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authorSzabolcs Nagy <nsz@port70.net>2017-04-19 00:20:54 +0200
committerRich Felker <dalias@aerifal.cx>2017-08-29 21:47:10 -0400
commit06fbefd10046a0fae7e588b7c6d25fb51811b931 (patch)
tree032c4ece67f6217ceb354ebff4c9889f2f0133eb /arch/powerpc64
parent3356177979bea717451362e746252ed38de77514 (diff)
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add a_clz_64 helper function
counts leading zero bits of a 64bit int, undefined on zero input. (has nothing to do with atomics, added to atomic.h so target specific helper functions are together.) there is a logarithmic generic implementation and another in terms of a 32bit a_clz_32 on targets where that's available.
Diffstat (limited to 'arch/powerpc64')
-rw-r--r--arch/powerpc64/atomic_arch.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/powerpc64/atomic_arch.h b/arch/powerpc64/atomic_arch.h
index 269d79c6..17cababd 100644
--- a/arch/powerpc64/atomic_arch.h
+++ b/arch/powerpc64/atomic_arch.h
@@ -61,3 +61,10 @@ static inline void a_crash()
{
__asm__ __volatile__ (".long 0");
}
+
+#define a_clz_64 a_clz_64
+static inline int a_clz_64(uint64_t x)
+{
+ __asm__ ("cntlzd %0, %1" : "=r"(x) : "r"(x));
+ return x;
+}