/* The MIT License (MIT)

Copyright (c) 2014 Anders Kalør

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE. */

#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>
/**
 * @file
 * Prototypes and structures for the ring buffer module.
 */

#ifndef RINGBUFFER_H
#define RINGBUFFER_H

/**
 * The size of a ring buffer.
 * Due to the design only <tt> RING_BUFFER_SIZE-1 </tt> items
 * can be contained in the buffer.
 * The buffer size must be a power of two.
 */
#define RING_BUFFER_SIZE 2048

#if (RING_BUFFER_SIZE & (RING_BUFFER_SIZE - 1)) != 0
#error "RING_BUFFER_SIZE must be a power of two"
#endif

/**
 * The type which is used to hold the size
 * and the indicies of the buffer.
 * Must be able to fit \c RING_BUFFER_SIZE .
 */
typedef uint32_t ring_buffer_size_t;

/**
 * Used as a modulo operator
 * as <tt> a % b = (a & (b − 1)) </tt>
 * where \c a is a positive index in the buffer and
 * \c b is the (power of two) size of the buffer.
 */
#define RING_BUFFER_MASK (RING_BUFFER_SIZE - 1)

/**
 * Simplifies the use of <tt>struct ring_buffer_t</tt>.
 */
typedef struct ring_buffer_t ring_buffer_t;

/**
 * Structure which holds a ring buffer.
 * The buffer contains a buffer array
 * as well as metadata for the ring buffer.
 */
struct ring_buffer_t
{
  /** Buffer memory. */
  char buffer[RING_BUFFER_SIZE];
  /** Index of tail. */
  ring_buffer_size_t tail_index;
  /** Index of head. */
  ring_buffer_size_t head_index;
};

/**
 * Initializes the ring buffer pointed to by <em>buffer</em>.
 * This function can also be used to empty/reset the buffer.
 * @param buffer The ring buffer to initialize.
 */
void ring_buffer_init(ring_buffer_t *buffer);

/**
 * Adds a byte to a ring buffer.
 * @param buffer The buffer in which the data should be placed.
 * @param data The byte to place.
 */
void ring_buffer_queue(ring_buffer_t *buffer, char data);

/**
 * Adds an array of bytes to a ring buffer.
 * @param buffer The buffer in which the data should be placed.
 * @param data A pointer to the array of bytes to place in the queue.
 * @param size The size of the array.
 */
void ring_buffer_queue_arr(ring_buffer_t *buffer, const char *data, ring_buffer_size_t size);

/**
 * Returns the oldest byte in a ring buffer.
 * @param buffer The buffer from which the data should be returned.
 * @param data A pointer to the location at which the data should be placed.
 * @return 1 if data was returned; 0 otherwise.
 */
uint8_t ring_buffer_dequeue(ring_buffer_t *buffer, char *data);

/**
 * Returns the <em>len</em> oldest bytes in a ring buffer.
 * @param buffer The buffer from which the data should be returned.
 * @param data A pointer to the array at which the data should be placed.
 * @param len The maximum number of bytes to return.
 * @return The number of bytes returned.
 */
uint8_t ring_buffer_dequeue_arr(ring_buffer_t *buffer, char *data, ring_buffer_size_t len);
/**
 * Peeks a ring buffer, i.e. returns an element without removing it.
 * @param buffer The buffer from which the data should be returned.
 * @param data A pointer to the location at which the data should be placed.
 * @param index The index to peek.
 * @return 1 if data was returned; 0 otherwise.
 */
uint8_t ring_buffer_peek(ring_buffer_t *buffer, char *data, ring_buffer_size_t index);

/**
 * Returns whether a ring buffer is empty.
 * @param buffer The buffer for which it should be returned whether it is empty.
 * @return 1 if empty; 0 otherwise.
 */
uint8_t ring_buffer_is_empty(ring_buffer_t *buffer);
/**
 * Returns whether a ring buffer is full.
 * @param buffer The buffer for which it should be returned whether it is full.
 * @return 1 if full; 0 otherwise.
 */
uint8_t ring_buffer_is_full(ring_buffer_t *buffer);

/**
 * Returns the number of items in a ring buffer.
 * @param buffer The buffer for which the number of items should be returned.
 * @return The number of items in the ring buffer.
 */
ring_buffer_size_t ring_buffer_num_items(ring_buffer_t *buffer);

uint8_t ring_buffer_dequeue_arr_no_ret(ring_buffer_t *buffer, ring_buffer_size_t len);

#endif /* RINGBUFFER_H */