LXR linux/lib/clz

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * lib/clz_ctz.c
   4 *
   5 * Copyright (C) 2013 Chanho Min <chanho.min@lge.com>
   6 *
   7 * The functions in this file aren't called directly, but are required by
   8 * GCC builtins such as __builtin_ctz, and therefore they can't be removed
   9 * despite appearing unreferenced in kernel source.
  10 *
  11 * __c[lt]z[sd]i2 can be overridden by linking arch-specific versions.
  12 */
  13
  14#include <linux/export.h>
  15#include <linux/kernel.h>
  16
  17int __weak __ctzsi2(int val);
  18int __weak __ctzsi2(int val)
  19{
  20        return __ffs(val);
  21}
  22EXPORT_SYMBOL(__ctzsi2);
  23
  24int __weak __clzsi2(int val);
  25int __weak __clzsi2(int val)
  26{
  27        return 32 - fls(val);
  28}
  29EXPORT_SYMBOL(__clzsi2);
  30
  31int __weak __clzdi2(long val);
  32int __weak __ctzdi2(long val);
  33#if BITS_PER_LONG == 32
  34
  35int __weak __clzdi2(long val)
  36{
  37        return 32 - fls((int)val);
  38}
  39EXPORT_SYMBOL(__clzdi2);
  40
  41int __weak __ctzdi2(long val)
  42{
  43        return __ffs((u32)val);
  44}
  45EXPORT_SYMBOL(__ctzdi2);
  46
  47#elif BITS_PER_LONG == 64
  48
  49int __weak __clzdi2(long val)
  50{
  51        return 64 - fls64((u64)val);
  52}
  53EXPORT_SYMBOL(__clzdi2);
  54
  55int __weak __ctzdi2(long val)
  56{
  57        return __ffs64((u64)val);
  58}
  59EXPORT_SYMBOL(__ctzdi2);
  60
  61#else
  62#error BITS_PER_LONG not 32 or 64
  63#endif
  64