* mutex.c (pthread_mutex_trylock): use

        ptw32_interlocked_compare_exchange function pointer
        rather than ptw32_InterlockedCompareExchange() directly
        to retain portability to non-iX86 processors,
        e.g. WinCE etc. The pointer will point to the native
        OS version of InterlockedCompareExchange() if the
        OS supports it (see ChangeLog entry of 2001-10-17).

4 files changed, 61 insertions, 43 deletions

diff --git a/ChangeLog b/ChangeLog
index 72593f2..a3e1403 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2002-01-08  Ross Johnson  <rpj@setup1.ise.canberra.edu.au>
+
+	* mutex.c (pthread_mutex_trylock): use
+	ptw32_interlocked_compare_exchange function pointer
+	rather than ptw32_InterlockedCompareExchange() directly
+	to retain portability to non-iX86 processors,
+	e.g. WinCE etc. The pointer will point to the native
+	OS version of InterlockedCompareExchange() if the
+	OS supports it (see ChangeLog entry of 2001-10-17).
+
 2002-01-07  Ross Johnson  <rpj@setup1.ise.canberra.edu.au>
 
 	Contributed by - Thomas Pfaff <tpfaff@gmx.net>
@@ -7,12 +17,13 @@
 	section calls.
 	(pthread_mutex_destroy): Likewise.
 	(pthread_mutex_unlock): Likewise.
-	(pthread_mutex_trylock): Likewise; recursive mutexes
-	now increment the lock count rather than return EBUSY;
-	errorcheck mutexes return EDEADLCK rather than
-	EBUSY. This behaviour is consistent with the Solaris
-	pthreads implementation.
-
+	(pthread_mutex_trylock): Likewise; uses
+	ptw32_InterlockedCompareExchange() to avoid need for
+	critical section; library is no longer i386 compatible;
+	recursive mutexes now increment the lock count rather
+	than return EBUSY; errorcheck mutexes return EDEADLCK
+	rather than EBUSY. This behaviour is consistent with the
+	Solaris pthreads implementation.
 	* implement.h (pthread_mutex_t_): Remove critical
 	section element - no longer needed.
 	
diff --git a/implement.h b/implement.h
index e07306b..e075ee9 100644
--- a/implement.h
+++ b/implement.h
@@ -156,11 +156,17 @@ struct sem_t_ {
 #define PTW32_OBJECT_INVALID   NULL
 
 struct pthread_mutex_t_ {
-  LONG lock_idx;
-  int recursive_count;
-  int kind;
+  LONG lock_idx;               /* Provides exclusive access to mutex state
+                                  via the Interlocked* mechanism, as well
+                                  as a count of the number of threads
+                                  waiting on the mutex. */
+  int recursive_count;         /* Number of unlocks a thread needs to perform
+                                  before the lock is released (recursive
+                                  mutexes only). */
+  int kind;                    /* Mutex type. */
   pthread_t ownerThread;
-  HANDLE wait_sema;
+  HANDLE wait_sema;            /* Mutex release notification to waiting
+                                  threads. */
 };
 
 struct pthread_mutexattr_t_ {
diff --git a/mutex.c b/mutex.c
index 7a232c5..d1d7aad 100644
--- a/mutex.c
+++ b/mutex.c
@@ -699,12 +699,12 @@ pthread_mutex_unlock(pthread_mutex_t *mutex)
 	    {
 	      mx->ownerThread = NULL;
 	      
-          if( InterlockedDecrement( &mx->lock_idx ) >= 0 )
-          {
-             /* Someone is waiting on that mutex */
-             ReleaseSemaphore( mx->wait_sema, 1, NULL );
-          }
-        }
+              if( InterlockedDecrement( &mx->lock_idx ) >= 0 )
+                {
+                  /* Someone is waiting on that mutex */
+                  ReleaseSemaphore( mx->wait_sema, 1, NULL );
+                }
+            }
 	}
       else
 	{
@@ -745,35 +745,35 @@ pthread_mutex_trylock(pthread_mutex_t *mutex)
 
   if (result == 0)
     {
-
-      if( PTW32_MUTEX_LOCK_IDX_INIT == ptw32_InterlockedCompareExchange(
-             &mx->lock_idx, 0, PTW32_MUTEX_LOCK_IDX_INIT ) )
-      {
-         mx->recursive_count = 1;
-         mx->ownerThread = (mx->kind != PTHREAD_MUTEX_FAST_NP
-                            ? pthread_self()
-                            : (pthread_t) PTW32_MUTEX_OWNER_ANONYMOUS);
-      }
-
+      if ( (PTW32_INTERLOCKED_LONG) PTW32_MUTEX_LOCK_IDX_INIT ==
+           ptw32_interlocked_compare_exchange((PTW32_INTERLOCKED_LPLONG) &mx->lock_idx,
+                                              (PTW32_INTERLOCKED_LONG) 0,
+                                              (PTW32_INTERLOCKED_LONG) PTW32_MUTEX_LOCK_IDX_INIT))
+        {
+          mx->recursive_count = 1;
+          mx->ownerThread = (mx->kind != PTHREAD_MUTEX_FAST_NP
+                             ? pthread_self()
+                             : (pthread_t) PTW32_MUTEX_OWNER_ANONYMOUS);
+        }
       else
-      {
-         if( mx->kind != PTHREAD_MUTEX_FAST_NP &&
-             pthread_equal( mx->ownerThread, pthread_self() ) )
-         {
-            if( mx->kind == PTHREAD_MUTEX_RECURSIVE_NP )
+        {
+          if( mx->kind != PTHREAD_MUTEX_FAST_NP &&
+              pthread_equal( mx->ownerThread, pthread_self() ) )
             {
-               mx->recursive_count++;
+              if( mx->kind == PTHREAD_MUTEX_RECURSIVE_NP )
+                {
+                  mx->recursive_count++;
+                }
+              else
+                {
+                  result = EDEADLK;
+                }
             }
-            else
+          else
             {
-               result = EDEADLK;
+              result = EBUSY;
             }
-         }
-         else
-         {
-            result = EBUSY;
-         }
-      }
+        }
     }
 
   return(result);
diff --git a/private.c b/private.c
index 8aa7d84..0d6b5f3 100644
--- a/private.c
+++ b/private.c
@@ -1080,9 +1080,10 @@ ptw32_InterlockedCompareExchange(PTW32_INTERLOCKED_LPLONG location,
 #else
 
   /*
-   * If we get to here then we should be running on a Win95 system but either
-   * running on something other than an X86 processor, or a compiler other
-   * than MSVC or GCC. Pthreads-win32 doesn't support that platform (yet).
+   * If execution gets to here then we should be running on a Win95 system
+   * but either running on something other than an X86 processor, or a
+   * compiler other than MSVC or GCC. Pthreads-win32 doesn't support that
+   * platform (yet).
    */
 
   result = 0;