include/rtems/ringbuf.h

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  * @file
0005  *
0006  * @brief Simple Ring Buffer Functionality
0007  *
0008  * This file provides simple ring buffer functionality.
0009  */
0010
0011 /*
0012  * COPYRIGHT (C) 1989-1999 On-Line Applications Research Corporation (OAR).
0013  *
0014  * Redistribution and use in source and binary forms, with or without
0015  * modification, are permitted provided that the following conditions
0016  * are met:
0017  * 1. Redistributions of source code must retain the above copyright
0018  *    notice, this list of conditions and the following disclaimer.
0019  * 2. Redistributions in binary form must reproduce the above copyright
0020  *    notice, this list of conditions and the following disclaimer in the
0021  *    documentation and/or other materials provided with the distribution.
0022  *
0023  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0024  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0025  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0026  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0027  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0028  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0029  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0030  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0031  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0032  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0033  * POSSIBILITY OF SUCH DAMAGE.
0034  */
0035
0036 #ifndef _RTEMS_RINGBUF_H
0037 #define _RTEMS_RINGBUF_H
0038
0039 #include <rtems.h>
0040
0041 #ifndef RINGBUF_QUEUE_LENGTH
0042 #define RINGBUF_QUEUE_LENGTH 128
0043 #endif
0044
0045 typedef struct {
0046   uint8_t buffer[RINGBUF_QUEUE_LENGTH];
0047   volatile int  head;
0048   volatile int  tail;
0049   rtems_interrupt_lock lock;
0050 } Ring_buffer_t;
0051
0052 #define Ring_buffer_Initialize( _buffer ) \
0053   do { \
0054     (_buffer)->head = (_buffer)->tail = 0; \
0055     rtems_interrupt_lock_initialize(&(_buffer)->lock, "ring buffer"); \
0056   } while ( 0 )
0057
0058 #define Ring_buffer_Destory( _buffer ) \
0059   do { \
0060     rtems_interrupt_lock_destroy(&(_buffer)->lock); \
0061   } while ( 0 )
0062
0063 #define Ring_buffer_Is_empty( _buffer ) \
0064    ( (_buffer)->head == (_buffer)->tail )
0065
0066 #define Ring_buffer_Is_full( _buffer ) \
0067    ( (_buffer)->head == ((_buffer)->tail + 1) % RINGBUF_QUEUE_LENGTH )
0068
0069 #define Ring_buffer_Add_character( _buffer, _ch ) \
0070   do { \
0071     rtems_interrupt_lock_context lock_context; \
0072     \
0073     rtems_interrupt_lock_acquire( &(_buffer)->lock, &lock_context ); \
0074       (_buffer)->tail = ((_buffer)->tail+1) % RINGBUF_QUEUE_LENGTH; \
0075       (_buffer)->buffer[ (_buffer)->tail ] = (_ch); \
0076     rtems_interrupt_lock_release( &(_buffer)->lock, &lock_context ); \
0077   } while ( 0 )
0078
0079 #define Ring_buffer_Remove_character( _buffer, _ch ) \
0080   do { \
0081     rtems_interrupt_lock_context lock_context; \
0082     \
0083     rtems_interrupt_lock_acquire( &(_buffer)->lock, &lock_context ); \
0084       (_buffer)->head = ((_buffer)->head+1) % RINGBUF_QUEUE_LENGTH; \
0085       (_ch) = (_buffer)->buffer[ (_buffer)->head ]; \
0086     rtems_interrupt_lock_release( &(_buffer)->lock, &lock_context ); \
0087   } while ( 0 )
0088
0089 #endif