LXR linux/lib/clz

   1/*
   2 * lib/clz_ctz.c
   3 *
   4 * Copyright (C) 2013 Chanho Min <chanho.min@lge.com>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 * The functions in this file aren't called directly, but are required by
  10 * GCC builtins such as __builtin_ctz, and therefore they can't be removed
  11 * despite appearing unreferenced in kernel source.
  12 *
  13 * __c[lt]z[sd]i2 can be overridden by linking arch-specific versions.
  14 */
  15
  16#include <linux/export.h>
  17#include <linux/kernel.h>
  18
  19int __weak __ctzsi2(int val);
  20int __weak __ctzsi2(int val)
  21{
  22        return __ffs(val);
  23}
  24EXPORT_SYMBOL(__ctzsi2);
  25
  26int __weak __clzsi2(int val);
  27int __weak __clzsi2(int val)
  28{
  29        return 32 - fls(val);
  30}
  31EXPORT_SYMBOL(__clzsi2);
  32
  33int __weak __clzdi2(long val);
  34int __weak __ctzdi2(long val);
  35#if BITS_PER_LONG == 32
  36
  37int __weak __clzdi2(long val)
  38{
  39        return 32 - fls((int)val);
  40}
  41EXPORT_SYMBOL(__clzdi2);
  42
  43int __weak __ctzdi2(long val)
  44{
  45        return __ffs((u32)val);
  46}
  47EXPORT_SYMBOL(__ctzdi2);
  48
  49#elif BITS_PER_LONG == 64
  50
  51int __weak __clzdi2(long val)
  52{
  53        return 64 - fls64((u64)val);
  54}
  55EXPORT_SYMBOL(__clzdi2);
  56
  57int __weak __ctzdi2(long val)
  58{
  59        return __ffs64((u64)val);
  60}
  61EXPORT_SYMBOL(__ctzdi2);
  62
  63#else
  64#error BITS_PER_LONG not 32 or 64
  65#endif
  66