1 files changed, 99 insertions, 0 deletions
diff --git a/cpukit/score/src/threadchangepriority.c b/cpukit/score/src/threadchangepriority.c
new file mode 100644
index 0000000000..95011d8237
--- /dev/null
+++ b/cpukit/score/src/threadchangepriority.c
@@ -0,0 +1,99 @@
+/*
+ *  Thread Handler / Change Priority
+ *
+ *  COPYRIGHT (c) 1989-2011.
+ *  On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/system.h>
+#include <rtems/score/isr.h>
+#include <rtems/score/scheduler.h>
+#include <rtems/score/schedulerpriority.h>
+#include <rtems/score/thread.h>
+#include <rtems/score/threadq.h>
+
+void _Thread_Change_priority(
+  Thread_Control   *the_thread,
+  Priority_Control  new_priority,
+  bool              prepend_it
+)
+{
+  ISR_Level      level;
+  States_Control state, original_state;
+
+  /*
+   * Save original state
+   */
+  original_state = the_thread->current_state;
+
+  /*
+   * Set a transient state for the thread so it is pulled off the Ready chains.
+   * This will prevent it from being scheduled no matter what happens in an
+   * ISR.
+   */
+  _Thread_Set_transient( the_thread );
+
+  /*
+   *  Do not bother recomputing all the priority related information if
+   *  we are not REALLY changing priority.
+   */
+ if ( the_thread->current_priority != new_priority )
+    _Thread_Set_priority( the_thread, new_priority );
+
+  _ISR_Disable( level );
+
+  /*
+   *  If the thread has more than STATES_TRANSIENT set, then it is blocked,
+   *  If it is blocked on a thread queue, then we need to requeue it.
+   */
+  state = the_thread->current_state;
+  if ( state != STATES_TRANSIENT ) {
+    /* Only clear the transient state if it wasn't set already */
+    if ( ! _States_Is_transient( original_state ) )
+      the_thread->current_state = _States_Clear( STATES_TRANSIENT, state );
+    _ISR_Enable( level );
+    if ( _States_Is_waiting_on_thread_queue( state ) ) {
+      _Thread_queue_Requeue( the_thread->Wait.queue, the_thread );
+    }
+    return;
+  }
+
+  /* Only clear the transient state if it wasn't set already */
+  if ( ! _States_Is_transient( original_state ) ) {
+    /*
+     *  Interrupts are STILL disabled.
+     *  We now know the thread will be in the READY state when we remove
+     *  the TRANSIENT state.  So we have to place it on the appropriate
+     *  Ready Queue with interrupts off.
+     */
+    the_thread->current_state = _States_Clear( STATES_TRANSIENT, state );
+
+    if ( prepend_it )
+      _Scheduler_Enqueue_first( the_thread );
+    else
+      _Scheduler_Enqueue( the_thread );
+  }
+
+  _ISR_Flash( level );
+
+  /*
+   *  We altered the set of thread priorities.  So let's figure out
+   *  who is the heir and if we need to switch to them.
+   */
+  _Scheduler_Schedule();
+
+  if ( !_Thread_Is_executing_also_the_heir() &&
+       _Thread_Executing->is_preemptible )
+    _Thread_Dispatch_necessary = true;
+  _ISR_Enable( level );
+}