Doing NMEA command sequences with zsh ... ??!!

[meino.cramer@xxxxxx]

Hi,

To my embedded system (which runs zsh on Gentoo Linux ;) ) I have
atteched an GPS receiver chip.
This chip spits out NMEA sentences to an UART and is capable of
receiving NMEA command seqyences.

An NMEA command sequence consist of
$<commandname><parameter,nextparameter,....><*><checksum>

The checksum is the binary XOR of all characters between '$' and '*'.
This checksum is given a an hexadecimal number.

Since it is an embedded system, I would prefer to calculate this
checksum with zsh only since it already runs if I am logged in.

Is that possible in any way?

Thank you very much in advance for any help!
Best regards,
mcc