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 None known.

 */

#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;                        \

        } __VA_ARGS__

#define RING_BUFFER_BIT_NEW(struct_name, size, ...)        \

        struct struct_name {        \

                int8_t queue[(size / 8) + 1];        \

                uint16_t start;        \

                uint16_t end;        \

        } __VA_ARGS__

/** @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)

#define RING_BUFFER_BIT_CLEAR(buf) RING_BUFFER_CLEAR(buf)

/** @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)

#define RING_BUFFER_BIT_EMPTY(buf) RING_BUFFER_EMPTY(buf)

/** @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) % sizeof((buf).queue) == (buf).start)

#define RING_BUFFER_BIT_FULL(buf) RING_BUFFER_FULL(buf)

/** @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) % sizeof((buf).queue);        \

        } while (0)

#define RING_BUFFER_BIT_ADD(buf, val)        \

        do {                                                                \

                if (val) {                                                \

                        (buf).queue[((buf).end >> 3) & 0xff] |= _BV((buf).end & 0x7);        \

                }                                                                \

                else {                                                        \

                        (buf).queue[((buf).end >> 3) & 0xff] &= ~_BV((buf).end & 0x7);        \

                }                                                                \

                (buf).end = ((buf).end + 1) % (sizeof((buf).queue) << 3);                        \

        } 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) % sizeof((buf).queue);        \

        } while (0)

#define RING_BUFFER_BIT_REMOVE(buf, val_ret)        \

        do {        \

                (val_ret) = ((buf).queue[((buf).start >> 3) & 0xff] & _BV((buf).start & 0x7)) ? 1 : 0;        \

                (buf).start = ((buf).start + 1) % (sizeof((buf).queue) << 3);        \

        } while (0)

#endif /* _RING_BUFFER_H */