106 lines
3.5 KiB
Haskell
106 lines
3.5 KiB
Haskell
-- |
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-- Module : Data.Memory.Hash.FNV
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-- License : BSD-style
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-- Maintainer : Vincent Hanquez <vincent@snarc.org>
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-- Stability : experimental
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-- Portability : good
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--
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-- Fowler Noll Vo Hash (1 and 1a / 32 / 64 bits versions)
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-- <http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function>
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--
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{-# LANGUAGE GeneralizedNewtypeDeriving #-}
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{-# LANGUAGE MagicHash #-}
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{-# LANGUAGE UnboxedTuples #-}
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{-# LANGUAGE BangPatterns #-}
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module Data.Memory.Hash.FNV
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(
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-- * types
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FnvHash32(..)
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, FnvHash64(..)
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-- * methods
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, fnv1
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, fnv1a
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, fnv1_64
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, fnv1a_64
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) where
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import Basement.Bits
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import Basement.IntegralConv
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import Data.Memory.Internal.Compat ()
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import Data.Memory.Internal.Imports
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import GHC.Word
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import GHC.Prim hiding (Word64#, Int64#)
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import GHC.Types
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import GHC.Ptr
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-- | FNV1(a) hash (32 bit variants)
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newtype FnvHash32 = FnvHash32 Word32
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deriving (Show,Eq,Ord,NFData)
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-- | FNV1(a) hash (64 bit variants)
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newtype FnvHash64 = FnvHash64 Word64
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deriving (Show,Eq,Ord,NFData)
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fnv1_32_Mix8 :: Word8 -> FnvHash32 -> FnvHash32
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fnv1_32_Mix8 !w (FnvHash32 acc) = FnvHash32 ((0x01000193 * acc) .^. integralUpsize w)
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{-# INLINE fnv1_32_Mix8 #-}
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fnv1a_32_Mix8 :: Word8 -> FnvHash32 -> FnvHash32
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fnv1a_32_Mix8 !w (FnvHash32 acc) = FnvHash32 (0x01000193 * (acc .^. integralUpsize w))
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{-# INLINE fnv1a_32_Mix8 #-}
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fnv1_64_Mix8 :: Word8 -> FnvHash64 -> FnvHash64
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fnv1_64_Mix8 !w (FnvHash64 acc) = FnvHash64 ((0x100000001b3 * acc) .^. integralUpsize w)
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{-# INLINE fnv1_64_Mix8 #-}
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fnv1a_64_Mix8 :: Word8 -> FnvHash64 -> FnvHash64
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fnv1a_64_Mix8 !w (FnvHash64 acc) = FnvHash64 (0x100000001b3 * (acc .^. integralUpsize w))
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{-# INLINE fnv1a_64_Mix8 #-}
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-- | compute FNV1 (32 bit variant) of a raw piece of memory
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fnv1 :: Ptr Word8 -> Int -> IO FnvHash32
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fnv1 (Ptr addr) n = loop (FnvHash32 0x811c9dc5) 0
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where
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loop :: FnvHash32 -> Int -> IO FnvHash32
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loop !acc !i
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| i == n = pure $ acc
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| otherwise = do
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v <- read8 addr i
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loop (fnv1_32_Mix8 v acc) (i + 1)
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-- | compute FNV1a (32 bit variant) of a raw piece of memory
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fnv1a :: Ptr Word8 -> Int -> IO FnvHash32
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fnv1a (Ptr addr) n = loop (FnvHash32 0x811c9dc5) 0
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where
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loop :: FnvHash32 -> Int -> IO FnvHash32
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loop !acc !i
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| i == n = pure $ acc
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| otherwise = do
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v <- read8 addr i
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loop (fnv1a_32_Mix8 v acc) (i + 1)
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-- | compute FNV1 (64 bit variant) of a raw piece of memory
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fnv1_64 :: Ptr Word8 -> Int -> IO FnvHash64
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fnv1_64 (Ptr addr) n = loop (FnvHash64 0xcbf29ce484222325) 0
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where
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loop :: FnvHash64 -> Int -> IO FnvHash64
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loop !acc !i
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| i == n = pure $ acc
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| otherwise = do
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v <- read8 addr i
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loop (fnv1_64_Mix8 v acc) (i + 1)
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-- | compute FNV1a (64 bit variant) of a raw piece of memory
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fnv1a_64 :: Ptr Word8 -> Int -> IO FnvHash64
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fnv1a_64 (Ptr addr) n = loop (FnvHash64 0xcbf29ce484222325) 0
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where
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loop :: FnvHash64 -> Int -> IO FnvHash64
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loop !acc !i
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| i == n = pure $ acc
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| otherwise = do
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v <- read8 addr i
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loop (fnv1a_64_Mix8 v acc) (i + 1)
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read8 :: Addr# -> Int -> IO Word8
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read8 addr (I# i) = IO $ \s -> case readWord8OffAddr# addr i s of
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(# s2, e #) -> (# s2, W8# e #)
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