Device 18F2520
 XTAL = 4
 ALL_DIGITAL = TRUE
 polynoom var Byte  
 crc var Byte
 dat var DWord
 loop var Byte
 




'**************************** subroutines ********************************
calc_crc:
crc=0
For loop = 1 To 6
    dat = stream [loop]
     For x = 0 To 7
        If (crc & $80) > 0  Then
            polynoom = $9B
        Else
            polynoom = $00
        EndIf
        crc = (crc &~$80)<<1                  '& = and    ~ = not
        If (dat & $80)>0 Then crc = crc | 1   '| = or
        crc = crc ^ polynoom                  '^ = xor
        dat = dat<<1
    Next x   
Next loop
Return