提交 93635133 编写于 作者: A Akinobu Mita 提交者: Linus Torvalds

[PATCH] arm: fix undefined reference to generic_fls

This patch defines constant_fls() instead of removed generic_fls().
Signed-off-by: NAkinobu Mita <mita@miraclelinux.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
上级 f214ef3e
......@@ -344,13 +344,42 @@ static inline unsigned long __ffs(unsigned long word)
#else
static inline int constant_fls(int x)
{
int r = 32;
if (!x)
return 0;
if (!(x & 0xffff0000u)) {
x <<= 16;
r -= 16;
}
if (!(x & 0xff000000u)) {
x <<= 8;
r -= 8;
}
if (!(x & 0xf0000000u)) {
x <<= 4;
r -= 4;
}
if (!(x & 0xc0000000u)) {
x <<= 2;
r -= 2;
}
if (!(x & 0x80000000u)) {
x <<= 1;
r -= 1;
}
return r;
}
/*
* On ARMv5 and above those functions can be implemented around
* the clz instruction for much better code efficiency.
*/
#define fls(x) \
( __builtin_constant_p(x) ? generic_fls(x) : \
( __builtin_constant_p(x) ? constant_fls(x) : \
({ int __r; asm("clz\t%0, %1" : "=r"(__r) : "r"(x) : "cc"); 32-__r; }) )
#define fls64(x) generic_fls64(x)
#define ffs(x) ({ unsigned long __t = (x); fls(__t & -__t); })
......
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