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/*
* Copyright (c) 2003 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.
*/
#ifndef __INTMATH_H__
#define __INTMATH_H__
// Returns the prime number one less than n.
int PrevPrime(int n);
// Determine if a number is prime
inline bool
IsPrime(int n)
{
int i;
if (n == 2 || n == 3)
return true;
// Don't try every odd number to prove if it is a prime.
// Toggle between every 2nd and 4th number.
// (This is because every 6th odd number is divisible by 3.)
for (i = 5; i*i <= n; i += 6) {
if (((n % i) == 0 ) || ((n % (i + 2)) == 0) ) {
return false;
}
}
return true;
}
inline unsigned
LeastSigBit(unsigned n)
{ return n & ~(n - 1); }
inline bool
IsPowerOf2(unsigned n)
{ return n != 0 && LeastSigBit(n) == n; }
inline int
FloorLog2(unsigned x)
{
if (x == 0)
return -1;
int y = 0;
if (x & 0xffff0000) { y += 16; x >>= 16; }
if (x & 0x0000ff00) { y += 8; x >>= 8; }
if (x & 0x000000f0) { y += 4; x >>= 4; }
if (x & 0x0000000c) { y += 2; x >>= 2; }
if (x & 0x00000002) { y += 1; }
return y;
}
inline int
CeilLog2(unsigned n)
{ return FloorLog2(n-1)+1; }
inline unsigned
FloorPow2(unsigned n)
{ return 1 << FloorLog2(n); }
inline unsigned
CeilPow2(unsigned n)
{ return 1 << CeilLog2(n); }
inline bool
IsHex(char c)
{ return (c >= '0' && c <= '9' ||
c >= 'A' && c <= 'F' ||
c >= 'a' && c <= 'f');
}
inline bool
IsOct(char c)
{ return (c >= '0' && c <= '7'); }
inline bool
IsDec(char c)
{ return (c >= '0' && c <= '9'); }
inline int
Hex2Int(char c)
{
if (c >= '0' && c <= '9')
return (c - '0');
if(c >= 'A' && c <= 'F')
return (c - 'A') + 10;
if (c >= 'a' && c <= 'f')
return (c - 'a') + 10;
return 0;
}
#endif // __INTMATH_H__
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