moved ringbuf.h to a shared include directory

c/src/exec/libcsupport/include/ringbuf.h

@@ -0,0 +1,42 @@
+/*
+ *  ringbuf.h 
+ *
+ *  This file provides simple ring buffer functionality.
+ *
+ *  $Id$
+ */
+
+#ifndef __RINGBUF_H__
+#define __RINGBUF_H__
+
+#ifndef RINGBUF_QUEUE_LENGTH
+#define RINGBUF_QUEUE_LENGTH 200
+#endif
+
+typedef struct {
+  char buffer[RINGBUF_QUEUE_LENGTH];
+  int  head;
+  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_Add_character( _buffer, _ch ) \
+  do { \
+    (_buffer)->buffer[ (_buffer)->tail ] = (_ch); \
+    (_buffer)->tail = ((_buffer)->tail+1) % RINGBUF_QUEUE_LENGTH; \
+  } while ( 0 ) 
+
+#define Ring_buffer_Remove_character( _buffer, _ch ) \
+  do { \
+    (_ch) = (_buffer)->buffer[ (_buffer)->head ]; \
+    (_buffer)->head = ((_buffer)->head+1) % RINGBUF_QUEUE_LENGTH; \
+  } while ( 0 ) 
+
+#endif