/* Copyright (c) 2013 Nordic Semiconductor. All Rights Reserved.
 *
 * The information contained herein is property of Nordic Semiconductor ASA.
 * Terms and conditions of usage are described in detail in NORDIC
 * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
 *
 * Licensees are granted free, non-transferable use of the information. NO
 * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
 * the file.
 *
 */

#include "app_fifo.h"
#include "nrf_error.h"
#include "app_util.h"

static __INLINE uint32_t fifo_length(app_fifo_t * p_fifo)
{
  uint32_t tmp = p_fifo->read_pos;
  return p_fifo->write_pos - tmp;
}

#define FIFO_LENGTH fifo_length(p_fifo)  /**< Macro for calculating the FIFO length. */


uint32_t app_fifo_init(app_fifo_t * p_fifo, uint8_t * p_buf, uint16_t buf_size)
{
    // Check buffer for null pointer.
    if (p_buf == NULL)
    {
        return NRF_ERROR_NULL;
    }

    // Check that the buffer size is a power of two.
    if (!IS_POWER_OF_TWO(buf_size))
    {
        return NRF_ERROR_INVALID_LENGTH;
    }

    p_fifo->p_buf         = p_buf;
    p_fifo->buf_size_mask = buf_size - 1;
    p_fifo->read_pos      = 0;
    p_fifo->write_pos     = 0;

    return NRF_SUCCESS;
}


uint32_t app_fifo_put(app_fifo_t * p_fifo, uint8_t byte)
{
    if (FIFO_LENGTH <= p_fifo->buf_size_mask)
    {
        p_fifo->p_buf[p_fifo->write_pos & p_fifo->buf_size_mask] = byte;
        p_fifo->write_pos++;
        return NRF_SUCCESS;
    }

    return NRF_ERROR_NO_MEM;
}


uint32_t app_fifo_get(app_fifo_t * p_fifo, uint8_t * p_byte)
{
    if (FIFO_LENGTH != 0)
    {
        *p_byte = p_fifo->p_buf[p_fifo->read_pos & p_fifo->buf_size_mask];
        p_fifo->read_pos++;
        return NRF_SUCCESS;
    }

    return NRF_ERROR_NOT_FOUND;

}

uint32_t app_fifo_flush(app_fifo_t * p_fifo)
{
    p_fifo->read_pos = p_fifo->write_pos;
    return NRF_SUCCESS;
}
