// -*- C++ -*-

// Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library 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 3, or (at your option) any later
// version.

// 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
// General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file parallel/compatibility.h
 *  @brief Compatibility layer, mostly concerned with atomic operations.
 *  This file is a GNU parallel extension to the Standard C++ Library.
 */

// Written by Felix Putze.

#ifndef _GLIBCXX_PARALLEL_COMPATIBILITY_H
#define _GLIBCXX_PARALLEL_COMPATIBILITY_H 1

#include <parallel/types.h>
#include <parallel/base.h>

#if defined(__SUNPRO_CC) && defined(__sparc)
#include <sys/atomic.h>
#endif

#if !defined(_WIN32) || defined (__CYGWIN__)
#include <sched.h>
#endif

#if defined(_MSC_VER)
#include <Windows.h>
#include <intrin.h>
#undef max
#undef min
#endif

#ifdef __MINGW32__
// Including <windows.h> will drag in all the windows32 names.  Since
// that can cause user code portability problems, we just declare the
// one needed function here.
extern "C"
__attribute((dllimport)) void __attribute__((stdcall)) Sleep (unsigned long);
#endif

namespace __gnu_parallel
{
#if defined(__ICC)
  template<typename _MustBeInt = int>
  int32_t __faa32(int32_t* __x, int32_t __inc)
  {
    asm volatile("lock xadd %0,%1"
                 : "=__r" (__inc), "=__m" (*__x)
                 : "0" (__inc)
                 : "memory");
    return __inc;
  }
#if defined(__x86_64)
  template<typename _MustBeInt = int>
  int64_t __faa64(int64_t* __x, int64_t __inc)
  {
    asm volatile("lock xadd %0,%1"
                 : "=__r" (__inc), "=__m" (*__x)
                 : "0" (__inc)
                 : "memory");
    return __inc;
  }
#endif
#endif

  // atomic functions only work on integers

  /** @brief Add a value to a variable, atomically.
   *
   *  Implementation is heavily platform-dependent.
   *  @param __ptr Pointer to a 32-bit signed integer.
   *  @param __addend Value to add.
   */
  inline int32_t
  __fetch_and_add_32(volatile int32_t* __ptr, int32_t __addend)
  {
#if defined(__ICC)      //x86 version
    return _InterlockedExchangeAdd((void*)__ptr, __addend);
#elif defined(__ECC)    //IA-64 version
    return _InterlockedExchangeAdd((void*)__ptr, __addend);
#elif defined(__ICL) || defined(_MSC_VER)
    return _InterlockedExchangeAdd(reinterpret_cast<volatile long*>(__ptr),
                                   __addend);
#elif defined(__GNUC__)
    return __sync_fetch_and_add(__ptr, __addend);
#elif defined(__SUNPRO_CC) && defined(__sparc)
    volatile int32_t __before, __after;
    do
      {
        __before = *__ptr;
        __after = __before + __addend;
      } while (atomic_cas_32((volatile unsigned int*)__ptr, __before,
                             __after) != __before);
    return __before;
#else   //fallback, slow
#pragma message("slow __fetch_and_add_32")
    int32_t __res;
#pragma omp critical
    {
      __res = *__ptr;
      *(__ptr) += __addend;
    }
    return __res;
#endif
  }

