Sketch:
#include "circularbuffer.h"
CircularBuffer cb;
void setup() {
Serial.begin(115200);
ElemType elem = {0};
int testBufferSize = 10; /* arbitrary size */
cbInit(&cb, testBufferSize);
/* Fill buffer with test elements 3 times */
for (elem.value = 0; elem.value < 3 * testBufferSize; ++ elem.value)
cbWrite(&cb, &elem);
/* Remove and print all elements */
while (!cbIsEmpty(&cb)) {
cbRead(&cb, &elem);
Serial.println(elem.value);
}
cbFree(&cb);
}
void loop()
{
}
Header file:
#ifndef CIRCULARBUFFER_H
#define CIRCULARBUFFER_H
#include <stdlib.h>
struct ElemType{ int value; };
/* Circular buffer object */
struct CircularBuffer{
int size; /* maximum number of elements */
int start; /* index of oldest element */
int end; /* index at which to write new element */
ElemType *elems; /* vector of elements */
};
void cbInit(CircularBuffer *cb, int size) {
cb->size = size + 1; /* include empty elem */
cb->start = 0;
cb->end = 0;
cb->elems = (ElemType *)calloc(cb->size, sizeof(ElemType));
}
void cbFree(CircularBuffer *cb) {
free(cb->elems); /* OK if null */ }
int cbIsFull(CircularBuffer *cb) {
return (cb->end + 1) % cb->size == cb->start; }
int cbIsEmpty(CircularBuffer *cb) {
return cb->end == cb->start; }
/* Write an element, overwriting oldest element if buffer is full. App can
choose to avoid the overwrite by checking cbIsFull(). */
void cbWrite(CircularBuffer *cb, ElemType *elem) {
cb->elems[cb->end] = *elem;
cb->end = (cb->end + 1) % cb->size;
if (cb->end == cb->start)
cb->start = (cb->start + 1) % cb->size; /* full, overwrite */
}
/* Read oldest element. App must ensure !cbIsEmpty() first. */
void cbRead(CircularBuffer *cb, ElemType *elem) {
*elem = cb->elems[cb->start];
cb->start = (cb->start + 1) % cb->size;
}
#endif