Commit 048fa2df authored by Catalin Marinas's avatar Catalin Marinas

generic: Implement generic ffs/fls using __builtin_* functions

This patch implements ffs, __ffs, fls, __fls using __builtin_* gcc
functions. These header files can be used by other architectures that
rely on the gcc builtins.
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
parent 0753f70f
#ifndef _ASM_GENERIC_BITOPS_BUILTIN___FFS_H_
#define _ASM_GENERIC_BITOPS_BUILTIN___FFS_H_
/**
* __ffs - find first bit in word.
* @word: The word to search
*
* Undefined if no bit exists, so code should check against 0 first.
*/
static __always_inline unsigned long __ffs(unsigned long word)
{
return __builtin_ctzl(word);
}
#endif
#ifndef _ASM_GENERIC_BITOPS_BUILTIN___FLS_H_
#define _ASM_GENERIC_BITOPS_BUILTIN___FLS_H_
/**
* __fls - find last (most-significant) set bit in a long word
* @word: the word to search
*
* Undefined if no set bit exists, so code should check against 0 first.
*/
static __always_inline unsigned long __fls(unsigned long word)
{
return (sizeof(word) * 8) - 1 - __builtin_clzl(word);
}
#endif
#ifndef _ASM_GENERIC_BITOPS_BUILTIN_FFS_H_
#define _ASM_GENERIC_BITOPS_BUILTIN_FFS_H_
/**
* ffs - find first bit set
* @x: the word to search
*
* This is defined the same way as
* the libc and compiler builtin ffs routines, therefore
* differs in spirit from the above ffz (man ffs).
*/
static __always_inline int ffs(int x)
{
return __builtin_ffs(x);
}
#endif
#ifndef _ASM_GENERIC_BITOPS_BUILTIN_FLS_H_
#define _ASM_GENERIC_BITOPS_BUILTIN_FLS_H_
/**
* fls - find last (most-significant) bit set
* @x: the word to search
*
* This is defined the same way as ffs.
* Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
*/
static __always_inline int fls(int x)
{
return x ? sizeof(x) * 8 - __builtin_clz(x) : 0;
}
#endif
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