1 files changed, 84 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/nios2/nios2_iss/shmsupp/lock.c b/c/src/lib/libbsp/nios2/nios2_iss/shmsupp/lock.c
new file mode 100644
index 0000000000..c0d29adf00
--- /dev/null
+++ b/c/src/lib/libbsp/nios2/nios2_iss/shmsupp/lock.c
@@ -0,0 +1,84 @@
+/*  Shared Memory Lock Routines
+ *
+ *  This shared memory locked queue support routine need to be
+ *  able to lock the specified locked queue.  Interrupts are
+ *  disabled while the queue is locked to prevent preemption
+ *  and deadlock when two tasks poll for the same lock.
+ *  previous level.
+ *
+ *  COPYRIGHT (c) 1989-1999.
+ *  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.
+ *
+ *  $Id$
+ */
+
+#include <rtems.h>
+#include <bsp.h>
+#include <shm_driver.h>
+
+/*
+ *  Shm_Initialize_lock
+ *
+ *  Initialize the lock for the specified locked queue.
+ */
+
+void Shm_Initialize_lock(
+  Shm_Locked_queue_Control *lq_cb
+)
+{
+  lq_cb->lock = LQ_UNLOCKED;
+}
+
+/*  void _Shm_Lock( &lq_cb )
+ *
+ *  This shared memory locked queue support routine locks the
+ *  specified locked queue.  It disables interrupts to prevent
+ *  a deadlock condition.
+ */
+
+void Shm_Lock(
+  Shm_Locked_queue_Control *lq_cb
+)
+{
+  uint32_t         isr_level;
+  uint32_t         *lockptr = (uint32_t*) &lq_cb->lock;
+  uint32_t         lock_value;
+
+  lock_value = 0x80000000;
+  rtems_interrupt_disable( isr_level );
+
+    Shm_isrstat = isr_level;
+    while ( lock_value ) {
+      asm volatile( ""
+                         : "=r" (lockptr), "=r" (lock_value)
+                         : "0" (lockptr),  "1" (lock_value)
+                  );
+      /*
+       *  If not available, then may want to delay to reduce load on lock.
+       */
+
+      if ( lock_value )
+        rtems_bsp_delay( 10 );   /* approximately 10 microseconds */
+   }
+}
+
+/*
+ *  Shm_Unlock
+ *
+ *  Unlock the lock for the specified locked queue.
+ */
+
+void Shm_Unlock(
+  Shm_Locked_queue_Control *lq_cb
+)
+{
+  uint32_t         isr_level;
+
+  lq_cb->lock = SHM_UNLOCK_VALUE;
+  isr_level = Shm_isrstat;
+  rtems_interrupt_enable( isr_level );
+}