Colony

/**

 * Copyright (c) 2007 Colony Project

 * 

 * 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.

 **/

/** @file ring_buffer.h

 * @brief Ring Buffer

 *

 * Include macros to create a ring buffer. Originally written for 15-410.

 * Modified for use in ATMega128 serial driver

 *

 * @author Cornell Wright (cgwright)

 * @author Jason P. Winters (jpwinter)

 *

 **/

#ifndef _RING_BUFFER_H

#define _RING_BUFFER_H

/** @brief Creates the struct for a new ring buffer. This just expands to a

 *	structure definition and thus should be invoked in the global context.

 *

 *	@param struct_name Name of the ring buffer struct.

 *

 *	@param size The size of the buffer to create.

 *

 *	@param type The type of object that the queue is to hold.

 *

 *	@param ... Name or names of the instance or instances of the ring buffer(s)

 *	to be created.

 */

#define RING_BUFFER_NEW(struct_name, size, type, ...)	\

	struct struct_name {	\

		type queue[size];	\

		uint8_t start;			\

		uint8_t end;			\

		uint8_t buffer_size;			\

	} __VA_ARGS__

/** @brief Initializes the ring buffer, setting its size to the correct value

 *

 *	@param buf The ring buffer to initialize.

 *

 *  @param size The size of the ring buffer (in array elements)

 */

#define RING_BUFFER_INIT(buf, size) 			\

	do {										\

		(buf).buffer_size = size;				\

	} while(0)

/** @brief Sets the specified ring buffer to be empty.

 *

 *	@param buf The ring buffer to make empty.

 */

#define RING_BUFFER_CLEAR(buf)	\

	do {						\

		(buf).start = 0;		\

		(buf).end = 0;			\

	} while (0)

/** @brief Returns true if the ring buffer specified is empty.

 *

 *	@param buf The buffer to check emptiness of.

 */

#define RING_BUFFER_EMPTY(buf) ((buf).start == (buf).end)

/** @brief Returns true if the ring buffer specified is full.

 *

 *	@param buf The buffer to check fullness of.

 */

#define RING_BUFFER_FULL(buf)	\

		(((buf).end + 1) % (buf).buffer_size == (buf).start)

/** @brief Adds val to ring buffer buf. Note that val must be of the type

 *	used in creating the ring buffer to prevent the compiler from spewing

 *	confusing errors. Also, this assumes that the ring buffer is not full.

 *

 *	@param buf The ring buffer to add to.

 *	@param val The value to add.

 */

#define RING_BUFFER_ADD(buf, val)		\

	do {								\

		(buf).queue[(buf).end] = val;	\

		(buf).end = ((buf).end + 1) % (buf).buffer_size;	\

	} while (0)

/** @brief Removes the value at the head of the ring buffer and puts it in

 *	val_ret. Note that val_ret must be the same type used in creating the ring

 *	buffer to prevent the compiler from spewing confusing errors. Also, this

 *	assumes that the ring buffer is not empty.

 *

 *	@param buf The ring buffer to remove from.

 *	@param val_ret Where to put the value removed from the head of the ring

 *	buffer.

 */

#define RING_BUFFER_REMOVE(buf, val_ret)	\

	do {	\

		(val_ret) = (buf).queue[(buf).start];	\

		(buf).start = ((buf).start + 1) % (buf).buffer_size;	\

	} while (0)

/** @brief Checks the value at the head of the ring buffer without removing it

 *  and puts it into val_ret. Note that val_ret must be the same type used in

 *  creating the ring buffer to prevent the compiler from spewing confusing

 *  errors. Also, this assumes that the ring buffer is not empty.

 *

 *  @param buf The ring buffer to check from

 *  @param val_ret where to put the value checked from the head of the ring

 */

 #define RING_BUFFER_PEEK(buf, val_ret)  \

  do { \

    (val_ret) = (buf).queue[(buf).start]; \

  } while(0)

#endif /* _RING_BUFFER_H */