/*
   * Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup     sys_util
   * @{
   *
   * @file
   * @brief       Bitfield auxillary functions
   *
   * @author      Kaspar Schleiser <kaspar@schleiser.de>
   *
   * @}
   */
  
  #include <stdint.h>
  #include "bitfield.h"
  #include "irq.h"
  
  int bf_get_unset(uint8_t field[], int size)
  {
      int result = -1;
      int nbytes = (size + 7) / 8;
      int i = 0;
  
      unsigned state = irq_disable();
  
      /* skip full bytes */
      for (int j = 0; (j < nbytes) && (field[j] == 255); j++) {
          i += 8;
      }
  
      for (; i < size; i++) {
          if (!bf_isset(field, i)) {
              bf_set(field, i);
              result = i;
              break;
          }
      }
  
      irq_restore(state);
      return(result);
  }