  /** @brief Add a value to a variable, atomically.
   *
   *  Implementation is heavily platform-dependent.
   *  @param __ptr Pointer to a 64-bit signed integer.
   *  @param __addend Value to add.
   */
  inline int64_t
  __fetch_and_add_64(volatile int64_t* __ptr, int64_t __addend)
  {
#if defined(__ICC) && defined(__x86_64) //x86 version
    return __faa64<int>((int64_t*)__ptr, __addend);
#elif defined(__ECC)    //IA-64 version
    return _InterlockedExchangeAdd64((void*)__ptr, __addend);
#elif defined(__ICL) || defined(_MSC_VER)
#ifndef _WIN64
    _GLIBCXX_PARALLEL_ASSERT(false);    //not available in this case
    return 0;
#else
    return _InterlockedExchangeAdd64(__ptr, __addend);
#endif
#elif defined(__GNUC__) && defined(__x86_64)
    return __sync_fetch_and_add(__ptr, __addend);
#elif defined(__GNUC__) && defined(__i386) &&                   \
  (defined(__i686) || defined(__pentium4) || defined(__athlon))
    return __sync_fetch_and_add(__ptr, __addend);
#elif defined(__SUNPRO_CC) && defined(__sparc)
    volatile int64_t __before, __after;
    do
      {
        __before = *__ptr;
        __after = __before + __addend;
      } while (atomic_cas_64((volatile unsigned long long*)__ptr, __before,
                             __after) != __before);
    return __before;
#else   //fallback, slow
#if defined(__GNUC__) && defined(__i386)
    // XXX doesn'__t work with -march=native
    //#warning "please compile with -march=i686 or better"
#endif
#pragma message("slow __fetch_and_add_64")
    int64_t __res;
#pragma omp critical
    {
      __res = *__ptr;
      *(__ptr) += __addend;
    }
    return __res;
#endif
  }

  /** @brief Add a value to a variable, atomically.
   *
   *  Implementation is heavily platform-dependent.
   *  @param __ptr Pointer to a signed integer.
   *  @param __addend Value to add.
   */
  template<typename _Tp>
  inline _Tp
  __fetch_and_add(volatile _Tp* __ptr, _Tp __addend)
  {
    if (sizeof(_Tp) == sizeof(int32_t))
      return
        (_Tp)__fetch_and_add_32((volatile int32_t*) __ptr, (int32_t)__addend);
    else if (sizeof(_Tp) == sizeof(int64_t))
      return
        (_Tp)__fetch_and_add_64((volatile int64_t*) __ptr, (int64_t)__addend);
    else
      _GLIBCXX_PARALLEL_ASSERT(false);
  }


#if defined(__ICC)

  template<typename _MustBeInt = int>
  inline int32_t
  __cas32(volatile int32_t* __ptr, int32_t __old, int32_t __nw)
  {
    int32_t __before;
    __asm__ __volatile__("lock; cmpxchgl %1,%2"
                         : "=a"(__before)
                         : "q"(__nw), "__m"(*(volatile long long*)(__ptr)),
                               "0"(__old)
                         : "memory");
    return __before;
  }

#if defined(__x86_64)
  template<typename _MustBeInt = int>
  inline int64_t
  __cas64(volatile int64_t *__ptr, int64_t __old, int64_t __nw)
  {
    int64_t __before;
    __asm__ __volatile__("lock; cmpxchgq %1,%2"
                         : "=a"(__before)
                         : "q"(__nw), "__m"(*(volatile long long*)(__ptr)),
                               "0"(__old)
                         : "memory");
    return __before;
  }
#endif

#endif

  /** @brief Compare @c *__ptr and @c __comparand. If equal, let @c
   * *__ptr=__replacement and return @c true, return @c false otherwise.
   *
   *  Implementation is heavily platform-dependent.
   *  @param __ptr Pointer to 32-bit signed integer.
   *  @param __comparand Compare value.
   *  @param __replacement Replacement value.
   */
  inline bool
  __compare_and_swap_32(volatile int32_t* __ptr, int32_t __comparand,
                        int32_t __replacement)
  {
#if defined(__ICC)      //x86 version
    return _InterlockedCompareExchange((void*)__ptr, __replacement,
                                       __comparand) == __comparand;
#elif defined(__ECC)    //IA-64 version
    return _InterlockedCompareExchange((void*)__ptr, __replacement,
                                       __comparand) == __comparand;
#elif defined(__ICL) || defined(_MSC_VER)
    return _InterlockedCompareExchange(
               reinterpret_cast<volatile long*>(__ptr),
               __replacement, __comparand)
             == __comparand;
#elif defined(__GNUC__)
    return __sync_bool_compare_and_swap(__ptr, __comparand, __replacement);
#elif defined(__SUNPRO_CC) && defined(__sparc)
    return atomic_cas_32((volatile unsigned int*)__ptr, __comparand,
                         __replacement) == __comparand;
#else
#pragma message("slow __compare_and_swap_32")
    bool __res = false;
#pragma omp critical
    {
      if (*__ptr == __comparand)
        {
          *__ptr = __replacement;
          __res = true;
        }
    }
    return __res;
#endif
  }

