score: Add self-contained semaphore implementation

4 files changed, 146 insertions, 0 deletions

diff --git a/cpukit/libmisc/monitor/mon-prmisc.c b/cpukit/libmisc/monitor/mon-prmisc.c
index ae7f75d350..4656ed297a 100644
--- a/cpukit/libmisc/monitor/mon-prmisc.c
+++ b/cpukit/libmisc/monitor/mon-prmisc.c
@@ -135,6 +135,7 @@ static const rtems_assoc_t rtems_monitor_state_assoc[] = {
     { "Wsem",   STATES_WAITING_FOR_SEMAPHORE, 0 },
     { "Wsig",   STATES_WAITING_FOR_SIGNAL, 0 },
     { "Wslmtx", STATES_WAITING_FOR_SYS_LOCK_MUTEX, 0 },
+    { "Wslsem", STATES_WAITING_FOR_SYS_LOCK_SEMAPHORE, 0 },
     { "Wsysev", STATES_WAITING_FOR_SYSTEM_EVENT, 0 },
     { "Wterm",  STATES_WAITING_FOR_TERMINATION, 0 },
     { "Wtime",  STATES_WAITING_FOR_TIME, 0 },
diff --git a/cpukit/score/Makefile.am b/cpukit/score/Makefile.am
index c107805a3d..4b4c1f5fce 100644
--- a/cpukit/score/Makefile.am
+++ b/cpukit/score/Makefile.am
@@ -349,6 +349,7 @@ libscore_a_SOURCES += src/profilingisrentryexit.c
 libscore_a_SOURCES += src/mutex.c
 libscore_a_SOURCES += src/once.c
 libscore_a_SOURCES += src/resourceiterate.c
+libscore_a_SOURCES += src/semaphore.c
 libscore_a_SOURCES += src/smpbarrierwait.c
 libscore_a_SOURCES += src/kern_tc.c
 
diff --git a/cpukit/score/include/rtems/score/statesimpl.h b/cpukit/score/include/rtems/score/statesimpl.h
index 4ad8786387..7805ca4c9b 100644
--- a/cpukit/score/include/rtems/score/statesimpl.h
+++ b/cpukit/score/include/rtems/score/statesimpl.h
@@ -88,6 +88,8 @@ extern "C" {
 #define STATES_WAITING_FOR_JOIN                0x1000000
 /** This macro corresponds to a task waiting for a <sys/lock.h> mutex. */
 #define STATES_WAITING_FOR_SYS_LOCK_MUTEX      0x2000000
+/** This macro corresponds to a task waiting for a <sys/lock.h> semaphore. */
+#define STATES_WAITING_FOR_SYS_LOCK_SEMAPHORE  0x4000000
 
 /** This macro corresponds to a task which is in an interruptible
  *  blocking state.
@@ -106,6 +108,7 @@ extern "C" {
                                  STATES_WAITING_FOR_BARRIER            | \
                                  STATES_WAITING_FOR_BSD_WAKEUP         | \
                                  STATES_WAITING_FOR_SYS_LOCK_MUTEX     | \
+                                 STATES_WAITING_FOR_SYS_LOCK_SEMAPHORE | \
                                  STATES_WAITING_FOR_RWLOCK             )
 
