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authorAndre McCurdy <armccurdy@gmail.com>2018-04-18 17:41:00 -0700
committerRich Felker <dalias@aerifal.cx>2018-04-19 12:27:16 -0400
commitea489b8b0d89e391455689b7cc397d0c261677c9 (patch)
treea810bb435fbac14d1269bf5a5150be808cdf795f /arch
parent0c6abb58820398ac995305d88f3e6a9f0a692eb7 (diff)
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provide optimized a_ctz_32 for arm
Provide an ARM specific a_ctz_32 helper function for architecture versions for which it can be implemented efficiently via the "rbit" instruction (ie all Thumb-2 capable versions of ARM v6 and above).
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/atomic_arch.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/arm/atomic_arch.h b/arch/arm/atomic_arch.h
index c5c56f8..72fcddb 100644
--- a/arch/arm/atomic_arch.h
+++ b/arch/arm/atomic_arch.h
@@ -91,4 +91,16 @@ static inline int a_clz_32(uint32_t x)
return x;
}
+#if __ARM_ARCH_6T2__ || __ARM_ARCH_7A__ || __ARM_ARCH_7R__ || __ARM_ARCH >= 7
+
+#define a_ctz_32 a_ctz_32
+static inline int a_ctz_32(uint32_t x)
+{
+ uint32_t xr;
+ __asm__ ("rbit %0, %1" : "=r"(xr) : "r"(x));
+ return a_clz_32(xr);
+}
+
+#endif
+
#endif