Merge commit '536dea9d61a032e64bbe584a97463c6638ead009' into HEAD

Change-Id: I5c469a4b738629d99d721cad7ded02d6c35f56d5

1 files changed, 47 insertions, 0 deletions

diff --git a/libutils/primes.py b/libutils/primes.py
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+++ b/libutils/primes.py
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+#!/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 "};"