diff --git a/README b/README deleted file mode 100644 --- a/README +++ /dev/null @@ -1,45 +0,0 @@ -Efficient, general purpose pseudo-random number generation ----------------------------------------------------------- - -This package provides the System.Random.MWC module, a Haskell library -for generating high-quality pseudo-random numbers in a space- and -time-efficient way. - - -Performance ------------ - -This library has been carefully optimised for high performance. To -obtain the best runtime efficiency, it is imperative to compile -libraries and applications that use this library using a high level of -optimisation. - -Suggested GHC options: - - -O -fvia-C -funbox-strict-fields - -To illustrate, here are the times (in seconds) to generate and sum 250 -million random Word32 values, on a laptop with a 2.4GHz Core2 Duo -P8600 processor, running Fedora 11 and GHC 6.10.3: - - no flags 200+ - -O 1.249 - -O -fvia-C 0.991 - -As the numbers above suggest, compiling without optimisation will -yield unacceptable performance. - - -Get involved! -------------- - -Please feel welcome to contribute new code or bug fixes. You can -fetch the source repository from here: - -http://bitbucket.org/bos/mwc-random - - -Authors -------- - -Bryan O'Sullivan diff --git a/README.markdown b/README.markdown new file mode 100644 --- /dev/null +++ b/README.markdown @@ -0,0 +1,50 @@ +# Efficient, general purpose pseudo-random number generation + +This package provides the System.Random.MWC module, a Haskell library +for generating high-quality pseudo-random numbers in a space- and +time-efficient way. + + +# Performance + +This library has been carefully optimised for high performance. To +obtain the best runtime efficiency, it is imperative to compile +libraries and applications that use this library using a high level of +optimisation. + +Suggested GHC options: + + -O -fvia-C -funbox-strict-fields + +To illustrate, here are the times (in seconds) to generate and sum 250 +million random Word32 values, on a laptop with a 2.4GHz Core2 Duo +P8600 processor, running Fedora 11 and GHC 6.10.3: + + no flags 200+ + -O 1.249 + -O -fvia-C 0.991 + +As the numbers above suggest, compiling without optimisation will +yield unacceptable performance. + + +# Get involved! + +Please report bugs via the +[bitbucket issue tracker](http://bitbucket.org/bos/mwc-random). + +Master [Mercurial repository](http://bitbucket.org/bos/mwc-random): + +* `hg clone http://bitbucket.org/bos/mwc-random` + +There's also a [git mirror](http://github.com/bos/mwc-random): + +* `git clone git://github.com/bos/mwc-random.git` + +(You can create and contribute changes using either Mercurial or git.) + + +# Authors + +This library is written and maintained by Bryan O'Sullivan, +. diff --git a/System/Random/MWC.hs b/System/Random/MWC.hs --- a/System/Random/MWC.hs +++ b/System/Random/MWC.hs @@ -238,8 +238,8 @@ {-# INLINE uniformR #-} wordsTo64Bit :: Integral a => Word32 -> Word32 -> a -wordsTo64Bit a b = - fromIntegral ((fromIntegral a `shiftL` 32) .|. fromIntegral b) +wordsTo64Bit x y = + fromIntegral ((fromIntegral x `shiftL` 32) .