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// utility functions
// Copyright (C) 2005-2012 Tim Blechmann
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; see the file COPYING. If not, write to
// the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.
#ifndef UTILITIES_UTILS_HPP
#define UTILITIES_UTILS_HPP
#include <cstddef>
#include <cassert>
#include <type_traits>
#include <boost/static_assert.hpp>
#include "boost/noncopyable.hpp"
#include <boost/intrusive_ptr.hpp>
#include <boost/detail/atomic_count.hpp>
#include "branch_hints.hpp"
typedef unsigned int uint;
#include "malloc_aligned.hpp"
#include "function_attributes.h"
namespace nova {
/* we're using some member of the boost namespace */
using boost::noncopyable;
using boost::intrusive_ptr;
/* some basic math functions */
inline bool ispoweroftwo(int i)
{
return (i & (i - 1)) == 0;
}
template <unsigned int n>
struct is_power_of_two
{
static const bool val = (n%2==0) && (is_power_of_two<(n>>1)>::val);
};
template <>
struct is_power_of_two<2>
{
static const bool val = true;
};
inline int log2(int n)
{
if (unlikely(n <= 0))
return(0);
#ifdef __GNUC__
return sizeof(int) * __CHAR_BIT__ - 1 - __builtin_clz( n );
#else
int r = -1;
while (n)
{
r++;
n >>= 1;
}
return r;
#endif
}
inline int nextpoweroftwo(int n)
{
n = n - 1;
const uint bitspace = sizeof(int) * 8 / 2;
for (uint i = 1; i != bitspace; i *= 2)
n = n | (n >> i);
return n + 1;
}
using std::size_t;
/** \brief base class for a callback function */
template <typename t>
class runnable
{
public:
virtual ~runnable(void)
{}
virtual t run(void) = 0;
};
/** \brief tag for denoting a deleteable class */
class deleteable
{};
template <class T>
struct default_deleter
{
void operator()(T * t)
{
delete t;
}
};
struct delayed_deleter
{
template <typename T>
inline void operator()(T *);
};
struct checked_deleter
{
template<class T>
void operator()(T * x) const
{
boost::checked_delete(x);
}
};
template <typename deleter = checked_deleter >
struct intrusive_refcountable:
public noncopyable,
public deleter
{
intrusive_refcountable(void):
use_count_(0)
{}
virtual ~intrusive_refcountable(void)
{}
void add_ref(void)
{
++use_count_;
}
void release(void)
{
if(--use_count_ == 0)
deleter::operator()(this);
}
inline friend void intrusive_ptr_add_ref(intrusive_refcountable * p)
{
p->add_ref();
}
inline friend void intrusive_ptr_release(intrusive_refcountable * p)
{
p->release();
}
boost::detail::atomic_count use_count_;
};
template <class t, class compare = std::less<t> >
struct compare_by_instance
{
bool operator()(const t * lhs, const t * rhs)
{
assert(lhs and rhs);
compare cmp;
return cmp(*lhs, *rhs);
}
};
PURE inline std::size_t string_hash(const char * str)
{
std::size_t ret = 0;
// sdbm hash ... later try another function!
int c;
while ((c = *str++))
ret = c + (ret << 6) + (ret << 16) - ret;
return ret;
}
struct linear_allocator
{
linear_allocator(char * chunk):
chunk(chunk)
{}
template <typename T>
T * alloc(int count = 1)
{
T * ret = reinterpret_cast<T*>(chunk);
chunk += count * sizeof(T);
return ret;
}
private:
char * chunk;
};
} /* namespace nova */
#endif /* UTILITIES_UTILS_HPP */
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