#ifndef MY_ATOMIC_INCLUDED
#define MY_ATOMIC_INCLUDED

/* Copyright (c) 2006, 2016, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   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, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/*
  This header defines five atomic operations:

  my_atomic_add#(&var, what)
    'Fetch and Add'
    add 'what' to *var, and return the old value of *var

  my_atomic_fas#(&var, what)
    'Fetch And Store'
    store 'what' in *var, and return the old value of *var

  my_atomic_cas#(&var, &old, new)
    An odd variation of 'Compare And Set/Swap'
    if *var is equal to *old, then store 'new' in *var, and return TRUE
    otherwise store *var in *old, and return FALSE
    Usually, &old should not be accessed if the operation is successful.

  my_atomic_load#(&var)
    return *var

  my_atomic_store#(&var, what)
    store 'what' in *var

  '#' is substituted by a size suffix - 8, 16, 32, 64, or ptr
  (e.g. my_atomic_add8, my_atomic_fas32, my_atomic_casptr).

  NOTE This operations are not always atomic, so they always must be
  enclosed in my_atomic_rwlock_rdlock(lock)/my_atomic_rwlock_rdunlock(lock)
  or my_atomic_rwlock_wrlock(lock)/my_atomic_rwlock_wrunlock(lock).
  Hint: if a code block makes intensive use of atomic ops, it make sense
  to take/release rwlock once for the whole block, not for every statement.

  On architectures where these operations are really atomic, rwlocks will
  be optimized away.
  8- and 16-bit atomics aren't implemented for windows (see generic-msvc.h),
  but can be added, if necessary. 
*/

#ifndef my_atomic_rwlock_init

#define intptr         void *
/**
  Currently we don't support 8-bit and 16-bit operations.
  It can be added later if needed.
*/
#undef MY_ATOMIC_HAS_8_16

#ifndef MY_ATOMIC_MODE_RWLOCKS
/*
 * Attempt to do atomic ops without locks
 */
#include "atomic/nolock.h"
#endif

#ifndef make_atomic_cas_body
/* nolock.h was not able to generate even a CAS function, fall back */
#include "atomic/rwlock.h"
#endif

/* define missing functions by using the already generated ones */
#ifndef make_atomic_add_body
#define make_atomic_add_body(S)                                 \
  int ## S tmp=*a;                                              \
  while (!my_atomic_cas ## S(a, &tmp, tmp+v)) ;                 \
  v=tmp;
#endif
#ifndef make_atomic_fas_body
#define make_atomic_fas_body(S)                                 \
  int ## S tmp=*a;                                              \
  while (!my_atomic_cas ## S(a, &tmp, v)) ;                     \
  v=tmp;
#endif
#ifndef make_atomic_load_body
#define make_atomic_load_body(S)                                \
  ret= 0; /* avoid compiler warning */                          \
  (void)(my_atomic_cas ## S(a, &ret, ret));
#endif
#ifndef make_atomic_store_body
#define make_atomic_store_body(S)                               \
  (void)(my_atomic_fas ## S (a, v));
#endif

/*
  transparent_union doesn't work in g++
  Bug ?

  Darwin's gcc doesn't want to put pointers in a transparent_union
  when built with -arch ppc64. Complains:
  warning: 'transparent_union' attribute ignored
*/
#if defined(__GNUC__) && !defined(__cplusplus) && \
      ! (defined(__APPLE__) && (defined(_ARCH_PPC64) ||defined (_ARCH_PPC)))
/*
  we want to be able to use my_atomic_xxx functions with
  both signed and unsigned integers. But gcc will issue a warning
  "passing arg N of `my_atomic_XXX' as [un]signed due to prototype"
  if the signedness of the argument doesn't match the prototype, or
  "pointer targets in passing argument N of my_atomic_XXX differ in signedness"
  if int* is used where uint* is expected (or vice versa).
  Let's shut these warnings up
*/
#define make_transparent_unions(S)                              \
        typedef union {                                         \
          int  ## S  i;                                         \
          uint ## S  u;                                         \
        } U_ ## S   MY_ATTRIBUTE ((transparent_union));        \
        typedef union {                                         \
          int  ## S volatile *i;                                \
          uint ## S volatile *u;                                \
        } Uv_ ## S   MY_ATTRIBUTE ((transparent_union));
#define uintptr intptr
make_transparent_unions(8)
make_transparent_unions(16)
make_transparent_unions(32)
make_transparent_unions(64)
make_transparent_unions(ptr)
#undef uintptr
#undef make_transparent_unions
#define a       U_a.i
#define cmp     U_cmp.i
#define v       U_v.i
#define set     U_set.i
#else
#define U_8    int8
#define U_16   int16
#define U_32   int32
#define U_64   int64
#define U_ptr  intptr
#define Uv_8   int8
#define Uv_16  int16
#define Uv_32  int32
#define Uv_64  int64
#define Uv_ptr intptr
#define U_a    volatile *a
#define U_cmp  *cmp
#define U_v    v
#define U_set  set
#endif /* __GCC__ transparent_union magic */

