85 lines
2.2 KiB
Haskell
85 lines
2.2 KiB
Haskell
-- |
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-- Module : Data.Memory.Internal.CompatPrim
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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 : Compat
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--
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-- This module try to keep all the difference between versions of ghc primitive
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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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-- Note that MagicHash and CPP conflicts in places, making it "more interesting"
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-- to write compat code for primitives
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--
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{-# LANGUAGE CPP #-}
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{-# LANGUAGE BangPatterns #-}
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{-# LANGUAGE MagicHash #-}
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{-# LANGUAGE UnboxedTuples #-}
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module Data.Memory.Internal.CompatPrim
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( be32Prim
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, le32Prim
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, byteswap32Prim
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, booleanPrim
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, eitherDivideBy8#
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) where
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import GHC.Prim
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-- | byteswap Word# to or from Big Endian
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--
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-- on a big endian machine, this function is a nop.
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be32Prim :: Word# -> Word#
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#ifdef ARCH_IS_LITTLE_ENDIAN
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be32Prim = byteswap32Prim
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#else
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be32Prim w = w
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#endif
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-- | byteswap Word# to or from Little Endian
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--
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-- on a little endian machine, this function is a nop.
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le32Prim :: Word# -> Word#
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#ifdef ARCH_IS_LITTLE_ENDIAN
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le32Prim w = w
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#else
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le32Prim = byteswap32Prim
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#endif
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byteswap32Prim :: Word# -> Word#
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#if __GLASGOW_HASKELL__ >= 708
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byteswap32Prim w = byteSwap32# w
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#else
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byteswap32Prim w =
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let !a = uncheckedShiftL# w 24#
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!b = and# (uncheckedShiftL# w 8#) 0x00ff0000##
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!c = and# (uncheckedShiftRL# w 8#) 0x0000ff00##
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!d = and# (uncheckedShiftRL# w 24#) 0x000000ff##
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in or# a (or# b (or# c d))
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#endif
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#if __GLASGOW_HASKELL__ >= 708
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booleanPrim :: Int# -> Bool
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booleanPrim v = tagToEnum# v
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#else
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booleanPrim :: Bool -> Bool
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booleanPrim b = b
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#endif
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-- | Apply or or another function if 8 divides the number of bytes
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eitherDivideBy8# :: Int# -- ^ number of bytes
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-> (Int# -> a) -- ^ if it divided by 8, the argument is the number of 8 bytes words
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-> (Int# -> a) -- ^ if it doesn't, just the number of bytes
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-> a
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#if __GLASGOW_HASKELL__ >= 740
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eitherDivideBy8# v f8 f1 =
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let !(# q, r #) = quotRemInt v 8#
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in if booleanPrim (r ==# 0)
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then f8 q
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else f1 v
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#else
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eitherDivideBy8# v f8 f1 =
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if booleanPrim ((remInt# v 8#) ==# 0#)
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then f8 (quotInt# v 8#)
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else f1 v
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#endif
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