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+/*
+ * 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));
+ }
+}