/* Count leading and trailing zeros functions
   *
   * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public Licence
   * as published by the Free Software Foundation; either version
   * 2 of the Licence, or (at your option) any later version.
   */

  #ifndef _LINUX_BITOPS_COUNT_ZEROS_H_
  #define _LINUX_BITOPS_COUNT_ZEROS_H_

  
  #include <asm/bitops.h>
  
  /**
   * count_leading_zeros - Count the number of zeros from the MSB back
   * @x: The value
   *
   * Count the number of leading zeros from the MSB going towards the LSB in @x.
   *
   * If the MSB of @x is set, the result is 0.
   * If only the LSB of @x is set, then the result is BITS_PER_LONG-1.
   * If @x is 0 then the result is COUNT_LEADING_ZEROS_0.
   */
  static inline int count_leading_zeros(unsigned long x)
  {
  	if (sizeof(x) == 4)
  		return BITS_PER_LONG - fls(x);
  	else
  		return BITS_PER_LONG - fls64(x);
  }
  
  #define COUNT_LEADING_ZEROS_0 BITS_PER_LONG
  
  /**
   * count_trailing_zeros - Count the number of zeros from the LSB forwards
   * @x: The value
   *
   * Count the number of trailing zeros from the LSB going towards the MSB in @x.
   *
   * If the LSB of @x is set, the result is 0.
   * If only the MSB of @x is set, then the result is BITS_PER_LONG-1.
   * If @x is 0 then the result is COUNT_TRAILING_ZEROS_0.
   */
  static inline int count_trailing_zeros(unsigned long x)
  {
  #define COUNT_TRAILING_ZEROS_0 (-1)
  
  	if (sizeof(x) == 4)
  		return ffs(x);
  	else
  		return (x != 0) ? __ffs(x) : COUNT_TRAILING_ZEROS_0;
  }

  #endif /* _LINUX_BITOPS_COUNT_ZEROS_H_ */