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ZBasic System Library

ZBasic Microcontrollers

Rocksoft Model Parameters for Common CRC Algorithms

The parameters are included in the table above for the CRC-32 algorithm but, of course, they must be

used with the CRC32() function. The CHECK value is the CRC result for the string of characters

Additional information on CRC calculations may be found in many places on the Internet. One useful site

that implements a CRC calculator is http://www.zorc.breitbandkatze.de/crc.html. If you don’t know the

parameters required for a particular CRC, you may be able to deduce the correct parameters by using the

calculator if you have a sample message and its CRC value. One of the variables available in the CRC

calculator on the web page mentioned is “direct” vs. “nondirect”. This implementation uses the “direct”

Dim data(1 to 20) as Byte

Dim crc as UnsignedInteger

' compute the CRC using the CRC-16 algorithm

crc = CRC16(data, 10, &H8005, &H0000, zxCRCRefIn Or zxCRCRefOut)

This function is not available in BasicX compatibility mode. Also, on ZX models that are based on the

ATmega32 processor (e.g. the ZX-24) this function is implemented in “user code” (as opposed to being

part of the VM) and is consequently slower than on other ZX models and ZBasic devices generally.