40 lines
1.0 KiB
Haskell
40 lines
1.0 KiB
Haskell
-- |
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-- Module : Crypto.Internal.Compat
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-- License : BSD-style
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-- Maintainer : Vincent Hanquez <vincent@snarc.org>
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-- Stability : stable
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-- Portability : Good
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--
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-- This module try to keep all the difference between versions of base
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-- or other needed packages, so that modules don't need to use CPP
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--
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{-# LANGUAGE CPP #-}
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module Crypto.Internal.Compat
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( unsafeDoIO
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, popCount
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) where
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import System.IO.Unsafe
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#if MIN_VERSION_base(4,5,0)
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import Data.Bits (popCount)
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#endif
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-- | perform io for hashes that do allocation and ffi.
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-- unsafeDupablePerformIO is used when possible as the
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-- computation is pure and the output is directly linked
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-- to the input. we also do not modify anything after it has
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-- been returned to the user.
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unsafeDoIO :: IO a -> a
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#if __GLASGOW_HASKELL__ > 704
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unsafeDoIO = unsafeDupablePerformIO
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#else
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unsafeDoIO = unsafePerformIO
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#endif
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#if !(MIN_VERSION_base(4,5,0))
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popCount :: Word64 -> Int
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popCount n = loop 0 n
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where loop c 0 = c
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loop c i = loop (c + if testBit c 0 then 1 else 0) (i `shiftR` 1)
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#endif
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