FM25256
256K bit Ferroelectric Nonvolatile RAM
• Organized as 32,768 x 8 bits
• Virtually Unlimited Endurance (10^14 Cycles)
• 10 Year Data Retention
•Very Fast Serial Peripheral Interface - SPI
• Up to 15 MHz Frequency

#define STORAGE_SIZE 128

typedef struct tagSTORAGE_REC
{
    U8 Sequence;
} TSTORAGE_REC, *PSTORAGE_REC;

TSTORAGE_REC Storage[STORAGE_SIZE];

U8 MaxSequenceIndex(void)
{
    U8 retval = 0;
    U8 max = Storage[0].Sequence;
    U8 i;
    
    for (i = 1; i < COUNT(Storage); i++)
       if (max < Storage[i].Sequence)
       {
          max = Storage[i].Sequence;
          retval = i;
       }
    return retval;
}

#define Next( Index ) ((Index) >= (STORAGE_SIZE -1)) ? 0 : Index + 1;
      
void Store(void)
{
    U8 Idx = MaxSequenceIndex(); // index for the next cell to write data to
    U8 Sq = Storage[ Idx ].Sequence;
    
    if ( Sq == 0xFF )
    { // warp
       U8 OldSq;
       U8 delta;
       do
       {
           OldSq = Sq;
           Idx = Next( Idx );
           Sq = Storage[ Idx ].Sequence;
           delta = Sq - OldSq;
       } while (  delta == 1);
       Sq = OldSq;
    }
    else
    { // normal case
       Idx = Next( Idx );
    }
    Sq += 1;
    Storage[ Idx ].Sequence = Sq; // Записываем..
}