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llvm-mirror/include/Support/MathExtras.h
Brian Gaeke 5d29845f19 Cygwin defines log2 as a macro. Undef it here IFF it has already been defined,
so that we always get the inline function instead. Remember, kids, like it says
in the GCC manual, "An Inline Function is As Fast As a Macro."

llvm-svn: 11815
2004-02-25 01:53:45 +00:00

45 lines
1.0 KiB
C++

//===-- Support/MathExtras.h - Useful math functions ------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains some functions that are useful for math stuff.
//
//===----------------------------------------------------------------------===//
#ifndef SUPPORT_MATHEXTRAS_H
#define SUPPORT_MATHEXTRAS_H
#include "Support/DataTypes.h"
namespace llvm {
#if defined(log2)
# undef log2
#endif
inline unsigned log2(uint64_t C) {
unsigned getPow;
for (getPow = 0; C > 1; ++getPow)
C >>= 1;
return getPow;
}
inline bool isPowerOf2(int64_t C, unsigned &getPow) {
if (C < 0) C = -C;
if (C > 0 && C == (C & ~(C - 1))) {
getPow = log2(static_cast<uint64_t>(C));
return true;
}
return false;
}
} // End llvm namespace
#endif