1 files changed, 55 insertions, 0 deletions
diff --git a/cpukit/libcsupport/include/ringbuf.h b/cpukit/libcsupport/include/ringbuf.h
new file mode 100644
index 0000000000..39941d857d
--- /dev/null
+++ b/cpukit/libcsupport/include/ringbuf.h
@@ -0,0 +1,55 @@
+/**
+ *  @file rtems/ringbuf.h
+ *
+ *  This file provides simple ring buffer functionality.
+ */
+
+/*
+ *  $Id$
+ */
+
+#ifndef _RTEMS_RINGBUF_H
+#define _RTEMS_RINGBUF_H
+
+#ifndef RINGBUF_QUEUE_LENGTH
+#define RINGBUF_QUEUE_LENGTH 128
+#endif
+
+typedef struct {
+  uint8_t buffer[RINGBUF_QUEUE_LENGTH];
+  volatile int  head;
+  volatile int  tail;
+} Ring_buffer_t;
+
+#define Ring_buffer_Initialize( _buffer ) \
+  do { \
+    (_buffer)->head = (_buffer)->tail = 0; \
+  } while ( 0 )
+
+#define Ring_buffer_Is_empty( _buffer ) \
+   ( (_buffer)->head == (_buffer)->tail )
+
+#define Ring_buffer_Is_full( _buffer ) \
+   ( (_buffer)->head == ((_buffer)->tail + 1) % RINGBUF_QUEUE_LENGTH )
+
+#define Ring_buffer_Add_character( _buffer, _ch ) \
+  do { \
+    uint32_t   isrlevel; \
+    \
+    rtems_interrupt_disable( isrlevel ); \
+      (_buffer)->tail = ((_buffer)->tail+1) % RINGBUF_QUEUE_LENGTH; \
+      (_buffer)->buffer[ (_buffer)->tail ] = (_ch); \
+    rtems_interrupt_enable( isrlevel ); \
+  } while ( 0 )
+
+#define Ring_buffer_Remove_character( _buffer, _ch ) \
+  do { \
+    uint32_t   isrlevel; \
+    \
+    rtems_interrupt_disable( isrlevel ); \
+      (_buffer)->head = ((_buffer)->head+1) % RINGBUF_QUEUE_LENGTH; \
+      (_ch) = (_buffer)->buffer[ (_buffer)->head ]; \
+    rtems_interrupt_enable( isrlevel ); \
+  } while ( 0 )
+
+#endif