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/*

 *  ringbuf.h

 *

 *  This file provides simple ring buffer functionality.

 *

 *  $Id: ringbuf.h,v 1.2 2001-09-27 11:59:35 chris Exp $

 */

#ifndef __RINGBUF_H__

#define __RINGBUF_H__

#ifndef RINGBUF_QUEUE_LENGTH

#define RINGBUF_QUEUE_LENGTH 128

#endif

typedef struct {

  char 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 { \

    rtems_unsigned32 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 { \

    rtems_unsigned32 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