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/**
* Ringbuffer header
*
* Copyright (C) 2013 Freie Universität Berlin
* Copyright (C) 2013 INRIA
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*
* @ingroup core_util
* @{
* @file
* @author Kaspar Schleiser <kaspar@schleiser.de>
* @author René Kijewski <rene.kijewski@fu-berlin.de>
* @}
*/
#ifndef RINGBUFFER_H
#define RINGBUFFER_H
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Ringbuffer.
* @details Non thread-safe FIFO ringbuffer implementation around a `char` array.
*/
typedef struct {
char *buf; /**< Buffer to operate on. */
unsigned int size; /**< Size of buf. */
unsigned int start; /**< Current read position in the ring buffer. */
unsigned int avail; /**< Number of elements available for reading. */
} ringbuffer_t;
/**
* @def RINGBUFFER_INIT(BUF)
* @brief Initialize a ringbuffer.
* @details This macro is meant for static ringbuffers.
* @param[in] BUF Buffer to use for the ringbuffer. The size is deduced through `sizeof (BUF)`.
* @returns The static initializer.
*/
#define RINGBUFFER_INIT(BUF) { (BUF), sizeof (BUF), 0, 0 }
/**
* @brief Initialize a ringbuffer.
* @param[out] rb Datum to initialize.
* @param[in] buffer Buffer to use by rb.
* @param[in] bufsize `sizeof (buffer)`
*/
static inline void ringbuffer_init(ringbuffer_t *__restrict rb, char *buffer, unsigned bufsize)
{
rb->buf = buffer;
rb->size = bufsize;
rb->start = 0;
rb->avail = 0;
}
/**
* @brief Add an element to the ringbuffer.
* @details If rb is full, then the oldest element gets overwritten.
* Test ringbuffer_full() first if overwriting is not intended.
* @param[in,out] rb Ringbuffer to operate on.
* @param[in] c Element to add.
* @returns The element that was dropped, iff the buffer was full.
* -1 iff the buffer was not full.
*/
int ringbuffer_add_one(ringbuffer_t *__restrict rb, char c);
/**
* @brief Add a number of elements to the ringbuffer.
* @details Only so many elements are added as fit in the ringbuffer.
* No elements get overwritten.
* If this is not the intended behavior, then use ringbuffer_add_one() in a loop instead.
* @param[in,out] rb Ringbuffer to operate on.
* @param[in] buf Buffer to add elements from.
* @param[in] n Maximum number of elements to add.
* @returns Number of elements actually added. 0 if rb is full.
*/
unsigned ringbuffer_add(ringbuffer_t *__restrict rb, const char *buf, unsigned n);
/**
* @brief Peek and remove oldest element from the ringbuffer.
* @param[in,out] rb Ringbuffer to operate on.
* @returns The oldest element that was added, or `-1` if rb is empty.
*/
int ringbuffer_get_one(ringbuffer_t *__restrict rb);
/**
* @brief Read and remove a number of elements from the ringbuffer.
* @param[in,out] rb Ringbuffer to operate on.
* @param[out] buf Buffer to write into.
* @param[in] n Read at most n elements.
* @returns Number of elements actually read.
*/
unsigned ringbuffer_get(ringbuffer_t *__restrict rb, char *buf, unsigned n);
/**
* @brief Remove a number of elements from the ringbuffer.
* @param[in,out] rb Ringbuffer to operate on.
* @param[in] n Read at most n elements.
* @returns Number of elements actually removed.
*/
unsigned ringbuffer_remove(ringbuffer_t *__restrict rb, unsigned n);
/**
* @brief Test if the ringbuffer is empty.
* @param[in,out] rb Ringbuffer to operate on.
* @returns 0 iff not empty
*/
static inline int ringbuffer_empty(const ringbuffer_t *__restrict rb)
{
return rb->avail == 0;
}
/**
* @brief Test if the ringbuffer is full.
* @param[in,out] rb Ringbuffer to operate on.
* @returns 0 iff not full
*/
static inline int ringbuffer_full(const ringbuffer_t *__restrict rb)
{
return rb->avail == rb->size;
}
/**
* @brief Return available space in ringbuffer
* @param[in,out] rb Ringbuffer to query.
* @returns number of available bytes
*/
static inline unsigned int ringbuffer_get_free(const ringbuffer_t *__restrict rb)
{
return rb->size - rb->avail;
}
/**
* @brief Read, but don't remove, the oldest element in the buffer.
* @param[in] rb Ringbuffer to operate on.
* @returns Same as ringbuffer_get_one()
*/
int ringbuffer_peek_one(const ringbuffer_t *__restrict rb);
/**
* @brief Read, but don't remove, the a number of element of the buffer.
* @param[in] rb Ringbuffer to operate on.
* @param[out] buf Buffer to write into.
* @param[in] n Read at most n elements.
* @returns Same as ringbuffer_get()
*/
unsigned ringbuffer_peek(const ringbuffer_t *__restrict rb, char *buf, unsigned n);
#ifdef __cplusplus
}
#endif
#endif /* RINGBUFFER_H */