//----------------------------------------------------------------------------

//Eeprom support module

//----------------------------------------------------------------------------

#include <Main.h>
#include <Eeprom.h>

//------------------------------ Constants: ----------------------------------

#define RBUFF  100 //EEPROM ring buffer size
#define RSIG  0xDA //record header signature value

//------------------------------ Variables: ----------------------------------

typedef struct
{
  char Sig;     //record header signature
  int  Val;     //stored value
} EVal;

__no_init __eeprom EVal EVals[RBUFF]; //EEPROM ring buffer

static char EePnt = 0;  //pointer to currently used record

//-------------------------- Read V from EEPROM: -----------------------------

int Eeprom_ReadV(void)
{
  EePnt = RBUFF;                  //set incorrect pointer value
  for(char i = 0; i < RBUFF; i++) //search signature in ring buffer
    if(EVals[i].Sig == RSIG)      //if signature found
    {
      EePnt = i;                  //initialize pointer
      break;
    }
  if(EePnt == RBUFF)              //if pointer incorrect (signature not found)
  {
    EePnt = 0;                    //set pointer to first array record
    return(0);                    //return V = 0
  }
  return(EVals[EePnt].Val);       //read V
}

//--------------------------- Write V to EEPROM: -----------------------------

void Eeprom_WriteV(int v)
{
  char NewPnt = EePnt;            //save previous pointer value
  if(NewPnt++ == RBUFF)           //advance pointer
    NewPnt = 0;                   //roll-up pointer
  EVals[NewPnt].Val = v;          //save V
  EVals[NewPnt].Sig = RSIG;       //save signature at new location
  EVals[EePnt].Sig = 0xFF;        //clear signature at old location
  EePnt = NewPnt;                 //save new pointer value
}

//----------------------------------------------------------------------------