08 +10:00

158 lines
5.5 KiB
C++

/*
EEPROM.h - EEPROM library
Original Copyright (c) 2006 David A. Mellis. All right reserved.
New version by Christopher Andrews 2015.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef EEPROM_h
#define EEPROM_h
#include <inttypes.h>
#include <avr/eeprom.h>
#include <avr/io.h>
/***
EERef class.
This object references an EEPROM cell.
Its purpose is to mimic a typical byte of RAM, however its storage is the EEPROM.
This class has an overhead of two bytes, similar to storing a pointer to an EEPROM cell.
***/
struct EERef{
EERef( const int index )
: index( index ) {}
//Access/read members.
uint8_t operator*() const { return eeprom_read_byte( (uint8_t*) index ); }
operator const uint8_t() const { return **this; }
//Assignment/write members.
EERef &operator=( const EERef &ref ) { return *this = *ref; }
EERef &operator=( uint8_t in ) { return eeprom_write_byte( (uint8_t*) index, in ), *this; }
EERef &operator +=( uint8_t in ) { return *this = **this + in; }
EERef &operator -=( uint8_t in ) { return *this = **this - in; }
EERef &operator *=( uint8_t in ) { return *this = **this * in; }
EERef &operator /=( uint8_t in ) { return *this = **this / in; }
EERef &operator ^=( uint8_t in ) { return *this = **this ^ in; }
EERef &operator %=( uint8_t in ) { return *this = **this % in; }
EERef &operator &=( uint8_t in ) { return *this = **this & in; }
EERef &operator |=( uint8_t in ) { return *this = **this | in; }
EERef &operator <<=( uint8_t in ) { return *this = **this << in; }
EERef &operator >>=( uint8_t in ) { return *this = **this >> in; }
EERef &update( uint8_t in ) { return in != *this ? *this = in : *this; }
/** Prefix increment/decrement **/
EERef& operator++() { return *this += 1; }
EERef& operator--() { return *this -= 1; }
/** Postfix increment/decrement **/
uint8_t operator++ (int){
uint8_t ret = **this;
return ++(*this), ret;
}
uint8_t operator-- (int){
uint8_t ret = **this;
return --(*this), ret;
}
int index; //Index of current EEPROM cell.
};
/***
EEPtr class.
This object is a bidirectional pointer to EEPROM cells represented by EERef objects.
Just like a normal pointer type, this can be dereferenced and repositioned using
increment/decrement operators.
***/
struct EEPtr{
EEPtr( const int index )
: index( index ) {}
operator const int() const { return index; }
EEPtr &operator=( int in ) { return index = in, *this; }
//Iterator functionality.
bool operator!=( const EEPtr &ptr ) { return index != ptr.index; }
EERef operator*() { return( this->index ); }
/** Prefix increment/decrement **/
EEPtr& operator++() { return ++index, *this; }
EEPtr& operator--() { return --index, *this; }
/** Postfix increment/decrement **/
EEPtr operator++ (int){
int ret = index;
return ++index, ret;
}
EEPtr operator-- (int){
int ret = index;
return --index, ret;
}
int index; //Index of current EEPROM cell.
};
/***
EEPROMClass class.
This object represents the entire EEPROM space.
It wraps the functionality of EEPtr and EERef into a basic interface.
This class is also 100% backwards compatible with earlier Arduino core releases.
***/
struct EEPROMClass{
//Basic user access methods.
EERef operator[]( const int index ) { return( index ); }
uint8_t read( int idx ) { return (EERef( idx )); }
void write( int idx, uint8_t val ) { (EERef( idx )) = val; }
void update( int idx, uint8_t val ) { EERef( idx ).update( val ); }
//STL and C++11 iteration capability.
EEPtr begin() { return( 0x00 ); }
EEPtr end() { return length(); } //Standards requires this to be the item after the last valid entry. The returned pointer is invalid.
uint16_t length() { return E2END + 1; }
//Functionality to 'get' and 'put' objects to and from EEPROM.
template< typename T > T &get( int idx, T &t ){
EEPtr e = idx;
uint8_t *ptr = (uint8_t*) &t;
for( int count = sizeof(T) ; count ; --count, ++e ) *ptr++ = *e;
return t;
}
template< typename T > const T &put( int idx, const T &t ){
EEPtr e = idx;
const uint8_t *ptr = (const uint8_t*) &t;
for( int count = sizeof(T) ; count ; --count, ++e ) (*e).update( *ptr++ );
return t;
}
};
static EEPROMClass EEPROM;
#endif