lib/clz_ctz.c

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