| /* 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_ */ |