 /** This macro corresponds to a task waiting which is blocked. */
diff --git a/cpukit/score/src/semaphore.c b/cpukit/score/src/semaphore.c
new file mode 100644
index 0000000000..94e5209fad
--- /dev/null
+++ b/cpukit/score/src/semaphore.c
@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2015 embedded brains GmbH.  All rights reserved.
+ *
+ *  embedded brains GmbH
+ *  Dornierstr. 4
+ *  82178 Puchheim
+ *  Germany
+ *  <rtems@embedded-brains.de>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/license/LICENSE.
+ */
+
+#if HAVE_CONFIG_H
+  #include "config.h"
+#endif
+
+#if HAVE_STRUCT__THREAD_QUEUE_QUEUE
+
+#include <sys/lock.h>
+
+#include <rtems/score/assert.h>
+#include <rtems/score/threadimpl.h>
+#include <rtems/score/threadqimpl.h>
+
+#define SEMAPHORE_TQ_OPERATIONS &_Thread_queue_Operations_priority
+
+typedef struct {
+  Thread_queue_Syslock_queue Queue;
+  unsigned int count;
+} Semaphore_Control;
+
+RTEMS_STATIC_ASSERT(
+  offsetof( Semaphore_Control, Queue )
+    == offsetof( struct _Semaphore_Control, _Queue ),
+  SEMAPHORE_CONTROL_QUEUE
+);
+
+RTEMS_STATIC_ASSERT(
+  offsetof( Semaphore_Control, count )
+    == offsetof( struct _Semaphore_Control, _count ),
+  SEMAPHORE_CONTROL_COUNT
+);
+
+RTEMS_STATIC_ASSERT(
+  sizeof( Semaphore_Control ) == sizeof( struct _Semaphore_Control ),
+  SEMAPHORE_CONTROL_SIZE
+);
+
+static Semaphore_Control *_Semaphore_Get(
+  struct _Semaphore_Control *_sem
+)
+{
+  return (Semaphore_Control *) _sem;
+}
+
+static Thread_Control *_Semaphore_Queue_acquire(
+  Semaphore_Control *sem,
+  ISR_lock_Context  *lock_context
+)
+{
+  Thread_Control *executing;
+
+  _ISR_lock_ISR_disable( lock_context );
+  executing = _Thread_Executing;
+  _Thread_queue_Queue_acquire_critical(
+    &sem->Queue.Queue,
+    &executing->Potpourri_stats,
+    lock_context
+  );
+
+  return executing;
+}
+
+static void _Semaphore_Queue_release(
+  Semaphore_Control *sem,
+  ISR_lock_Context  *lock_context
+)
+{
+  _Thread_queue_Queue_release( &sem->Queue.Queue, lock_context );
+}
+
+void _Semaphore_Wait( struct _Semaphore_Control *_sem )
+{
+  Semaphore_Control *sem ;
+  ISR_lock_Context   lock_context;
+  Thread_Control    *executing;
+  unsigned int       count;
+
+  sem = _Semaphore_Get( _sem );
+  executing = _Semaphore_Queue_acquire( sem, &lock_context );
+
+  count = sem->count;
+  if ( count > 0 ) {
+    sem->count = count - 1;
+    _Semaphore_Queue_release( sem, &lock_context );
+  } else {
+    _Thread_queue_Enqueue_critical(
+      &sem->Queue.Queue,
+      SEMAPHORE_TQ_OPERATIONS,
+      executing,
+      STATES_WAITING_FOR_SYS_LOCK_SEMAPHORE,
+      0,
+      0,
+      &lock_context
+    );
+  }
+}
+
+void _Semaphore_Post( struct _Semaphore_Control *_sem )
+{
+  Semaphore_Control  *sem;
+  ISR_lock_Context    lock_context;
+  Thread_queue_Heads *heads;
+
+  sem = _Semaphore_Get( _sem );
+  _Semaphore_Queue_acquire( sem, &lock_context );
+
+  heads = sem->Queue.Queue.heads;
+  if ( heads == NULL ) {
+    _Assert( sem->count < UINT_MAX );
+    ++sem->count;
+    _Semaphore_Queue_release( sem, &lock_context );
+  } else {
+    const Thread_queue_Operations *operations;
+    Thread_Control *first;
+
+    operations = SEMAPHORE_TQ_OPERATIONS;
+    first = ( *operations->first )( heads );
+
+    _Thread_queue_Extract_critical(
+      &sem->Queue.Queue,
+      operations,
+      first,
+      &lock_context
+    );
+  }
+}
+
+#endif /* HAVE_STRUCT__THREAD_QUEUE_QUEUE */