bitOperation.h

/* Copyright (c) 2010, Cedric Stalder <cedric.stalder@gmail.com>
 *               2011-2012, Stefan Eilemann <eile@eyescale.ch>
 *                    2012, Daniel Nachbaur <danielnachbaur@gmail.com>
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License version 2.1 as published
 * by the Free Software Foundation.
 *
 * This library 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 Lesser General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifndef LUNCHBOX_BITOPERATION_H
#define LUNCHBOX_BITOPERATION_H

#include <lunchbox/compiler.h> // GCC version
#include <lunchbox/types.h>
#include <servus/uint128_t.h>

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4985) // inconsistent decl of ceil
#include <intrin.h>
#pragma warning(pop)
#elif defined __xlC__
#include <builtins.h>
#include <byteswap.h>
#elif defined(LB_GCC_4_3_OR_OLDER) && !defined(__clang__) && !defined(__APPLE__)
#include <byteswap.h>
#define LB_GCC_BSWAP_FUNCTION
#endif

namespace lunchbox
{
template <class T>
int32_t getIndexOfLastBit(T value);

template <class T>
void byteswap(T& value);

// Implementation
template <>
inline int32_t getIndexOfLastBit<uint32_t>(uint32_t value)
{
#ifdef __APPLE__
    return ::fls(value) - 1;
#elif defined __GNUC__
    return value ? (31 - __builtin_clz(value)) : -1;
#elif defined _MSC_VER
    unsigned long i = 0;
    return _BitScanReverse(&i, value) ? i : -1;
#else
    int32_t count = -1;
    while (value)
    {
        ++count;
        value >>= 1;
    }
    return count;
#endif
}

template <>
inline int32_t getIndexOfLastBit<uint64_t>(uint64_t value)
{
#ifdef __GNUC__
    return value ? (63 - __builtin_clzll(value)) : -1;
#elif defined _WIN64
    unsigned long i = 0;
    return _BitScanReverse64(&i, value) ? i : -1;
#else
    int32_t count = -1;
    while (value)
    {
        ++count;
        value >>= 1;
    }
    return count;
#endif
}

#if defined(__linux__) && defined(_LP64)
template <>
inline int32_t getIndexOfLastBit<unsigned long long>(unsigned long long value)
{
    return getIndexOfLastBit(static_cast<uint64_t>(value));
}
#endif
#ifdef __APPLE__
#ifdef _LP64
template <>
inline int32_t getIndexOfLastBit<unsigned long>(unsigned long value)
{
    return getIndexOfLastBit(static_cast<uint64_t>(value));
}
#else
template <>
inline int32_t getIndexOfLastBit<unsigned long>(unsigned long value)
{
    return getIndexOfLastBit(static_cast<uint32_t>(value));
}
#endif
#endif

template <>
inline void byteswap(void*&)
{ /*NOP*/
}
template <>
inline void byteswap(bool&)
{ /*NOP*/
}
template <>
inline void byteswap(char&)
{ /*NOP*/
}
template <>
inline void byteswap(signed char&)
{ /*NOP*/
}
template <>
inline void byteswap(unsigned char&)
{ /*NOP*/
}
template <>
inline void byteswap(std::string&)
{ /*NOP*/
}

template <>
inline void byteswap(uint32_t& value)
{
#ifdef _MSC_VER
    value = _byteswap_ulong(value);
#elif defined __xlC__
    __store4r(value, &value);
#elif defined LB_GCC_BSWAP_FUNCTION
    value = bswap_32(value);
#else
    value = __builtin_bswap32(value);
#endif
}

template <>
inline void byteswap(int32_t& value)
{
    byteswap(reinterpret_cast<uint32_t&>(value));
}

template <>
inline void byteswap(float& value)
{
    byteswap(reinterpret_cast<uint32_t&>(value));
}

template <>
inline void byteswap(uint16_t& value)
{
#ifdef _MSC_VER
    value = _byteswap_ushort(value);
#elif defined __xlC__
    __store2r(value, &value);
#else
    value = (uint16_t)(value >> 8) | (uint16_t)(value << 8);
#endif
}

template <>
inline void byteswap(int16_t& value)
{
    byteswap(reinterpret_cast<uint16_t&>(value));
}

#ifdef __APPLE__
template <>
inline void byteswap(unsigned long& value)
{
    byteswap(reinterpret_cast<unsigned long&>(value));
}
#endif

template <>
inline void byteswap(uint64_t& value)
{
#ifdef _MSC_VER
    value = _byteswap_uint64(value);
#elif defined __xlC__
    value = __bswap_constant_64(value);
#elif defined LB_GCC_BSWAP_FUNCTION
    value = bswap_64(value);
#else
    value = __builtin_bswap64(value);
#endif
}

template <>
inline void byteswap(int64_t& value)
{
    byteswap(reinterpret_cast<uint64_t&>(value));
}

template <>
inline void byteswap(double& value)
{
    byteswap(reinterpret_cast<uint64_t&>(value));
}

template <>
inline void byteswap(servus::uint128_t& value)
{
    byteswap(value.high());
    byteswap(value.low());
}

template <typename T>
inline void byteswap(typename std::vector<T>& value)
{
    for (size_t i = 0; i < value.size(); ++i)
        byteswap(value[i]);
}
}
#endif // LUNCHBOX_BITOPERATION_H