Optimizing CRC16 routine.

[Mike, K8LH]

Greetings Henrik,

Is there a chance you have a lot of overhead associated with array handling? Have you looked at the assembly language generated by that routine?

I checked out the inner loop using BoostC and found worst case cycle times of 123 cycles in a "for/next" loop and 100 cycles in a "do/while" loop.

Cheerful regards, Mike

  crcword ^= work;         // 123 cycles (BoostC)
  for(char i=0; i<8; i++)  //                      
  { crcword >>= 1;         //
    if(status.C)           //
      crcword ^= 0x0A01;   //
  }

  crcword ^= work; i = 0;   // 100 cycles (BoostC)
  do {                      //
    crcword >>= 1;          //
    if(status.C)            //
      crcword ^= 0x0A01;    //
    i++;                    //
  } while(i.3 == 0);        //