|. fromIntegral y) {-# INLINE wordsTo64Bit #-} wordToBool :: Word32 -> Bool @@ -254,13 +254,13 @@ {-# INLINE wordToFloat #-} wordsToDouble :: Word32 -> Word32 -> Double -wordsToDouble x y = (fromIntegral a * m_inv_32 + (0.5 + m_inv_53) + - fromIntegral (b .&. 0xFFFFF) * m_inv_52) +wordsToDouble x y = (fromIntegral u * m_inv_32 + (0.5 + m_inv_53) + + fromIntegral (v .&. 0xFFFFF) * m_inv_52) where m_inv_52 = 2.220446049250313080847263336181640625e-16 m_inv_53 = 1.1102230246251565404236316680908203125e-16 m_inv_32 = 2.3283064365386962890625e-10 - a = fromIntegral x :: Int32 - b = fromIntegral y :: Int32 + u = fromIntegral x :: Int32 + v = fromIntegral y :: Int32 {-# INLINE wordsToDouble #-} -- | State of the pseudo-random number generator. @@ -393,18 +393,26 @@ nextIndex i = fromIntegral j where j = fromIntegral (i+1) :: Word8 +a :: Word64 +a = 1540315826 + uniformWord32 :: PrimMonad m => Gen (PrimState m) -> m Word32 uniformWord32 (Gen q) = do - let a = 809430660 :: Word64 i <- nextIndex `liftM` M.unsafeRead q ioff c <- fromIntegral `liftM` M.unsafeRead q coff qi <- fromIntegral `liftM` M.unsafeRead q i - let t = a * qi + c - t32 = fromIntegral t - M.unsafeWrite q i t32 + let t = a * qi + c + c' = fromIntegral (t `shiftR` 32) + x = fromIntegral t + c' + x_lt_c = x < c' + x' | x_lt_c = x + 1 + | otherwise = x + c'' | x_lt_c = c' + 1 + | otherwise = c' + M.unsafeWrite q i x' M.unsafeWrite q ioff (fromIntegral i) - M.unsafeWrite q coff (fromIntegral (t `shiftR` 32)) - return t32 + M.unsafeWrite q coff (fromIntegral c'') + return x' {-# INLINE uniformWord32 #-} uniform1 :: PrimMonad m => (Word32 -> a) -> Gen (PrimState m) -> m a @@ -415,22 +423,32 @@ uniform2 :: PrimMonad m => (Word32 -> Word32 -> a) -> Gen (PrimState m) -> m a uniform2 f (Gen q) = do - let a = 809430660 :: Word64 i <- nextIndex `liftM` M.unsafeRead q ioff let j = nextIndex i c <- fromIntegral `liftM` M.unsafeRead q coff qi <- fromIntegral `liftM` M.unsafeRead q i qj <- fromIntegral `liftM` M.unsafeRead q j let t = a * qi + c - t32 = fromIntegral t - c' = t `shiftR` 32 - u = a * qj + c' - u32 = fromIntegral u - M.unsafeWrite q i t32 - M.unsafeWrite q j u32 + c' = fromIntegral (t `shiftR` 32) + x = fromIntegral t + c' + x_lt_c = x < c' + x' | x_lt_c = x + 1 + | otherwise = x + c'' | x_lt_c = c' + 1 + | otherwise = c' + u = a * qj + fromIntegral c'' + d' = fromIntegral (u `shiftR` 32) + y = fromIntegral u + d' + y_lt_d = y < d' + y' | y_lt_d = y + 1 + | otherwise = y + d'' | y_lt_d = d' + 1 + | otherwise = d' + M.unsafeWrite q i x' + M.unsafeWrite q j y' M.unsafeWrite q ioff (fromIntegral j) - M.unsafeWrite q coff (fromIntegral (u `shiftR` 32)) - return $! f t32 u32 + M.unsafeWrite q coff (fromIntegral d'') + return $! f x' y' {-# INLINE uniform2 #-} -- Type family for fixed size integrals. For signed data types it's diff --git a/mwc-random.cabal b/mwc-random.cabal --- a/mwc-random.cabal +++ b/mwc-random.cabal @@ -1,5 +1,5 @@ name: mwc-random -version: 0.8.0.2 +version: 0.8.0.3 synopsis: Fast, high quality pseudo random number generation description: This package contains code for generating high quality random @@ -25,7 +25,7 @@ build-type: Simple cabal-version: >= 1.6 extra-source-files: - README + README.markdown benchmarks/Benchmark.hs benchmarks/Quickie.hs