lib/clz_ctz.c

   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
  19 int __weak __ctzsi2(int val);
  20 int __weak __ctzsi2(int val)
  21 {
  22         return __ffs(val);
  23 }
  24 EXPORT_SYMBOL(__ctzsi2);
  25
  26 int __weak __clzsi2(int val);
  27 int __weak __clzsi2(int val)
  28 {
  29         return 32 - fls(val);
  30 }
  31 EXPORT_SYMBOL(__clzsi2);
  32
  33 int __weak __clzdi2(long val);
  34 int __weak __ctzdi2(long val);
  35 #if BITS_PER_LONG == 32
  36
  37 int __weak __clzdi2(long val)
  38 {
  39         return 32 - fls((int)val);
  40 }
  41 EXPORT_SYMBOL(__clzdi2);
  42
  43 int __weak __ctzdi2(long val)
  44 {
  45         return __ffs((u32)val);
  46 }
  47 EXPORT_SYMBOL(__ctzdi2);
  48
  49 #elif BITS_PER_LONG == 64
  50
  51 int __weak __clzdi2(long val)
  52 {
  53         return 64 - fls64((u64)val);
  54 }
  55 EXPORT_SYMBOL(__clzdi2);
  56
  57 int __weak __ctzdi2(long val)
  58 {
  59         return __ffs64((u64)val);
  60 }
  61 EXPORT_SYMBOL(__ctzdi2);
  62
  63 #else
  64 #error BITS_PER_LONG not 32 or 64
  65 #endif