Function semq_codec_unpack 

pub unsafe extern "C" fn semq_codec_unpack(
    codec: *const semq_codec_t,
    enc: *const semq_encoding_t,
    out: *mut u8,
    err: *mut semq_error_t,
) -> semq_status_t

Symbols, n x units_per_row bytes, one per unit.