[S] Ringspeicher [msp430]

#include <stdio.h>

#define RINGBUFFER_SIZE  9

#define INVALID_VALUE    -1000

#define LAST_MEAN_VALUES 3

int RingBuffer[ RINGBUFFER_SIZE ];

int RingBufferCurrent;               // zeigt an, wo der nächste Wert abgelegt wird

void InitRingBuffer( void )

{

  unsigned char i;

  RingBufferCurrent = 0;

  for( i = 0; i < RINGBUFFER_SIZE; ++i )

    RingBuffer[i] = INVALID_VALUE;

}

void AddValue( int Value )

{

  RingBuffer[RingBufferCurrent++] = Value;

  if( RingBufferCurrent == RINGBUFFER_SIZE )

    RingBufferCurrent = 0;

}

int MeanValue( void )

{

  unsigned char i;

  unsigned char nrValues = 0;

  long Summ = 0;

  for( i = 0; i < RINGBUFFER_SIZE; ++i ) {

    if( RingBuffer[i] != INVALID_VALUE ) {

      Summ += RingBuffer[i];

      nrValues++;

    }

  }

  if( nrValues == 0 )

    return INVALID_VALUE;

  return Summ / nrValues;

}

int MeanValueOfLast( void )

{

  long Summ = 0;

  unsigned char i = RingBufferCurrent;

  unsigned char nrValues = 0;

  do {

    if( i == 0 )

      i = RINGBUFFER_SIZE - 1;

    else

      --i;

    if( RingBuffer[i] != INVALID_VALUE ) {

      Summ += RingBuffer[i];

      nrValues++;

    }

  } while( nrValues != LAST_MEAN_VALUES && i != RingBufferCurrent );

  if( i == RingBufferCurrent )

    return INVALID_VALUE;

  return Summ / nrValues;

}

void PrintValues( void )

{

  unsigned char i = RingBufferCurrent;

  printf( "Buffer: " );

  do {

    if( RingBuffer[i] != INVALID_VALUE )

      printf( "%d ", RingBuffer[i] );

    i++;

    if( i == RINGBUFFER_SIZE )

      i = 0;

  } while( i != RingBufferCurrent );

  printf( "\n" );

}

int main()

{

  InitRingBuffer();

  PrintValues();

  printf( "%d  %d\n", MeanValue(), MeanValueOfLast() );

  AddValue( 5 );

  PrintValues();

  printf( "%d  %d\n", MeanValue(), MeanValueOfLast() );

  AddValue( 7 );

  PrintValues();

  printf( "%d  %d\n", MeanValue(), MeanValueOfLast() );

  AddValue( 9 );

  PrintValues();

  printf( "%d  %d\n", MeanValue(), MeanValueOfLast() );

  AddValue( 11 );

  PrintValues();

  printf( "%d  %d\n", MeanValue(), MeanValueOfLast() );

  AddValue( 20 );

  AddValue( 20 );

  AddValue( 20 );

  AddValue( 20 );

  AddValue( 20 );

  AddValue( 20 );

  AddValue( 20 );

  PrintValues();

  printf( "%d  %d\n", MeanValue(), MeanValueOfLast() );

}