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Diffstat (limited to 'base/intmath.cc')
-rw-r--r-- | base/intmath.cc | 58 |
1 files changed, 0 insertions, 58 deletions
diff --git a/base/intmath.cc b/base/intmath.cc deleted file mode 100644 index f1c1651ba..000000000 --- a/base/intmath.cc +++ /dev/null @@ -1,58 +0,0 @@ -/* - * Copyright (c) 2001, 2003-2005 The Regents of The University of Michigan - * All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions are - * met: redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer; - * redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution; - * neither the name of the copyright holders nor the names of its - * contributors may be used to endorse or promote products derived from - * this software without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS - * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT - * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR - * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT - * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, - * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT - * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, - * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY - * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT - * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE - * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. - */ - -#include "base/intmath.hh" - -int -prevPrime(int n) -{ - int decr; - - // If the number is even, let's start with the previous odd number. - if (!(n & 1)) - --n; - - // Lets test for divisibility by 3. Then we will be able to easily - // avoid numbers that are divisible by 3 in the future. - decr = n % 3; - if (decr == 0) { - n -= 2; - decr = 2; - } - else if (decr == 1) - decr = 4; - - for (;;) { - if (isPrime(n)) - return n; - n -= decr; - // Toggle between 2 and 4 to prevent trying numbers that are known - // to be divisible by 3. - decr = 6 - decr; - } -} |