ring_t

ring.c

#include "ring.h"

int ring_add(ring_t *ring, ring_data_t data)
{
    ring_pos_t next_head = (ring->head + 1) % RING_SIZE;
    if (next_head != ring->tail) {
        ring->data[ring->head] = data;
        ring->head = next_head;
        return 0;
    } else {
        return -1;
    }
}

int ring_del(ring_t *ring)
{
    if (ring->head != ring->tail) {
        ring_data_t data = ring->data[ring->tail];
        ring->tail = (ring->tail + 1) % RING_SIZE;
        return data;
    } else {
        return -1;
    }
}

ring.h

#ifndef RING_H
#define RING_H

#include <stdint.h>

#define RING_SIZE 32
typedef uint8_t ring_data_t;
typedef uint16_t ring_pos_t;

typedef struct {
    volatile ring_pos_t head;
    volatile ring_pos_t tail;
    volatile ring_data_t data[RING_SIZE];
} ring_t;

int ring_add(ring_t *ring, ring_data_t data);
int ring_del(ring_t *ring);

#endif // RING_H