47 lines
1.2 KiB
Python
Executable file
47 lines
1.2 KiB
Python
Executable file
#!/usr/bin/env python2.6
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#
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# Copyright (C) 2011 The Android Open Source Project
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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#
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# Generates a table of prime numbers for use in BasicHashtable.cpp.
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#
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# Each prime is chosen such that it is a little more than twice as large as
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# the previous prime in the table. This makes it easier to choose a new
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# hashtable size when the underlying array is grown by as nominal factor
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# of two each time.
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#
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def is_odd_prime(n):
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limit = (n - 1) / 2
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d = 3
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while d <= limit:
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if n % d == 0:
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return False
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d += 2
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return True
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print "static size_t PRIMES[] = {"
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n = 5
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max = 2**31 - 1
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while n < max:
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print " %d," % (n)
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n = n * 2 + 1
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while not is_odd_prime(n):
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n += 2
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print " 0,"
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print "};"
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