flash.h

Go to the documentation of this file.

//   Copyright 2016-2023 Jean-Francois Poilpret
//
//   Licensed under the Apache License, Version 2.0 (the "License");
//   you may not use this file except in compliance with the License.
//   You may obtain a copy of the License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
//   Unless required by applicable law or agreed to in writing, software
//   distributed under the License is distributed on an "AS IS" BASIS,
//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//   See the License for the specific language governing permissions and
//   limitations under the License.
 
 
#ifndef FLASH_HH
#define FLASH_HH
 
#include "boards/io.h"
#include <avr/pgmspace.h>
 
namespace flash
{
    // Utility to handle PROGMEM storage for strings
    class FlashStorage;
 
    template<typename T = uint8_t>
    T* read_flash(uint16_t address, T* buffer, uint8_t size)
    {
        uint8_t* ptr = (uint8_t*) buffer;
        for (size_t i = 0; i < (size * sizeof(T)); ++i) *ptr++ = pgm_read_byte(address++);
        return buffer;
    }
 
    template<typename T> T& read_flash(uint16_t address, T& item)
    {
        uint8_t* ptr = (uint8_t*) &item;
        for (size_t i = 0; i < sizeof(T); ++i) *ptr++ = pgm_read_byte(address++);
        return item;
    }
 
    template<typename T> T& read_flash(const T* address, T& item)
    {
        return read_flash((uint16_t) address, item);
    }
 
    template<typename T> class FlashReader
    {
    public:
        explicit FlashReader(const T* flash_buffer) : address_{uint16_t(flash_buffer)} {}
 
        T operator()()
        {
            T item;
            read_flash(address_, item);
            address_ += sizeof(T);
            return item;
        }
 
    private:
        uint16_t address_;
    };
}
 
#define F(ptr)                                   \
    (__extension__({                             \
        static const char __c[] PROGMEM = (ptr); \
        (const flash::FlashStorage*) &__c[0];    \
    }))
 
#endif /* FLASH_HH */