1#!/usr/bin/env python2.6
2#
3# Copyright (C) 2011 The Android Open Source Project
4#
5# Licensed under the Apache License, Version 2.0 (the "License");
6# you may not use this file except in compliance with the License.
7# You may obtain a copy of the License at
8#
9#      http://www.apache.org/licenses/LICENSE-2.0
10#
11# Unless required by applicable law or agreed to in writing, software
12# distributed under the License is distributed on an "AS IS" BASIS,
13# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14# See the License for the specific language governing permissions and
15# limitations under the License.
16#
17
18#
19# Generates a table of prime numbers for use in BasicHashtable.cpp.
20#
21# Each prime is chosen such that it is a little more than twice as large as
22# the previous prime in the table.  This makes it easier to choose a new
23# hashtable size when the underlying array is grown by as nominal factor
24# of two each time.
25#
26
27def is_odd_prime(n):
28  limit = (n - 1) / 2
29  d = 3
30  while d <= limit:
31    if n % d == 0:
32      return False
33    d += 2
34  return True
35
36print "static size_t PRIMES[] = {"
37
38n = 5
39max = 2**31 - 1
40while n < max:
41  print "    %d," % (n)
42  n = n * 2 + 1
43  while not is_odd_prime(n):
44    n += 2
45
46print "    0,"
47print "};"
48