Colony

/** @file 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)

 *

 *        @bugs Could not create buffer of non byte-sized elements due to modding with sizeof(queue).  

 *                   Fixed 3/2/07, Felix Duvallet and Brad Neuman

 */

#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 */