#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include "ringbuffer.h"

void _ringBufferIncReader(struct ringBuffer *buf) {
  buf->reader++;
  if (buf->reader >= buf->capacity) {
    buf->reader = 0;
  }
}

void _ringBufferIncWriter(struct ringBuffer *buf) {
  buf->writer++;
  if (buf->writer >= buf->capacity) {
    buf->writer = 0;
  }

  if (buf->writer == buf->reader) {
    // we incremented the writer and now it is equal to reader
    // this means, the writer is overtaking the reader
    // so push the reader forward, even if we are
    // loosing data but this is how ring buffers work, eh?
    _ringBufferIncReader(buf);
  }
}

void ringBufferCreate(int capacity, struct ringBuffer *out) {
  out->buffer = malloc(capacity * sizeof(uint8_t));
  out->capacity = capacity;
  out->reader = 0;
  out->writer = 0;
}

void ringBufferDestroy(struct ringBuffer *buf) {
  free(buf->buffer);
}

int ringBufferRead(struct ringBuffer *buf, uint8_t *out) {
  if (buf->reader != buf->writer) {
    // we have data to read
    memcpy(out, &buf->buffer[buf->reader], sizeof(uint8_t));
    _ringBufferIncReader(buf);
    return 0;
  } else {
    // nothing to read
    return 1;
  }
}

void ringBufferWrite(struct ringBuffer *buf, uint8_t *in) {
  memcpy(&buf->buffer[buf->writer], in, sizeof(uint8_t));
  _ringBufferIncWriter(buf);
}