#define make_atomic_cas(S)                                      \
static inline int my_atomic_cas ## S(Uv_ ## S U_a,              \
                            Uv_ ## S U_cmp, U_ ## S U_set)      \
{                                                               \
  int8 ret;                                                     \
  make_atomic_cas_body(S);                                      \
  return ret;                                                   \
}

#define make_atomic_add(S)                                      \
static inline int ## S my_atomic_add ## S(                      \
                        Uv_ ## S U_a, U_ ## S U_v)              \
{                                                               \
  make_atomic_add_body(S);                                      \
  return v;                                                     \
}

#define make_atomic_fas(S)                                      \
static inline int ## S my_atomic_fas ## S(                      \
                         Uv_ ## S U_a, U_ ## S U_v)             \
{                                                               \
  make_atomic_fas_body(S);                                      \
  return v;                                                     \
}

#define make_atomic_load(S)                                     \
static inline int ## S my_atomic_load ## S(Uv_ ## S U_a)        \
{                                                               \
  int ## S ret;                                                 \
  make_atomic_load_body(S);                                     \
  return ret;                                                   \
}

#define make_atomic_store(S)                                    \
static inline void my_atomic_store ## S(                        \
                     Uv_ ## S U_a, U_ ## S U_v)                 \
{                                                               \
  make_atomic_store_body(S);                                    \
}

#ifdef MY_ATOMIC_HAS_8_16
make_atomic_cas(8)
make_atomic_cas(16)
#endif
make_atomic_cas(32)
make_atomic_cas(64)
make_atomic_cas(ptr)

#ifdef MY_ATOMIC_HAS_8_16
make_atomic_add(8)
make_atomic_add(16)
#endif
make_atomic_add(32)
make_atomic_add(64)

#ifdef MY_ATOMIC_HAS_8_16
make_atomic_load(8)
make_atomic_load(16)
#endif
make_atomic_load(32)
make_atomic_load(64)
make_atomic_load(ptr)

#ifdef MY_ATOMIC_HAS_8_16
make_atomic_fas(8)
make_atomic_fas(16)
#endif
make_atomic_fas(32)
make_atomic_fas(64)
make_atomic_fas(ptr)

#ifdef MY_ATOMIC_HAS_8_16
make_atomic_store(8)
make_atomic_store(16)
#endif
make_atomic_store(32)
make_atomic_store(64)
make_atomic_store(ptr)

#ifdef _atomic_h_cleanup_
#include _atomic_h_cleanup_
#undef _atomic_h_cleanup_
#endif

#undef U_8
#undef U_16
#undef U_32
#undef U_64
#undef U_ptr
#undef Uv_8
#undef Uv_16
#undef Uv_32
#undef Uv_64
#undef Uv_ptr
#undef a
#undef cmp
#undef v
#undef set
#undef U_a
#undef U_cmp
#undef U_v
#undef U_set
#undef make_atomic_add
#undef make_atomic_cas
#undef make_atomic_load
#undef make_atomic_store
#undef make_atomic_fas
#undef make_atomic_add_body
#undef make_atomic_cas_body
#undef make_atomic_load_body
#undef make_atomic_store_body
#undef make_atomic_fas_body
#undef intptr

/*
  the macro below defines (as an expression) the code that
  will be run in spin-loops. Intel manuals recummend to have PAUSE there.
  It is expected to be defined in include/atomic/ *.h files
*/
#ifndef LF_BACKOFF
#define LF_BACKOFF (1)
#endif

#define MY_ATOMIC_OK       0
#define MY_ATOMIC_NOT_1CPU 1
C_MODE_START
extern int my_atomic_initialize();
C_MODE_END

#endif

#endif /* MY_ATOMIC_INCLUDED */
