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| author | Herbert Valerio Riedel <hvr@gnu.org> | 2014-08-14 12:32:32 +0200 |
|---|---|---|
| committer | Herbert Valerio Riedel <hvr@gnu.org> | 2014-08-31 15:47:32 +0200 |
| commit | a8a969ae7a05e408b29961d0a2ea621a16d73d3e (patch) | |
| tree | 7e7e77b19c9d086347b91c763dc4f6ef063bde28 /libraries/base/GHC/Int.hs | |
| parent | 393b820233caa00e428affc28e090b496d181664 (diff) | |
| download | haskell-a8a969ae7a05e408b29961d0a2ea621a16d73d3e.tar.gz | |
Add `FiniteBits(count{Leading,Trailing}Zeros)`
This exposes the newly added CLZ/CTZ primops from
e0c1767d0ea8d12e0a4badf43682a08784e379c6 (re #9340)
via two new methods `countLeadingZeros` and `countTrailingZeros`
in the `Data.Bits.FiniteBits` class.
The original proposal can be found at
http://www.haskell.org/pipermail/libraries/2014-August/023567.html
Test Plan: successful validate
Reviewers: ekmett, tibbe
GHC Trac Issues: #9532
Differential Revision: https://phabricator.haskell.org/D158
Diffstat (limited to 'libraries/base/GHC/Int.hs')
| -rw-r--r-- | libraries/base/GHC/Int.hs | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/libraries/base/GHC/Int.hs b/libraries/base/GHC/Int.hs index 467b3f4e30..a9743ce1a0 100644 --- a/libraries/base/GHC/Int.hs +++ b/libraries/base/GHC/Int.hs @@ -165,6 +165,8 @@ instance Bits Int8 where instance FiniteBits Int8 where finiteBitSize _ = 8 + countLeadingZeros (I8# x#) = I# (word2Int# (clz8# (int2Word# x#))) + countTrailingZeros (I8# x#) = I# (word2Int# (ctz8# (int2Word# x#))) {-# RULES "fromIntegral/Int8->Int8" fromIntegral = id :: Int8 -> Int8 @@ -324,6 +326,8 @@ instance Bits Int16 where instance FiniteBits Int16 where finiteBitSize _ = 16 + countLeadingZeros (I16# x#) = I# (word2Int# (clz16# (int2Word# x#))) + countTrailingZeros (I16# x#) = I# (word2Int# (ctz16# (int2Word# x#))) {-# RULES "fromIntegral/Word8->Int16" fromIntegral = \(W8# x#) -> I16# (word2Int# x#) @@ -489,6 +493,8 @@ instance Bits Int32 where instance FiniteBits Int32 where finiteBitSize _ = 32 + countLeadingZeros (I32# x#) = I# (word2Int# (clz32# (int2Word# x#))) + countTrailingZeros (I32# x#) = I# (word2Int# (ctz32# (int2Word# x#))) {-# RULES "fromIntegral/Word8->Int32" fromIntegral = \(W8# x#) -> I32# (word2Int# x#) @@ -871,6 +877,13 @@ uncheckedIShiftRA64# = uncheckedIShiftRA# instance FiniteBits Int64 where finiteBitSize _ = 64 +#if WORD_SIZE_IN_BITS < 64 + countLeadingZeros (I64# x#) = I# (word2Int# (clz64# (int64ToWord64# x#))) + countTrailingZeros (I64# x#) = I# (word2Int# (ctz64# (int64ToWord64# x#))) +#else + countLeadingZeros (I64# x#) = I# (word2Int# (clz64# (int2Word# x#))) + countTrailingZeros (I64# x#) = I# (word2Int# (ctz64# (int2Word# x#))) +#endif instance Real Int64 where toRational x = toInteger x % 1 |