blob: e161dd801ed9c09d1d2f4a17b19cd271ea31abb7 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
#!/usr/bin/env python2.6
#
# Copyright (C) 2011 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
#
# Generates a table of prime numbers for use in BasicHashtable.cpp.
#
# Each prime is chosen such that it is a little more than twice as large as
# the previous prime in the table. This makes it easier to choose a new
# hashtable size when the underlying array is grown by as nominal factor
# of two each time.
#
def is_odd_prime(n):
limit = (n - 1) / 2
d = 3
while d <= limit:
if n % d == 0:
return False
d += 2
return True
print "static size_t PRIMES[] = {"
n = 5
max = 2**31 - 1
while n < max:
print " %d," % (n)
n = n * 2 + 1
while not is_odd_prime(n):
n += 2
print " 0,"
print "};"
|
