Wrapper for the horus binary encoder functions

[darksidelemm]

Would be useful to have a python library which allows generation of horus binary packets, output either as audio, IQ, or perhaps something that can be fed into rpitx.

It looks like the horus_l2_encode_tx_packet function is available within libhorus, so we can probably call that from python using ctypes.

[darksidelemm]

Starting to make a stab at this.

• ctypes wrappers for the horus_l2 encode/decode functions.
• Wrapper for CRC16 functions (or can probably just use the existing crcmod ones?
• Generic decoder wrapper, which checks the checksum and only outputs if the checksum passes (not sure what we'll use this for, but might be handy)
• Horus v2 packet encoder function.
• Helper functions to convert encoded packets to useful output formats.
• Maybe a fsk_mod wrapper to encode packets to audio output?

[darksidelemm]

More progress made on this. We now have functions to encode a horus v2 packet, and to convert bytes into 4FSK symbols, and one-bit-per-byte representation for modulating using fsk_mod.
Currently using the checksum calculations from horusdemodlib.checksums, which uses crcmod. This way i dont need to change anything when I switch out crcmod for crc.