From 7172e26cc446556e6b8241549d5d188b5cb0cd37 Mon Sep 17 00:00:00 2001 From: Gabe Black Date: Wed, 1 Jul 2009 22:16:36 -0700 Subject: ARM: Add a findLsbSet function and use it to implement clz. --- src/base/bitfield.hh | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'src/base') diff --git a/src/base/bitfield.hh b/src/base/bitfield.hh index 28093a5d4..cc3695159 100644 --- a/src/base/bitfield.hh +++ b/src/base/bitfield.hh @@ -161,4 +161,21 @@ findMsbSet(uint64_t val) { return msb; } +/** + * Returns the bit position of the LSB that is set in the input + */ +inline int +findLsbSet(uint64_t val) { + int lsb = 0; + if (!val) + return sizeof(val) * 8; + if (!bits(val, 31,0)) { lsb += 32; val >>= 32; } + if (!bits(val, 15,0)) { lsb += 16; val >>= 16; } + if (!bits(val, 7,0)) { lsb += 8; val >>= 8; } + if (!bits(val, 3,0)) { lsb += 4; val >>= 4; } + if (!bits(val, 1,0)) { lsb += 2; val >>= 2; } + if (!bits(val, 0,0)) { lsb += 1; } + return lsb; +} + #endif // __BASE_BITFIELD_HH__ -- cgit v1.2.3