x86-win32 threading support

[Mumit Khan <khan at xraylith dot wisc dot EDU>]

The following adds threading support for x86-win32. This is currently
usable for x86-mingw32* and x86-win32 targets. Cygwin, when it becomes
thread-safe, will use pthreads, not win32 threads. UWIN runtime will
however use this one once it becomes thread-safe. 

Using the resulting runtime, pthreads-win32 passes all tests for
mingw.

See comments in file for caveats, especially the memory leak. When
Cygwin becomes thread-safe, this won't be a problem thanks to dtor
handling in pthreads.

Tue Aug 17 21:36:08 1999  Mumit Khan  <khan@xraylith.wisc.edu>

	* gthr-win32.h: New file.

Index: gthr-win32.h
===================================================================
RCS file: gthr-win32.h
diff -N gthr-win32.h
--- /dev/null	Tue May  5 15:32:27 1998
+++ gthr-win32.h	Tue Aug 17 22:21:35 1999
@@ -0,0 +1,195 @@
+/* Threads compatibily routines for libgcc2.  */
+/* Compile this one with gcc.  */
+/* Copyright (C) 1999 Free Software Foundation, Inc.
+   Contributed by Mumit Khan <khan@xraylith.wisc.edu>.
+
+This file is part of GNU CC.
+
+GNU CC 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.
+
+GNU CC 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 GNU CC; see the file COPYING.  If not, write to
+the Free Software Foundation, 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, 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.  */
+
+#ifndef __gthr_win32_h
+#define __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. 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.
+
+   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).
+  
+   The basic framework should work well enough. */
+
+#define __GTHREADS 1
+
+#include <windows.h>
+#include <errno.h>
+
+typedef DWORD __gthread_key_t;
+
+typedef struct {
+  int done;
+  long started;
+} __gthread_once_t;
+
+typedef HANDLE __gthread_mutex_t;
+
+#define __GTHREAD_ONCE_INIT {FALSE, -1}
+#define __GTHREAD_MUTEX_INIT_FUNCTION __gthread_mutex_init_function
+
+static inline int
+__gthread_active_p ()
+{
+  return 1;
+}
+
+static inline int
+__gthread_once (__gthread_once_t *once, void (*func) ())
+{
+  if (! __gthread_active_p ())
+    return -1;
+  else 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.  */ 
+      while (! once->done)
+        Sleep (0);
+    }
+  
+  return 0;
+}
+
+/* Windows32 thread local keys don't support destructors; to avoid leaks,
+   we will have to figure something out in the future.  */
+static inline int
+__gthread_key_create (__gthread_key_t *key, 
+                      void (*dtor) (void *) __attribute__((__unused__)))
+{
+  int status = 0;
+  DWORD tls_index = TlsAlloc ();
+  if (tls_index != 0xFFFFFFFF)
+    *key = tls_index;
+  else
+    status = (int) GetLastError ();
+  return status;
+}
+
+/* Currently, this routine is never called since win32 keys don't support
+   destructors. Hopefully we'll find a way in the future.  */
+static inline int
+__gthread_key_dtor (__gthread_key_t key, void *ptr)
+{
+  int status = 0;
+
+  /* Just reset the key value to zero. */
+  if (ptr)
+    status = (TlsSetValue (key, 0) != 0) ? 0 : (int) GetLastError ();
+  return status;
+}
+
+/* Currently, this routine is never called since win32 keys don't support
+   destructors. Hopefully we'll find a way in the future.  */
+static inline int
+__gthread_key_delete (__gthread_key_t key)
+{
+  return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
+}
+
+static inline void *
+__gthread_getspecific (__gthread_key_t key)
+{
+  return TlsGetValue (key);
+}
+
+static inline int
+__gthread_setspecific (__gthread_key_t key, const void *ptr)
+{
+  return (TlsSetValue (key, ptr) != 0) ? 0 : (int) GetLastError ();
+}
+
+static inline void
+__gthread_mutex_init_function (__gthread_mutex_t *mutex)
+{
+  /* Create unnamed mutex with default security attr and no initial owner.  */ 
+  *mutex = CreateMutex (NULL, 0, NULL);
+}
+
+static inline int
+__gthread_mutex_lock (__gthread_mutex_t *mutex)
+{
+  int status = 0;
+
+  if (__gthread_active_p ())
+    {
+      if (WaitForSingleObject (*mutex, INFINITE) == WAIT_OBJECT_0)
+	status = 0;
+      else
+	status = 1;
+    }
+  return status;
+}
+
+static inline int
+__gthread_mutex_trylock (__gthread_mutex_t *mutex)
+{
+  int status = 0;
+
+  if (__gthread_active_p ())
+    {
+      if (WaitForSingleObject (*mutex, 0) == WAIT_OBJECT_0)
+	status = 0;
+      else
+	status = 1;
+    }
+  return status;
+}
+
+static inline int
+__gthread_mutex_unlock (__gthread_mutex_t *mutex)
+{
+  if (__gthread_active_p ())
+    return (ReleaseMutex (*mutex) != 0) ? 0 : 1;
+  else
+    return 0;
+}
+
+#endif /* not __gthr_win32_h */
+

Regards,
Mumit