diff options
Diffstat (limited to 'libraries/base/GHC/Float/ConversionUtils.hs')
| -rw-r--r-- | libraries/base/GHC/Float/ConversionUtils.hs | 43 |
1 files changed, 6 insertions, 37 deletions
diff --git a/libraries/base/GHC/Float/ConversionUtils.hs b/libraries/base/GHC/Float/ConversionUtils.hs index 5b7036f503..5d9de64179 100644 --- a/libraries/base/GHC/Float/ConversionUtils.hs +++ b/libraries/base/GHC/Float/ConversionUtils.hs @@ -33,13 +33,10 @@ default () #define TO64 integerToInt64# -toByte64# :: Int64# -> Int# -toByte64# i = word2Int# (and# 255## (int2Word# (int64ToInt# i))) - -- Double mantissae have 53 bits, too much for Int# elim64# :: Int64# -> Int# -> (# Integer, Int# #) elim64# n e = - case zeroCount (toByte64# n) of + case zeroCount (int64ToInt# n) of t | isTrue# (e <=# t) -> (# integerFromInt64# (uncheckedIShiftRA64# n e), 0# #) | isTrue# (t <# 8#) -> (# integerFromInt64# (uncheckedIShiftRA64# n t), e -# t #) | otherwise -> elim64# (uncheckedIShiftRA64# n 8#) (e -# 8#) @@ -60,41 +57,13 @@ elimZerosInteger m e = elim64# (TO64 m) e elimZerosInt# :: Int# -> Int# -> (# Integer, Int# #) elimZerosInt# n e = - case zeroCount (toByte# n) of + case zeroCount n of t | isTrue# (e <=# t) -> (# IS (uncheckedIShiftRA# n e), 0# #) | isTrue# (t <# 8#) -> (# IS (uncheckedIShiftRA# n t), e -# t #) | otherwise -> elimZerosInt# (uncheckedIShiftRA# n 8#) (e -# 8#) -{-# INLINE zeroCount #-} +-- | Number of trailing zero bits in a byte zeroCount :: Int# -> Int# -zeroCount i = - case zeroCountArr of - BA ba -> indexInt8Array# ba i - -toByte# :: Int# -> Int# -toByte# i = word2Int# (and# 255## (int2Word# i)) - - -data BA = BA ByteArray# - --- Number of trailing zero bits in a byte -zeroCountArr :: BA -zeroCountArr = - let mkArr s = - case newByteArray# 256# s of - (# s1, mba #) -> - case writeInt8Array# mba 0# 8# s1 of - s2 -> - let fillA step val idx st - | isTrue# (idx <# 256#) = - case writeInt8Array# mba idx val st of - nx -> fillA step val (idx +# step) nx - | isTrue# (step <# 256#) = - fillA (2# *# step) (val +# 1#) step st - | otherwise = st - in case fillA 2# 0# 1# s2 of - s3 -> case unsafeFreezeByteArray# mba s3 of - (# _, ba #) -> ba - in case mkArr realWorld# of - b -> BA b - +zeroCount i = indexInt8OffAddr# arr (word2Int# (narrow8Word# (int2Word# i))) -- index must be in [0,255] + where + arr = "\8\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\4\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\5\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\4\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\6\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\4\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\5\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\4\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\7\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\4\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\5\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\4\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\6\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\4\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\5\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0\4\0\1\0\2\0\1\0\3\0\1\0\2\0\1\0"# |