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lib/clz_ctz.c 1.3 KB
81f7e3824   Eric Lee   Initial Release, ...
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  /*
   * lib/clz_ctz.c
   *
   * Copyright (C) 2013 Chanho Min <chanho.min@lge.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   * The functions in this file aren't called directly, but are required by
   * GCC builtins such as __builtin_ctz, and therefore they can't be removed
   * despite appearing unreferenced in kernel source.
   *
   * __c[lt]z[sd]i2 can be overridden by linking arch-specific versions.
   */
  
  #include <linux/export.h>
  #include <linux/kernel.h>
  
  int __weak __ctzsi2(int val);
  int __weak __ctzsi2(int val)
  {
  	return __ffs(val);
  }
  EXPORT_SYMBOL(__ctzsi2);
  
  int __weak __clzsi2(int val);
  int __weak __clzsi2(int val)
  {
  	return 32 - fls(val);
  }
  EXPORT_SYMBOL(__clzsi2);
  
  int __weak __clzdi2(long val);
  int __weak __ctzdi2(long val);
  #if BITS_PER_LONG == 32
  
  int __weak __clzdi2(long val)
  {
  	return 32 - fls((int)val);
  }
  EXPORT_SYMBOL(__clzdi2);
  
  int __weak __ctzdi2(long val)
  {
  	return __ffs((u32)val);
  }
  EXPORT_SYMBOL(__ctzdi2);
  
  #elif BITS_PER_LONG == 64
  
  int __weak __clzdi2(long val)
  {
  	return 64 - fls64((u64)val);
  }
  EXPORT_SYMBOL(__clzdi2);
  
  int __weak __ctzdi2(long val)
  {
  	return __ffs64((u64)val);
  }
  EXPORT_SYMBOL(__ctzdi2);
  
  #else
  #error BITS_PER_LONG not 32 or 64
  #endif