Handle functions with more than nine parameters

[rtATvw]

atom.c

static unsigned get_arity_magnitude(int n) {
    unsigned magnitude = 0;
    for (int i = n; i >= 1; i /= 10) {
        magnitude++;
    }
    if (n == 0)
        return 1;
    return magnitude;
}

static void arity_to_str(int n, unsigned magnitude, char *ptr) {
  for (int i = magnitude - 1; i >= 0; i--) {
    ptr[i] = '0' + n % 10;
    n /= 10;
  }
  ptr[magnitude] = '\0';
}

void atom_write_mfa(char *buf, size_t buf_size, AtomString module, AtomString function, unsigned int arity)
{
    size_t module_name_len = atom_string_len(module);
    memcpy(buf, atom_string_data(module), module_name_len);

    buf[module_name_len] = ':';

    int arity_magnitude = get_arity_magnitude(arity);

    size_t function_name_len = atom_string_len(function);
    if (UNLIKELY((module_name_len + function_name_len + arity_magnitude + 3 > buf_size))) {
        fprintf(stderr, "Insufficient room to write mfa.\n");
        AVM_ABORT();
    }
    memcpy(buf + module_name_len + 1, atom_string_data(function), function_name_len);

    buf[module_name_len + function_name_len + 1] = '/';
    arity_to_str(arity, arity_magnitude, buf + module_name_len + function_name_len + 2);
}

nifs.c

const struct Nif *nifs_get(AtomString module, AtomString function, int arity)
{
    char nifname[MAX_NIF_NAME_LEN];
    
    atom_write_mfa(nifname, MAX_NIF_NAME_LEN, module, function, arity);

    const NifNameAndNifPtr *nameAndPtr = nif_in_word_set(nifname, strlen(nifname));
    if (!nameAndPtr) {
        return platform_nifs_get_nif(nifname);
    }

    return nameAndPtr->nif;
}