#include "circbuf.h"

#include "util.h"
#include "assert.h"

struct circbuf circbuf_init(size_t size, unsigned int len)
{
    struct circbuf new;
    new.len = powof2(len);
    new.len = len;
    new.data = calloc(sizeof(short), new.len);
    new.read = new.write = 0;

    return new;
}

int cbuf_size(struct circbuf *buf) {
    return buf->write - buf->read;
}

int cbuf_empty(struct circbuf *buf) {
    return buf->read == buf->write;
}

int cbuf_full(struct circbuf *buf) {
    return cbuf_size(buf) == buf->len;
}

uint32_t cbuf_mask(struct circbuf *buf, uint32_t n) {
    return n & (buf->len-1);
}

void cbuf_push(struct circbuf *buf, short data) {
    assert(!cbuf_full(buf));

    buf->data[cbuf_mask(buf,buf->write++)] = data;
}

short cbuf_shift(struct circbuf *buf) {
    assert(!cbuf_empty(buf));
    return buf->data[cbuf_mask(buf, buf->read++)];
}