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Diffstat (limited to 'libraries/ghc-bignum/src/GHC/Num/Primitives.hs')
| -rw-r--r-- | libraries/ghc-bignum/src/GHC/Num/Primitives.hs | 623 |
1 files changed, 623 insertions, 0 deletions
diff --git a/libraries/ghc-bignum/src/GHC/Num/Primitives.hs b/libraries/ghc-bignum/src/GHC/Num/Primitives.hs new file mode 100644 index 0000000000..2c1a0b6955 --- /dev/null +++ b/libraries/ghc-bignum/src/GHC/Num/Primitives.hs @@ -0,0 +1,623 @@ +{-# LANGUAGE CPP #-} +{-# LANGUAGE NoImplicitPrelude #-} +{-# LANGUAGE BangPatterns #-} +{-# LANGUAGE MagicHash #-} +{-# LANGUAGE UnboxedTuples #-} +{-# LANGUAGE UnliftedFFITypes #-} +{-# LANGUAGE NegativeLiterals #-} +{-# LANGUAGE ExplicitForAll #-} +{-# LANGUAGE FlexibleInstances #-} +{-# LANGUAGE RankNTypes #-} +{-# LANGUAGE ScopedTypeVariables #-} +{-# LANGUAGE BlockArguments #-} +{-# LANGUAGE BinaryLiterals #-} +{-# OPTIONS_GHC -fexpose-all-unfoldings #-} + +module GHC.Num.Primitives + ( + -- * Bool# + Bool# + , (&&#) + , (||#) + , notB# + -- * Int# + , testBitI# + , minI# + , maxI# + , sgnI# + , absI# + , cmpI# + , intEncodeDouble# + , popCntI# + -- * Word# + , andNot# + , cmpW# + , bitW# + , maxW# + , minW# + , testBitW# + , shiftRW# + , plusWord3# + , plusWord12# + , quotRemWord3# + , wordFromAbsInt# + , wordLog2# + , wordLogBase# + , wordSizeInBase# + , wordIsPowerOf2# + , wordEncodeDouble# + , wordReverseBits# + , wordReverseBits32# + , wordReverseBytes# + -- ** Addr import/export + , wordFromAddr# + , wordFromAddrLE# + , wordFromAddrBE# + , wordToAddr# + , wordToAddrLE# + , wordToAddrBE# + , wordWriteAddrLE# + , wordWriteAddrBE# + -- ** ByteArray import/export + , wordFromByteArray# + , wordFromByteArrayLE# + , wordFromByteArrayBE# + , wordToMutableByteArray# + , wordToMutableByteArrayLE# + , wordToMutableByteArrayBE# + , wordWriteMutableByteArrayLE# + , wordWriteMutableByteArrayBE# + -- * Exception + , underflow + , divByZero + , unexpectedValue + -- * IO + , ioWord# + , ioInt# + , ioVoid + , ioBool + ) +where + +#include "MachDeps.h" +#include "WordSize.h" + +-- Required for WORDS_BIGENDIAN +#include <ghcautoconf.h> + +#if (__GLASGOW_HASKELL__ < 811) +import GHC.Magic +#endif + +import GHC.Prim +import GHC.Types +import GHC.Tuple () -- See Note [Depend on GHC.Tuple] in GHC.Base + +default () + +---------------------------------- +-- Bool# +---------------------------------- + +type Bool# = Int# + +(&&#) :: Bool# -> Bool# -> Bool# +(&&#) = andI# + +(||#) :: Bool# -> Bool# -> Bool# +(||#) = orI# + +notB# :: Bool# -> Bool# +notB# x = x `xorI#` 1# + +infixr 3 &&# +infixr 2 ||# + + +---------------------------------- +-- Int# +---------------------------------- + +-- | Branchless `abs` +absI# :: Int# -> Int# +absI# i# = (i# `xorI#` nsign) -# nsign + where + -- nsign = negateInt# (i# <# 0#) + nsign = uncheckedIShiftRA# i# (WORD_SIZE_IN_BITS# -# 1#) + +-- | Branchless `signum` +sgnI# :: Int# -> Int# +sgnI# x# = (x# ># 0#) -# (x# <# 0#) + +-- | Population count +popCntI# :: Int# -> Word# +popCntI# i = popCnt# (int2Word# i) + +-- | Branchless comparison +cmpI# :: Int# -> Int# -> Int# +cmpI# x# y# = (x# ># y#) -# (x# <# y#) + +testBitI# :: Int# -> Word# -> Bool# +testBitI# x