use CRC inside py_aff3ct

[yunl140]

Thank you so much for this super helpful project.

I am trying to modify from https://github.com/aff3ct/py_aff3ct/blob/master/examples/full_python/bfer_polar.py to use the CA-SCL decoding with some crc polynomial. I rarely worked with c++ and I'm not familiar at all with the binding stuff... I could not find any wrapped module for CRCs, and I'm not sure how to construct a proper aff3ct::module::CRC type argument for the decoder Decoder_polar_SCL_naive_CA. Any hints on this?

[rtajan]

Hi,

Thank you for your interest for AFF3CT and py_aff3ct.

I have added CRC to modules wrapped by default.
Within the bfer_polar example, something like this should work now:

K_crc = 512
K = K_crc - 24
...
crc = aff3ct.module.crc.CRC_polynomial_fast(K,'24-5GA') # Instanciate CRC
dec = aff3ct.module.decoder.Decoder_polar_SCL_fast_CA_sys(K_crc,N,L,frozen_bits,crc) # Use CRC for the SCL CA

crc["build        ::U_K1"].bind(src["generate   ::U_K "])
enc["encode       ::U_K "].bind(crc["build      ::U_K2"])
...
crc["extract      ::V_K1"].bind(dec["decode_siho::V_K "])
mnt["check_errors ::U   "].bind(src["generate   ::U_K "])
mnt["check_errors ::V   "].bind(crc["extract    ::V_K2"])

[yunl140]

Yes the CRC module works. Just one more remark: in calculating error rate, I think

crc["extract      ::V_K1"].bind(dec["decode_siho::V_K "])
mnt["check_errors ::V   "].bind(crc["extract      ::V_K2"])

is the correct way we're looking for.

[rtajan]

I have edited my answer so that the solution seems complete now.

[yunl140]

The following version works now (changed fbgen and enc as well). Thank you!

K_crc = 512
K = K_crc - 24
...
fbgen = aff3ct.tools.frozenbits_generator.Frozenbits_generator_GA_Arikan(K_crc, N)
...
crc = aff3ct.module.crc.CRC_polynomial_fast(K,'24-5GA')
enc = aff3ct.module.encoder.Encoder_polar_sys(K_crc,N,frozen_bits)
dec = aff3ct.module.decoder.Decoder_polar_SCL_fast_CA_sys(K_crc,N,L,frozen_bits,crc) # Use CRC for the SCL CA
...
crc["build        ::U_K1"].bind(src["generate   ::U_K "])
enc["encode       ::U_K "].bind(crc["build      ::U_K2"])
...
crc["extract      ::V_K1"].bind(dec["decode_siho::V_K "])
mnt["check_errors ::U   "].bind(src["generate   ::U_K "])
mnt["check_errors ::V   "].bind(crc["extract    ::V_K2"])