/*
    Copyright 2005-2015 Intel Corporation.  All Rights Reserved.

    This file is part of Threading Building Blocks. Threading Building Blocks is free software;
    you can redistribute it and/or modify it under the terms of the GNU General Public License
    version 2  as  published  by  the  Free Software Foundation.  Threading Building Blocks 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 Threading Building Blocks; if not, write to the
    Free Software Foundation, Inc.,  51 Franklin St,  Fifth Floor,  Boston,  MA 02110-1301 USA

    As a special exception,  you may use this file  as part of a free software library without
    restriction.  Specifically,  if other files instantiate templates  or use macros or inline
    functions from this file, or you compile this file and link it with other files to produce
    an executable,  this file does not by itself cause the resulting executable to be covered
    by the GNU General Public License. This exception does not however invalidate any other
    reasons why the executable file might be covered by the GNU General Public License.
*/

/* The API to enable interoperability between Intel(R) Cilk(TM) Plus and 
   Intel(R) Threading Building Blocks. */

#ifndef CILK_TBB_INTEROP_H
#define CILK_TBB_INTEROP_H

#ifndef _WIN32
#ifdef IN_CILK_RUNTIME
#define CILK_EXPORT __attribute__((visibility("protected")))
#else
#define CILK_EXPORT /* nothing */
#endif
#else
#ifdef IN_CILK_RUNTIME
#define CILK_EXPORT __declspec(dllexport)
#else
#define CILK_EXPORT __declspec(dllimport)
#endif  // IN_CILK_RUNTIME
#endif // _WIN32

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/* A return code.  0 indicates success */
typedef int __cilk_tbb_retcode;

enum __cilk_tbb_stack_op {
    CILK_TBB_STACK_ORPHAN, // disconnecting stack from a thread
    CILK_TBB_STACK_ADOPT,  // reconnecting orphaned stack to a trhead
    CILK_TBB_STACK_RELEASE // releasing stack
};

typedef __cilk_tbb_retcode (*__cilk_tbb_pfn_stack_op)(enum __cilk_tbb_stack_op, void* data);

typedef __cilk_tbb_retcode (*__cilk_tbb_pfn_unwatch_stacks)(void *data);

/* Each thunk structure has two pointers: "routine" and "data".
   The caller of the thunk invokes *routine, passing "data" as the void* parameter. */

/* Thunk invoked by Intel Cilk Plus runtime (cilkrts) when it changes the relationship
   between a stack and a thread. It does not matter what stack the thunk runs on.
   The thread (not fiber) on which the thunk runs is important.

   CILK_TBB_STACK_ORPHAN
      The thunk must be invoked on the thread disconnecting itself from the stack.
      Must "happen before" the stack is adopted elsewhere.
   CILK_TBB_STACK_ADOPT
      The thunk must be invoked on the thread adopting the stack.
   CILK_TBB_STACK_RELEASE
      The thunk must be invoked on the thread doing the releasing,
      Must "happen before" the stack is used elsewhere.

   When a non-empty stack is transferred between threads, the first thread must orphan it 
   and the second thread must adopt it.

   An empty stack can be transferred similarly, or simply released by the first thread.

   Here is a summary of the actions as transitions on a state machine.

                       watch                                    ORPHAN
                       -->-->                                   -->--
                      /      \                                 /     \
   (freed empty stack)       (TBB sees stack running on thread)      (stack in limbo)
                |     \     /                                  \     /     |
                |      --<--                                    --<--      |
                ^      RELEASE or                              ADOPT       V
                 \     unwatch                                            / 
                  \                                                      /
                   --------------------------<---------------------------
                                          RELEASE
*/
struct __cilk_tbb_stack_op_thunk {
    __cilk_tbb_pfn_stack_op routine;
    void* data;                 /* Set by TBB */
};

/* Thunk invoked by TBB when it is no longer interested in watching the stack bound to the current thread. */
struct __cilk_tbb_unwatch_thunk {
    __cilk_tbb_pfn_unwatch_stacks routine;
    void* data;      
};

/* Defined by cilkrts, called by TBB.
   Requests that cilkrts invoke __cilk_tbb_stack_op_thunk when it orphans a stack. 
   cilkrts sets *u to a thunk that TBB should call when it is no longer interested in watching the stack. */
CILK_EXPORT
__cilk_tbb_retcode __cilkrts_watch_stack(struct __cilk_tbb_unwatch_thunk* u,
                                         struct __cilk_tbb_stack_op_thunk o);

#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif  // CILK_TBB_INTEROP_H