i = ((uncheckedIShiftL# 1# (word2Int# i)) `andI#` x) /=# 0# + +minI# :: Int# -> Int# -> Int# +minI# x y | isTrue# (x <=# y) = x + | True = y + +maxI# :: Int# -> Int# -> Int# +maxI# x y | isTrue# (x >=# y) = x + | True = y + +-- | Encode (# Int# mantissa, Int# exponent #) into a Double#. +-- +-- (provided by GHC's RTS) +foreign import ccall unsafe "__int_encodeDouble" + intEncodeDouble# :: Int# -> Int# -> Double# + +---------------------------------- +-- Word# +---------------------------------- + +andNot# :: Word# -> Word# -> Word# +andNot# x y = x `and#` (not# y) + +cmpW# :: Word# -> Word# -> Ordering +{-# INLINE cmpW# #-} +cmpW# x# y# + | isTrue# (x# `ltWord#` y#) = LT + | isTrue# (x# `eqWord#` y#) = EQ + | True = GT + +-- | Return the absolute value of the Int# in a Word# +wordFromAbsInt# :: Int# -> Word# +wordFromAbsInt# i + | isTrue# (i >=# 0#) = int2Word# i + | True = int2Word# (negateInt# i) + +minW# :: Word# -> Word# -> Word# +minW# x# y# | isTrue# (x# `leWord#` y#) = x# + | True = y# + +maxW# :: Word# -> Word# -> Word# +maxW# x# y# | isTrue# (x# `gtWord#` y#) = x# + | True = y# + +bitW# :: Int# -> Word# +bitW# k = 1## `uncheckedShiftL#` k + +testBitW# :: Word# -> Word# -> Bool# +testBitW# w k = w `and#` (1## `uncheckedShiftL#` word2Int# k) `neWord#` 0## + +-- | Safe right shift for Word# +shiftRW# :: Word# -> Word# -> Word# +shiftRW# a b + | isTrue# (b `geWord#` WORD_SIZE_IN_BITS##) = 0## + | True = a `uncheckedShiftRL#` (word2Int# b) + +-- | (h,l) <- a + (hb,lb) +plusWord12# :: Word# -> (# Word#,Word# #) -> (# Word#,Word# #) +{-# INLINABLE plusWord12# #-} +plusWord12# a0 (# b1,b0 #) = (# m1, m0 #) + where + !(# t, m0 #) = plusWord2# a0 b0 + !m1 = plusWord# t b1 + +-- | Add 3 values together +plusWord3# :: Word# -> Word# -> Word# -> (# Word#, Word# #) +{-# INLINABLE plusWord3# #-} +plusWord3# a b c = (# r1, r0 #) + where + !(# t1, t0 #) = plusWord2# a b + !(# t2, r0 #) = plusWord2# t0 c + !r1 = plusWord# t1 t2 + + +-- | 2-by-1 large division +-- +-- Requires: +-- b0 /= 0 +-- a1 >= b0 (not required, but if not q1=0) +quotRemWord3# :: (# Word#,Word# #) -> Word# -> (# (# Word#,Word# #),Word# #) +quotRemWord3# (# a1,a0 #) b0 = (# (# q1, q0 #), r0 #) + where + !(# q1, r' #) = quotRemWord# a1 b0 + !(# q0, r0 #) = quotRemWord2# r' a0 b0 + + + +-- | Encode (# Word# mantissa, Int# exponent #) into a Double#. +-- +-- (provided by GHC's RTS) +foreign import ccall unsafe "__word_encodeDouble" + wordEncodeDouble# :: Word# -> Int# -> Double# + +-- | Compute base-2 log of 'Word#' +-- +-- This is internally implemented as count-leading-zeros machine instruction. +wordLog2# :: Word# -> Word# +wordLog2# w = (WORD_SIZE_IN_BITS## `minusWord#` 1##) `minusWord#` (clz# w) + +-- | Logarithm for an arbitrary base +wordLogBase# :: Word# -> Word# -> Word# +wordLogBase# base a + | isTrue# (base `leWord#` 1##) + = case unexpectedValue of _ -> 0## + + | 2## <- base + = wordLog2# a + + | True + = case go base of (# _, e' #) -> e' + where + goSqr pw = case timesWord2# pw pw of + (# 0##, l #) -> go l + (# _ , _ #) -> (# a, 0## #) + go pw = if isTrue# (a `ltWord#` pw) + then (# a, 0## #) + else case goSqr pw of + (# q, e #) -> if isTrue# (q `ltWord#` pw) + then (# q, 2## `timesWord#` e #) + else (# q `quotWord#` pw + , 2## `timesWord#` e `plusWord#` 1## #) + +wordSizeInBase# :: Word# -> Word# -> Word# +wordSizeInBase# _ 0## = 0## +wordSizeInBase# base w = 1## `plusWord#` wordLogBase# base w + +-- | Indicate if the value is a power of two and which one +wordIsPowerOf2# :: Word# -> (# () | Word# #) +wordIsPowerOf2# w + | isTrue# (popCnt# w `neWord#` 1##) = (# () | #) + | True = (# | ctz# w #) + +-- | Reverse bytes in a Word# +wordReverseBytes# :: Word# -> Word# +wordReverseBytes# x0 = r + where +#if WORD_SIZE_IN_BITS == 64 + x1 = ((x0 `and#` 0x00FF00FF00FF00FF##) `uncheckedShiftL#` 8#) `or#` ((x0 `and#` 0xFF00FF00FF00FF00##) `uncheckedShiftRL#` 8#) + x2 = ((x1 `and#` 0x0000FFFF0000FFFF##) `uncheckedShiftL#` 16#) `or#` ((x1 `and#` 0xFFFF0000FFFF0000##) `uncheckedShiftRL#` 16#) + r = ((x2 `and#` 0x00000000FFFFFFFF##) `uncheckedShiftL#` 32#) `or#` ((x2 `and#` 0xFFFFFFFF00000000##) `uncheckedShiftRL#` 32#) +#else + x1 = ((x0 `and#` 0x00FF00FF##) `uncheckedShiftL#` 8#) `or#` ((x0 `and#` 0xFF00FF00##) `uncheckedShiftRL#` 8#) + r = ((x1 `and#` 0x0000FFFF##) `uncheckedShiftL#` 16#) `or#` ((x1 `and#` 0xFFFF0000##) `uncheckedShiftRL#` 16#) +#endif + + +-- | Reverse bits in a Word# +wordReverseBits# :: Word# -> Word# +wordReverseBits# x0 = r + where +#if WORD_SIZE_IN_BITS == 64 + x1 = ((x0 `and#` 0x5555555555555555##) `uncheckedShiftL#` 1#) `or#` ((x0 `and#` 0xAAAAAAAAAAAAAAAA##) `uncheckedShiftRL#` 1#) + x2 = ((x1 `and#` 0x3333333333333333##) `uncheckedShiftL#` 2#) `or#` ((x1 `and#` 0xCCCCCCCCCCCCCCCC##) `uncheckedShiftRL#` 2#) + x3 = ((x2 `and#` 0x0F0F0F0F0F0F0F0F##) `uncheckedShiftL#` 4#) `or#` ((x2 `and#` 0xF0F0F0F0F0F0F0F0##) `uncheckedShiftRL#` 4#) + x4 = ((x3 `and#` 0x00FF00FF00FF00FF##) `uncheckedShiftL#` 8#) `or#` ((x3 `and#` 0xFF00FF00FF00FF00##) `uncheckedShiftRL#` 8#) + x5 = ((x4 `and#` 0x0000FFFF0000FFFF##) `uncheckedShiftL#` 16#) `or#` ((x4 `and#` 0xFFFF0000FFFF0000##) `uncheckedShiftRL#` 16#) + r = ((x5 `and#` 0x00000000FFFFFFFF##) `uncheckedShiftL#` 32#) `or#` ((x5 `and#` 0xFFFFFFFF00000000##) `uncheckedShiftRL#` 32#) +#else + x1 = ((x0 `and#` 0x55555555##) `uncheckedShiftL#` 1#) `or#` ((x0 `and#` 0xAAAAAAAA##) `uncheckedShiftRL#` 1#) + x2 = ((x1 `and#` 0x33333333##) `uncheckedShiftL#` 2#) `or#` ((x1 `and#` 0xCCCCCCCC##) `uncheckedShiftRL#` 2#) + x3 = ((x2 `and#` 0x0F0F0F0F##) `uncheckedShiftL#` 4#) `or#` ((x2 `and#` 0xF0F0F0F0##) `uncheckedShiftRL#` 4#) + x4 = ((x3 `and#` 0x00FF00FF##) `uncheckedShiftL#` 8#) `or#` ((x3 `and#` 0xFF00FF00##) `uncheckedShiftRL#` 8#) + r = ((x4 `and#` 0x0000FFFF##) `uncheckedShiftL#` 16#) `or#` ((x4 `and#` 0xFFFF0000##) `uncheckedShiftRL#` 16#) +#endif + +-- | Reverse bits in the Word32 subwords composing a Word# +wordReverseBits32# :: Word# -> Word# +#if WORD_SIZE_IN_BITS == 64 +wordReverseBits32# x0 = r + where + x1 = ((x0 `and#` 0x5555555555555555##) `uncheckedShiftL#` 1#) `or#` ((x0 `and#` 0xAAAAAAAAAAAAAAAA##) `uncheckedShiftRL#` 1#) + x2 = ((x1 `and#` 0x3333333333333333##) `uncheckedShiftL#` 2#) `or#` ((x1 `and#` 0xCCCCCCCCCCCCCCCC##) `uncheckedShiftRL#` 2#) + x3 = ((x2 `and#` 0x0F0F0F0F0F0F0F0F##) `uncheckedShiftL#` 