  /** @brief Compare @c *__ptr and @c __comparand. If equal, let @c
   * *__ptr=__replacement and return @c true, return @c false otherwise.
   *
   *  Implementation is heavily platform-dependent.
   *  @param __ptr Pointer to 64-bit signed integer.
   *  @param __comparand Compare value.
   *  @param __replacement Replacement value.
   */
  inline bool
  __compare_and_swap_64(volatile int64_t* __ptr, int64_t __comparand,
                        int64_t __replacement)
  {
#if defined(__ICC) && defined(__x86_64) //x86 version
    return __cas64<int>(__ptr, __comparand, __replacement) == __comparand;
#elif defined(__ECC)    //IA-64 version
    return _InterlockedCompareExchange64((void*)__ptr, __replacement,
                                         __comparand) == __comparand;
#elif defined(__ICL) || defined(_MSC_VER)
#ifndef _WIN64
    _GLIBCXX_PARALLEL_ASSERT(false);    //not available in this case
    return 0;
#else
    return _InterlockedCompareExchange64(__ptr, __replacement,
                                         __comparand) == __comparand;
#endif

#elif defined(__GNUC__) && defined(__x86_64)
    return __sync_bool_compare_and_swap(__ptr, __comparand, __replacement);
#elif defined(__GNUC__) && defined(__i386) &&                   \
  (defined(__i686) || defined(__pentium4) || defined(__athlon))
    return __sync_bool_compare_and_swap(__ptr, __comparand, __replacement);
#elif defined(__SUNPRO_CC) && defined(__sparc)
    return atomic_cas_64((volatile unsigned long long*)__ptr,
                         __comparand, __replacement) == __comparand;
#else
#if defined(__GNUC__) && defined(__i386)
    // XXX -march=native
    //#warning "please compile with -march=i686 or better"
#endif
#pragma message("slow __compare_and_swap_64")
    bool __res = false;
#pragma omp critical
    {
      if (*__ptr == __comparand)
        {
          *__ptr = __replacement;
          __res = true;
        }
    }
    return __res;
#endif
  }

  /** @brief Compare @c *__ptr and @c __comparand. If equal, let @c
   * *__ptr=__replacement and return @c true, return @c false otherwise.
   *
   *  Implementation is heavily platform-dependent.
   *  @param __ptr Pointer to signed integer.
   *  @param __comparand Compare value.
   *  @param __replacement Replacement value. */
  template<typename _Tp>
  inline bool
  __compare_and_swap(volatile _Tp* __ptr, _Tp __comparand, _Tp __replacement)
  {
    if (sizeof(_Tp) == sizeof(int32_t))
      return __compare_and_swap_32((volatile int32_t*) __ptr,
                                   (int32_t)__comparand,
                                   (int32_t)__replacement);
    else if (sizeof(_Tp) == sizeof(int64_t))
      return __compare_and_swap_64((volatile int64_t*) __ptr,
                                   (int64_t)__comparand,
                                   (int64_t)__replacement);
    else
      _GLIBCXX_PARALLEL_ASSERT(false);
  }

  /** @brief Yield the control to another thread, without waiting for
      the end to the time slice. */
  inline void
  __yield()
  {
#if defined (_WIN32) && !defined (__CYGWIN__)
    Sleep(0);
#else
    sched_yield();
#endif
  }
} // end namespace

#endif /* _GLIBCXX_PARALLEL_COMPATIBILITY_H */
