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/* Implementation of W32-specific threads compatibility routines for

   libgcc2.  */

/* Copyright (C) 1999, 2000, 2002, 2004 Free Software Foundation, Inc.

   Contributed by Mumit Khan <khan@xraylith.wisc.edu>.

   Modified and moved to separate file by Danny Smith

   <dannysmith@users.sourceforge.net>.

This file is part of GCC.

GCC 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 2, or (at your option) any later

version.

GCC 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 GCC; see the file COPYING.  If not, write to the Free

Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.  */

/* As a special exception, if you link this library with other files,

   some of which are compiled with GCC, to produce an executable,

   this library 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.  */

#include <windows.h>

#ifndef __GTHREAD_HIDE_WIN32API

# define __GTHREAD_HIDE_WIN32API 1

#endif

#undef  __GTHREAD_I486_INLINE_LOCK_PRIMITIVES

#define __GTHREAD_I486_INLINE_LOCK_PRIMITIVES

#include <gthr-win32.h>

/* Windows32 threads specific definitions. The windows32 threading model

   does not map well into pthread-inspired gcc's threading model, and so

   there are caveats one needs to be aware of.

   1. The destructor supplied to __gthread_key_create is ignored for

      generic x86-win32 ports. This will certainly cause memory leaks

      due to unreclaimed eh contexts (sizeof (eh_context) is at least

      24 bytes for x86 currently).

      This memory leak may be significant for long-running applications

      that make heavy use of C++ EH.

      However, Mingw runtime (version 0.3 or newer) provides a mechanism

      to emulate pthreads key dtors; the runtime provides a special DLL,

      linked in if -mthreads option is specified, that runs the dtors in

      the reverse order of registration when each thread exits. If

      -mthreads option is not given, a stub is linked in instead of the

      DLL, which results in memory leak. Other x86-win32 ports can use

      the same technique of course to avoid the leak.

   2. The error codes returned are non-POSIX like, and cast into ints.

      This may cause incorrect error return due to truncation values on

      hw where sizeof (DWORD) > sizeof (int).

   3. We are currently using a special mutex instead of the Critical

      Sections, since Win9x does not support TryEnterCriticalSection

      (while NT does).

   The basic framework should work well enough. In the long term, GCC

   needs to use Structured Exception Handling on Windows32.  */

int

__gthr_win32_once (__gthread_once_t *once, void (*func) (void))

{

  if (once == NULL || func == NULL)

    return EINVAL;

  if (! once->done)

    {

      if (InterlockedIncrement (&(once->started)) == 0)

        {

          (*func) ();

          once->done = TRUE;

        }

      else

        {

          /* Another thread is currently executing the code, so wait for it

             to finish; yield the CPU in the meantime.  If performance

             does become an issue, the solution is to use an Event that

             we wait on here (and set above), but that implies a place to

             create the event before this routine is called.  */

          while (! once->done)

            Sleep (0);

        }

    }

  return 0;

}

/* Windows32 thread local keys don't support destructors; this leads to

   leaks, especially in threaded applications making extensive use of

   C++ EH. Mingw uses a thread-support DLL to work-around this problem.  */

int

__gthr_win32_key_create (__gthread_key_t *key, void (*dtor) (void *))

{

  int status = 0;

  DWORD tls_index = TlsAlloc ();

  if (tls_index != 0xFFFFFFFF)

    {

      *key = tls_index;

#ifdef MINGW32_SUPPORTS_MT_EH

      /* Mingw runtime will run the dtors in reverse order for each thread

         when the thread exits.  */

      status = __mingwthr_key_dtor (*key, dtor);

#endif

    }

  else

    status = (int) GetLastError ();

  return status;

}

int

__gthr_win32_key_delete (__gthread_key_t key)

{

  return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();

}

void *

__gthr_win32_getspecific (__gthread_key_t key)

{

  DWORD lasterror;

  void *ptr;

  lasterror = GetLastError();

  ptr = TlsGetValue(key);

  SetLastError( lasterror );

  return ptr;

}

int

__gthr_win32_setspecific (__gthread_key_t key, const void *ptr)

{

  return (TlsSetValue (key, (void*) ptr) != 0) ? 0 : (int) GetLastError ();

}

void

__gthr_win32_mutex_init_function (__gthread_mutex_t *mutex)

{

  mutex->counter = -1;

  mutex->sema = CreateSemaphore (NULL, 0, 65535, NULL);

}

int

__gthr_win32_mutex_lock (__gthread_mutex_t *mutex)

{

  if (InterlockedIncrement (&mutex->counter) == 0 ||

      WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)

    return 0;

  else

    {

      /* WaitForSingleObject returns WAIT_FAILED, and we can only do

         some best-effort cleanup here.  */

      InterlockedDecrement (&mutex->counter);

      return 1;

    }

}

int

__gthr_win32_mutex_trylock (__gthread_mutex_t *mutex)

{

  if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)

    return 0;

  else

    return 1;

}

int

__gthr_win32_mutex_unlock (__gthread_mutex_t *mutex)

{

  if (InterlockedDecrement (&mutex->counter) >= 0)

    return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;

  else

    return 0;

}

void

__gthr_win32_recursive_mutex_init_function (__gthread_recursive_mutex_t *mutex)

{

  mutex->counter = -1;

  mutex->depth = 0;

  mutex->owner = 0;

  mutex->sema = CreateSemaphore (NULL, 0, 65535, NULL);

}

int

__gthr_win32_recursive_mutex_lock (__gthread_recursive_mutex_t *mutex)

{

  DWORD me = GetCurrentThreadId();

  if (InterlockedIncrement (&mutex->counter) == 0)

    {

      mutex->depth = 1;

      mutex->owner = me;

    }

  else if (mutex->owner == me)

    {

      InterlockedDecrement (&mutex->counter);

      ++(mutex->depth);

    }

  else if (WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)

    {

      mutex->depth = 1;

      mutex->owner = me;

    }

  else

    {

      /* WaitForSingleObject returns WAIT_FAILED, and we can only do

         some best-effort cleanup here.  */

      InterlockedDecrement (&mutex->counter);

      return 1;

    }

  return 0;

}

int

__gthr_win32_recursive_mutex_trylock (__gthread_recursive_mutex_t *mutex)

{

  DWORD me = GetCurrentThreadId();

  if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)

    {

      mutex->depth = 1;

      mutex->owner = me;

    }

  else if (mutex->owner == me)

    ++(mutex->depth);

  else

    return 1;

  return 0;

}

int

__gthr_win32_recursive_mutex_unlock (__gthread_recursive_mutex_t *mutex)

{

  --(mutex->depth);

  if (mutex->depth == 0)

    {

      mutex->owner = 0;

      if (InterlockedDecrement (&mutex->counter) >= 0)

        return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;

    }

  return 0;

}