4#) `or#` ((x2 `and#` 0xF0F0F0F0F0F0F0F0##) `uncheckedShiftRL#` 4#) + x4 = ((x3 `and#` 0x00FF00FF00FF00FF##) `uncheckedShiftL#` 8#) `or#` ((x3 `and#` 0xFF00FF00FF00FF00##) `uncheckedShiftRL#` 8#) + r = ((x4 `and#` 0x0000FFFF0000FFFF##) `uncheckedShiftL#` 16#) `or#` ((x4 `and#` 0xFFFF0000FFFF0000##) `uncheckedShiftRL#` 16#) +#else +wordReverseBits32# x0 = wordReverseBits# x0 +#endif + + +-- | Write a Word to @/addr/@ in base-256 little-endian representation and +-- return the number of bytes written. +wordToAddrLE# :: Word# -> Addr# -> State# s -> (# State# s, Word# #) +wordToAddrLE# x addr = go x 0# + where + go w c s + | 0## <- w + = (# s, int2Word# c #) + + | True + = case writeWord8OffAddr# addr c (w `and#` 0xFF##) s of + s' -> go (w `uncheckedShiftRL#` 8#) (c +# 1#) s' + +-- | Write a Word to @/addr/@ in base-256 big-endian representation and +-- return the number of bytes written. +wordToAddrBE# :: Word# -> Addr# -> State# s -> (# State# s, Word# #) +wordToAddrBE# w addr = go 0# (WORD_SIZE_IN_BITS# -# clz) + where + !clz = word2Int# (clz# w `and#` (not# 0b0111##)) -- keep complete bytes + + go c sh s + | 0# <- sh + = (# s, int2Word# c #) + + | True + , w' <- (w `uncheckedShiftRL#` (sh -# 8#)) `and#` 0xFF## + = case writeWord8OffAddr# addr c w' s of + s' -> go (c +# 1#) (sh -# 8#) s' + +-- | Write a Word to @/addr/@ in base-256 representation and +-- return the number of bytes written. +-- +-- The endianness is selected with the Bool# parameter: write most significant +-- byte first (big-endian) if @1#@ or least significant byte first +-- (little-endian) if @0#@. +wordToAddr# :: Word# -> Addr# -> Bool# -> State# s -> (# State# s, Word# #) +wordToAddr# a addr 0# s = wordToAddrLE# a addr s +wordToAddr# a addr _ s = wordToAddrBE# a addr s + + +-- | Read a Word from @/addr/@ in base-256 little-endian representation. +-- +-- @'n' is the number of bytes to read. +wordFromAddrLE# :: Word# -> Addr# -> State# s -> (# State# s, Word# #) +wordFromAddrLE# n addr s + -- Optimize when we read a full word + | WORD_SIZE_IN_BYTES## <- n + = case readWordOffAddr# addr 0# s of +#if defined(WORDS_BIGENDIAN) + (# s', w #) -> (# s', wordReverseBytes# w #) +#else + (# s', w #) -> (# s', w #) +#endif + +wordFromAddrLE# n addr s0 = go 0## 0# s0 + where + go w c s + | isTrue# (c ==# word2Int# n) + = (# s, w #) + + | True + = case readWord8OffAddr# addr c s of + (# s', b #) -> go (w `or#` (b `uncheckedShiftL#` (c `uncheckedIShiftL#` 3#))) + (c +# 1#) + s' + +-- | Read a Word from @/addr/@ in base-256 big-endian representation. +-- +-- @'n' is the number of bytes to read. +wordFromAddrBE# :: Word# -> Addr# -> State# s -> (# State# s, Word# #) +wordFromAddrBE# n addr s + -- Optimize when we read a full word + | WORD_SIZE_IN_BYTES## <- n + = case readWordOffAddr# addr 0# s of +#if defined(WORDS_BIGENDIAN) + (# s', w #) -> (# s', w #) +#else + (# s', w #) -> (# s', wordReverseBytes# w #) +#endif + +wordFromAddrBE# n addr s0 = go 0## 0# s0 + where + go w c s + | isTrue# (c ==# word2Int# n) + = (# s, w #) + + | True + = case readWord8OffAddr# addr c s of + (# s', b #) -> go ((w `uncheckedShiftL#` 8#) `or#` b) + (c +# 1#) + s' + +-- | Read a Word