Rx validation of checksum

Code:

---

CALC_Checksum1:
    Checksum1 = 0
    WORD_HOLD = 0
    for i = 3 to MAX_LEN
      Word_Hold = Word_Hold + tx_data1(i)
    next
    Checksum1 = WORD_HOLD.byte0 ^ $FF
    RETURN

CALC_Checksum2:
    Checksum2 = 0
    for i = 3 to MAX_LEN
      Checksum2 = Checksum2 + tx_data1(i)
    next
    Checksum2 =  Checksum2 // 256
  'Checksum2 = -Checksum2
    RETURN

---

the above routines i pieced together from other posts here to genereate a checksum for transimitted data packets.

to validate on the received end, do i run the same routine and compare values to see if the checksums are equal?

Yes you do.

But instead of this double checksum i'd prefer the 16 bit CRC check. More reliable.

Look here for the fast sub routine from the usual suspect:

http://www.picbasic.co.uk/forum/showthread.php?t=11790

Ioannis

Thanks Ioannis.

Indeed, DT's looks quite fast. a handy routine i'll "borrow" into me tool box.

btw, i would use [either or] of my sub-routines, not both at the same time.

Cheers!