#define BLOCK_SIZE 10
#define NOT_YET -1.0

float mv_avg( unsigned int sample )
{
   static int ptr = 0;
   static int count = 1;
   static long total = 0;
   static unsigned int block[BLOCK_SIZE - 1];

   if( count == BLOCK_SIZE ) /* start returning averaged
                                    results on Nth sample */
   {  
     total += sample - block[ptr];   
     block[ptr] = sample;
     ptr = ( ptr < BLOCK_SIZE - 1 ) ? ptr++ : 0;
     return ( ( float ) total / BLOCK_SIZE );    
   }
   else
   { 
     count++;
     block[ptr++] = sample;
     total += sample;
     return ( NOT_YET );
   } 
}