from @/addr/@ in base-256 representation. +-- +-- @'n' is the number of bytes to read. +-- +-- The endianness is selected with the Bool# parameter: write most significant +-- byte first (big-endian) if @1#@ or least significant byte first +-- (little-endian) if @0#@. +wordFromAddr# :: Word# -> Addr# -> Bool# -> State# s -> (# State# s, Word# #) +wordFromAddr# a addr 0# s = wordFromAddrLE# a addr s +wordFromAddr# a addr _ s = wordFromAddrBE# a addr s + + + +-- | Write a full word with little-endian encoding +wordWriteAddrLE# :: Word# -> Addr# -> State# s -> State# s +wordWriteAddrLE# w addr = writeWordOffAddr# addr 0# +#if defined(WORDS_BIGENDIAN) + (wordReverseBytes# w) +#else + w +#endif + +-- | Write a full word with little-endian encoding +wordWriteAddrBE# :: Word# -> Addr# -> State# s -> State# s +wordWriteAddrBE# w addr = writeWordOffAddr# addr 0# +#if defined(WORDS_BIGENDIAN) + w +#else + (wordReverseBytes# w) +#endif + +-- | Write a Word to @/MutableByteArray/@ in base-256 little-endian +-- representation and return the number of bytes written. +-- +-- The offset is in bytes. +wordToMutableByteArrayLE# :: Word# -> MutableByteArray# s -> Word# -> State# s -> (# State# s, Word# #) +wordToMutableByteArrayLE# x mba off = go x 0# + where + go w c s + | 0## <- w + = (# s, int2Word# c #) + + | True + = case writeWord8Array# mba (word2Int# off +# c) (w `and#` 0xFF##) s of + s' -> go (w `uncheckedShiftRL#` 8#) (c +# 1#) s' + +-- | Write a Word to @/MutableByteArray/@ in base-256 big-endian representation and +-- return the number of bytes written. +-- +-- The offset is in bytes. +wordToMutableByteArrayBE# :: Word# -> MutableByteArray# s -> Word# -> State# s -> (# State# s, Word# #) +wordToMutableByteArrayBE# w mba off = go 0# (WORD_SIZE_IN_BITS# -# clz) + where + !clz = word2Int# (clz# w `and#` (not# 0b0111##)) -- keep complete bytes + + go c sh s + | 0# <- sh + = (# s, int2Word# c #) + + | True + , w' <- (w `uncheckedShiftRL#` (sh -# 8#)) `and#` 0xFF## + = case writeWord8Array# mba (word2Int# off +# c) w' s of + s' -> go (c +# 1#) (sh -# 8#) s' + +-- | Write a Word to @/MutableByteArray/@ in base-256 representation and +-- return the number of bytes written. +-- +-- The endianness is selected with the Bool# parameter: write most significant +-- byte first (big-endian) if @1#@ or least significant byte first +-- (little-endian) if @0#@. +-- +-- The offset is in bytes. +wordToMutableByteArray# :: Word# -> MutableByteArray# s -> Word# -> Bool# -> State# s -> (# State# s, Word# #) +wordToMutableByteArray# a mba off 0# s = wordToMutableByteArrayLE# a mba off s +wordToMutableByteArray# a mba off _ s = wordToMutableByteArrayBE# a mba off s + +-- | Write a full word with little-endian encoding +wordWriteMutableByteArrayLE# :: Word# -> MutableByteArray# s -> Word# -> State# s -> State# s +wordWriteMutableByteArrayLE# w mba off = writeWord8ArrayAsWord# mba (word2Int# off) +#if defined(WORDS_BIGENDIAN) + (wordReverseBytes# w) +#else + w +#endif + +-- | Write a full word with little-endian encoding +wordWriteMutableByteArrayBE# :: Word# -> MutableByteArray# s -> Word# -> State# s -> State# s +wordWriteMutableByteArrayBE# w mba off = writeWord8ArrayAsWord# mba (word2Int# off) +#if defined(WORDS_BIGENDIAN) + w +#else + (wordReverseBytes# w) +#endif + +-- | Read a Word from @/ByteArray/@ in base-256 little-endian representation. +-- +-- @'n' is the number of bytes to read. +wordFromByteArrayLE# :: Word# -> ByteArray# -> Word# -> Word# +wordFromByteArrayLE# n ba off = + case n of + -- Optimize when we read a full word + WORD_SIZE_IN_BYTES## -> case indexWord8ArrayAsWord# ba (word2Int# off) of +#if defined(WORDS_BIGENDIAN) + w -> wordReverseBytes# w +#else + w -> w +#endif + + _ -> let + go w c + | isTrue# (c ==# word2Int# n) + = w + + | True + = case indexWord8Array# ba (word2Int# off +# c) of + b -> go (w `or#` (b `uncheckedShiftL#` (c `uncheckedIShiftL#` 3#))) + (c +# 1#) + in go 0## 0# + +-- | Read a Word from @/ByteArray/@ in base-256 big-endian representation. +-- +-- @'n' is the number of bytes to read. +wordFromByteArrayBE# :: Word# -> ByteArray# -> Word# -> Word# +wordFromByteArrayBE# n ba off + -- Optimize when we read a full word + | WORD_SIZE_IN_BYTES## <- n + = case indexWord8ArrayAsWord# ba (word2Int# off) of +#if defined(WORDS_BIGENDIAN) + w -> w +#else + w -> wordReverseBytes# w +#endif + +wordFromByteArrayBE# n ba off = go 0## 0# + where + go w c + | isTrue# (c ==# word2Int# n) + = w + + | True + = case indexWord8Array# ba (word2Int# off +# c) of + b -> go ((w `uncheckedShiftL#` 8#) `or#` b) (c +# 1#) + +-- | Read a Word from @/ByteArray/@ in base-256 representation. +-- +-- @'n' is the number of bytes to read. +-- +-- The endianness is selected with the Bool# parameter: write most significant +-- byte first (big-endian) if @1#@ or least significant byte first +-- (little-endian) if @0#@. +wordFromByteArray# :: Word# -> ByteArray# -> Word# -> Bool# -> Word# +wordFromByteArray# a ba off 0# = wordFromByteArrayLE# a ba off +wordFromByteArray# a ba off _ = wordFromByteArrayBE# a ba off + +---------------------------------- +-- IO +---------------------------------- + +ioVoid :: IO a -> State# RealWorld -> State# RealWorld +ioVoid (IO io) s = case io s of + (# s', _ #) -> s' + +ioWord# :: IO Word -> State# RealWorld -> (# State# RealWorld, Word# #) +ioWord# (IO io) s = case io s of + (# s', W# w #) -> (# s', w #) + +ioInt# :: IO Int -> State# RealWorld -> (# State# RealWorld, Int# #) +ioInt# (IO io) s = case io s of + (# s', I# i #) -> (# s', i #) + +ioBool :: IO Bool -> State# RealWorld -> (# State# RealWorld, Bool# #) +ioBool (IO io) s = case io s of + (# s', False #) -> (# s', 0# #) + (# s', True #) -> (# s', 1# #) + + +---------------------------------- +-- Exception +---------------------------------- + +#if (__GLASGOW_HASKELL__ >= 811) + +underflow :: a +underflow = raiseUnderflow# void# + +divByZero :: a +divByZero = raiseDivZero# void# + +unexpectedValue :: a +unexpectedValue = raiseOverflow# void# + +#else + +-- Before GHC 8.11 we use the exception trick taken from #14664 +exception :: a +exception = runRW# \s -> + case atomicLoop s of + (# _, a #) -> a + where + atomicLoop s = atomically# atomicLoop s + +underflow :: a +underflow = exception + +divByZero :: a +divByZero = exception + +unexpectedValue :: a +unexpectedValue = exception + +#endif |