in c_src/hyper_carray.c [271:284]
static ERL_NIF_TERM encode_registers(ErlNifEnv * env, int argc,
const ERL_NIF_TERM argv[])
{
carray_ptr arr = NULL;
HYPER_CARRAY_OR_BADARG(argv[0], arr);
size_t nbytes = arr->size;
ERL_NIF_TERM bin;
unsigned char *buf = enif_make_new_binary(env, nbytes, &bin);
memcpy(buf, arr->items, nbytes);
return bin;
}