/* -*- C -*-

// -------------------------------------------------------------------

// Atomic primitives

// Copyright (c) 2008  Leon Bottou. All rights reserved

//

// Permission is hereby granted, free of charge, to any person obtaining

// a copy of this software and associated documentation files (the

// "Software"), to deal in the Software without restriction, including

// without limitation the rights to use, copy, modify, merge, publish,

// distribute, sublicense, and/or sell copies of the Software, and to

// permit persons to whom the Software is furnished to do so, subject to

// the following conditions:

//

// The above copyright notice and this permission notice shall be

// included in all copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY

// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,

// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

//

// ------------------------------------------------------------------- */

#ifndef ATOMIC_H

#define ATOMIC_H

#ifdef HAVE_CONFIG_H

# include "config.h"

#endif

/* This file defines macros or functions performing

// the following atomic operations with a full memory barrier. 

//

//   int atomicIncrement(int volatile *var) 

//   { *var += 1; return *var; } 

//   

//   int atomicDecrement(int volatile *var);

//   { *var -= 1; return *var; } 

//   

//   int atomicCompareAndSwap(int volatile *var, int oldval, int newval);

//   { int val = *var; if (val == oldval) { *var = newval };  returl val; }

//   

//   int atomicExchange(int volatile *var, int val);

//   { int tmp = *var; *var = val; return tmp; }

//   

//   void* atomicExchangePointer(void* volatile *var, int val);

//   { void* tmp = *var; *var = val; return tmp; }

*/

#ifdef __cplusplus

extern "C" {

#endif

#if !defined(ATOMIC_MACROS) && defined(_WIN64)

# define ATOMIC_MACROS "WIN64"

# include <windows.h>

# define atomicIncrement(var) \

  (int)(InterlockedIncrement((LONG volatile*)(var)))

# define atomicDecrement(var) \

  (int)(InterlockedDecrement((LONG volatile*)(var)))

# define atomicCompareAndSwap(var,ov,nv) \

  (InterlockedCompareExchange((LONG volatile*)(var),(LONG)(nv),(LONG)(ov)))

# define atomicExchange(var,nv) \

  (int)(InterlockedExchange((LONG volatile*)(var),(LONG)(nv)))

# define atomicExchangePointer(var,nv) \

  (void*)(InterlockedExchangePointer((PVOID volatile*)(var),(PVOID)(nv)))

#endif

#if !defined(ATOMIC_MACROS) && defined(_WIN32)

# define ATOMIC_MACROS "WIN32"

# include <windows.h>

# define atomicIncrement(var) \

  (int)(InterlockedIncrement((LONG volatile*)(var)))

# define atomicDecrement(var) \

  (int)(InterlockedDecrement((LONG volatile*)(var)))

# define atomicCompareAndSwap(var,ov,nv) \

  (InterlockedCompareExchange((LONG volatile*)(var),(LONG)(nv),(LONG)(ov)))

# define atomicExchange(var,nv) \

  (int)(InterlockedExchange((LONG volatile*)(var),(LONG)(nv)))

# define atomicExchangePointer(var,nv) \

  (void*)(InterlockedExchange((LONG volatile*)(var),(LONG)(nv)))

#endif

#if !defined(ATOMIC_MACROS) && defined(HAVE_INTEL_ATOMIC_BUILTINS)

# define ATOMIC_MACROS "INTEL"

# define atomicIncrement(var) \

  (__sync_add_and_fetch((int volatile *)(var), 1))

# define atomicDecrement(var) \

  (__sync_add_and_fetch((int volatile *)(var), -1))

# define atomicCompareAndSwap(var,ov,nv) \

  (__sync_val_compare_and_swap((int volatile*)(var),(int)(ov),(int)(nv)))

# if defined(__i386__) || defined(__x86_64__) || defined(__amd64__)

#  define atomicExchange(var,nv) \

   (__sync_lock_test_and_set((int volatile*)(var),(int)(nv)))

#  define atomicExchangePointer(var,nv) \

   (__sync_lock_test_and_set((void* volatile*)(var),(void*)(nv)))

# else

  static inline int atomicExchange(int volatile *var, int nv) {

    int ov; do { ov = *var;  /* overkill */

    } while (! __sync_bool_compare_and_swap(var, ov, nv));

    return ov;

  }

  static inline void* atomicExchangePointer(void* volatile *var, void* nv) {

    void *ov; do { ov = *var;  /* overkill */

    } while (! __sync_bool_compare_and_swap(var, ov, nv));

    return ov;

  }

# endif

#endif

#if !defined(ATOMIC_MACROS) && defined(__GNUC__)

# if defined(__i386__) || defined(__amd64__) || defined(__x86_64__)

#  define ATOMIC_MACROS "GNU86"

  static inline int atomicIncrement(int volatile *var) {

    int ov; __asm__ __volatile__ ("lock; xaddl %0, %1" 

          : "=r" (ov), "=m" (*var) : "0" (1), "m" (*var) : "cc" );

    return ov + 1;

  }

  static inline int atomicDecrement(int volatile *var) {

    int ov; __asm__ __volatile__ ("lock; xaddl %0, %1" 

         : "=r" (ov), "=m" (*var) : "0" (-1), "m" (*var) : "cc" );

    return ov - 1;

  }

  static inline int atomicExchange(int volatile *var, int nv) {

    int ov; __asm__ __volatile__ ("xchgl %0, %1"

        : "=r" (ov), "=m" (*var) : "0" (nv), "m" (*var)); 

    return ov; 

  }

  static inline int atomicCompareAndSwap(int volatile *var, int ov, int nv) {

    int rv; __asm __volatile ("lock; cmpxchgl %2, %1"

        : "=a" (rv), "=m" (*var) : "r" (nv), "0" (ov), "m" (*var) : "cc");

    return rv;

  }

  static inline void *atomicExchangePointer(void * volatile *var, void *nv) {

    void *ov;  __asm__ __volatile__ (

#  if defined(__x86_64__) || defined(__amd64__)

         "xchgq %0, %1"

#  else

         "xchgl %0, %1"

#  endif

         : "=r" (ov), "=m" (*var) : "0" (nv), "m" (*var)); 

    return ov; 

  }

# endif

#endif

#ifndef ATOMIC_MACROS

  /* emulation */

  extern int atomicIncrement(int volatile *var);

  extern int atomicDecrement(int volatile *var);

  extern int atomicCompareAndSwap(int volatile *var, int ov, int nv);

  extern int atomicExchange(int volatile *var, int nv);

  extern void* atomicExchangePointer(void* volatile *var, void* nv);

#endif

# ifdef __cplusplus

}

# endif

#endif