From 99e8ecc5759668fd3af379eaddd70b4ae50ecd7f Mon Sep 17 00:00:00 2001
From: rpj <rpj>
Date: Thu, 5 Jul 2001 11:57:32 +0000
Subject: Added new routines from POSIX 1003.1j. This is alpha level code.

        * spin.c: New module implementing spin locks.
        * barrier.c: New module implementing barriers.
        * pthread.h (_POSIX_SPIN_LOCKS): defined.
        (_POSIX_BARRIERS): Defined.
        (pthread_spin_*): Defined.
        (pthread_barrier*): Defined.
        (PTHREAD_BARRIER_SERIAL_THREAD): Defined.
        * implement.h (pthread_spinlock_t_): Defined.
        (pthread_barrier_t_): Defined.
        (pthread_barrierattr_t_): Defined.

        * mutex.c (pthread_mutex_lock): Return with the error
        if an auto-initialiser initialisation fails.

        * nonportable.c (pthread_getprocessors_np): New; gets the
        number of available processors for the current process.
---
 spin.c | 207 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 207 insertions(+)
 create mode 100644 spin.c

(limited to 'spin.c')

diff --git a/spin.c b/spin.c
new file mode 100644
index 0000000..5f30cfc
--- /dev/null
+++ b/spin.c
@@ -0,0 +1,207 @@
+/*
+ * spin.c
+ *
+ * Description:
+ * This translation unit implements spin locks primitives.
+ *
+ * Pthreads-win32 - POSIX Threads Library for Win32
+ * Copyright (C) 1998
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA
+ */
+
+#include "pthread.h"
+#include "implement.h"
+
+/*
+ * This works because the mask that is formed exposes all but the
+ * first two LSBs. If the spinlock is using a mutex rather than
+ * the interlock mechanism then there will always be high bits
+ * to indicate this. This is all just to save the overhead of
+ * using a non-simple struct for spinlocks.
+ */
+#define PTW32_SPIN_SPINS(_lock) \
+  (0 == (_lock->u.mx & (pthread_mutex_t) ~(PTW32_OBJECT_INVALID | PTW32_SPIN_UNLOCK | PTW32_SPIN_LOCKED)))
+
+
+int
+pthread_spin_init(pthread_spinlock_t *lock, int pshared)
+{
+  int CPUs = 1;
+  int result = 0;
+
+  if (lock == NULL)
+    {
+      return EINVAL;
+    }
+
+  (void) pthread_getprocessors_np(&CPUs);
+
+  if (CPUs > 1)
+    {
+      if (pshared == PTHREAD_PROCESS_SHARED)
+        {
+          /*
+           * Creating spinlock that can be shared between
+           * processes.
+           */
+#if _POSIX_THREAD_PROCESS_SHARED
+
+          /*
+           * Not implemented yet.
+           */
+
+#error ERROR [__FILE__, line __LINE__]: Process shared spin locks are not supported yet.
+
+
+#else
+
+          result = ENOSYS;
+          goto FAIL0;
+
+#endif /* _POSIX_THREAD_PROCESS_SHARED */
+
+        }
+
+      lock->u.interlock = PTW32_SPIN_UNLOCKED;
+    }
+  else
+    {
+      pthread_mutexattr_t ma;
+      result = pthread_mutexattr_init(&ma);
+
+      if (0 == result)
+        {
+          ma->pshared = pshared;
+          result = pthread_mutex_init(&(lock->u.mx), &ma);
+        }
+    }
+
+FAIL0:
+
+  return(result);
+}
+
+int
+pthread_spin_destroy(pthread_spinlock_t *lock)
+{
+  if (lock == NULL)
+    {
+      return EINVAL;
+    }
+
+  if (PTW32_SPIN_SPINS(lock))
+    {
+      if ( PTW32_SPIN_UNLOCKED !=
+           InterlockedCompareExchange((LPLONG) &(lock->u.interlock),
+                                      (LPLONG) PTW32_OBJECT_INVALID,
+                                      (LPLONG) PTW32_SPIN_UNLOCKED))
+        {
+          return EINVAL;
+        }
+      else
+        {
+          return 0;
+        }
+    }
+  else
+    {
+      return pthread_mutex_destroy(&(lock->u.mx));
+    }
+}
+
+
+int
+pthread_spin_lock(pthread_spinlock_t *lock)
+{
+  if (lock == NULL)
+    {
+      return EINVAL;
+    }
+
+  if (PTW32_SPIN_SPINS(lock))
+    {
+      while ( PTW32_SPIN_UNLOCKED !=
+              InterlockedCompareExchange((LPLONG) &(lock->u.interlock),
+                                         (LPLONG) PTW32_SPIN_LOCKED,
+                                         (LPLONG) PTW32_SPIN_UNLOCKED) )
+        {
+          /* Spin */
+        }
+    }
+  else
+    {
+      return pthread_mutex_lock(&(lock->u.mx));
+    }
+
+  return 0;
+}
+
+int
+pthread_spin_unlock(pthread_spinlock_t *lock)
+{
+  if (lock == NULL)
+    {
+      return EINVAL;
+    }
+
+  if (PTW32_SPIN_SPINS(lock))
+    {
+      if (PTW32_SPIN_LOCKED !=
+          InterlockedCompareExchange((LPLONG) &(lock->u.interlock),
+                                     (LPLONG) PTW32_SPIN_UNLOCKED,
+                                     (LPLONG) PTW32_SPIN_LOCKED ) )
+        {
+          return 0;
+        }
+      else
+        {
+          return EINVAL;
+        }
+    }
+  else
+    {
+      return pthread_mutex_unlock(&(lock->u.mx));
+    }
+}
+
+int
+pthread_spin_trylock(pthread_spinlock_t *lock)
+{
+  if (lock == NULL)
+    {
+      return EINVAL;
+    }
+
+  if (PTW32_SPIN_SPINS(lock))
+    {
+      if (PTW32_SPIN_UNLOCKED !=
+          InterlockedCompareExchange((LPLONG) &(lock->u.interlock),
+                                     (LPLONG) PTW32_SPIN_LOCKED,
+                                     (LPLONG) PTW32_SPIN_UNLOCKED ) )
+        {
+          return EBUSY;
+        }
+      else
+        {
+          return 0;
+        }
+    }
+  else
+    {
+      return pthread_mutex_trylock(&(lock->u.mx));
+    }
+}
-- 
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