aligned-foreignptr (empty) → 0.1

raw patch · 4 files changed

+159/−0 lines, 4 filesdep +basesetup-changed

Dependencies added: base

Files

• Foreign/ForeignPtr/Aligned.hs +92/−0
• LICENSE +32/−0
• Setup.hs +5/−0
• aligned-foreignptr.cabal +30/−0

@@ -0,0 +1,92 @@++-- | A properly aligned ForeignPtr type.+-- This can be currently achieved only by wasting some bytes.++module Foreign.ForeignPtr.Aligned +  ( AlignedForeignPtr +  , Alignment, align, fromAlignment+  , mallocAlignedForeignPtr+  , mallocAlignedForeignPtrArray+  , mallocAlignedForeignPtrBytes+  , withAlignedForeignPtr+  , finalizeAlignedForeignPtr+  , touchAlignedForeignPtr+  , castAlignedForeignPtr+  ) +  where++--------------------------------------------------------------------------------++import Data.Bits+import Foreign.Ptr+import Foreign.ForeignPtr+import Foreign.Storable+import System.IO.Unsafe++--------------------------------------------------------------------------------++-- | Should be a power of two.+newtype Alignment = Alignment { fromAlignment :: Int } deriving Show++isPowerOfTwo :: Int -> Bool+isPowerOfTwo k +  | k< 1 = False+  | k==1 = True+  | True = if odd k +      then False+      else isPowerOfTwo (k `div` 2)++-- | A \"smart\" constructor which checks whether the input +-- is a power of two.+align :: Int -> Alignment+align k = if isPowerOfTwo k +  then Alignment k+  else error "invalid alignment"++-- | The aligned ForeignPtr type+data AlignedForeignPtr a = AFPtr+  { _fptr   :: {-# UNPACK #-} !(ForeignPtr a)+  , _offset :: {-# UNPACK #-} !Int+  } + +instance Show (AlignedForeignPtr a) where+  show afptr = unsafePerformIO $ withAlignedForeignPtr afptr $ \p -> return (show p)+  +mallocAlignedForeignPtr :: Storable a => Alignment -> IO (AlignedForeignPtr a)+mallocAlignedForeignPtr align = mallocAlignedForeignPtrArray align 1+  +mallocAlignedForeignPtrArray :: Storable a => Alignment -> Int -> IO (AlignedForeignPtr a)+mallocAlignedForeignPtrArray align n = worker where+  worker = mallocAlignedForeignPtrBytes align (n * sizeOf undef)+  undef = ioAFPtrUndefined worker ++-- | This is here only to avoid the @ScopedTypeVariables@ language extension+-- for more portability.+ioAFPtrUndefined :: IO (AlignedForeignPtr a) -> a+ioAFPtrUndefined _ = undefined++mallocAlignedForeignPtrBytes :: Alignment -> Int -> IO (AlignedForeignPtr a)+mallocAlignedForeignPtrBytes (Alignment align) n = do+  fptr <- mallocForeignPtrBytes (n+align)    -- (n+align-1) would be enough, to be precise. But usually that's an odd number.+  ofs <- withForeignPtr fptr $ \p -> do+    let j = ptrToIntPtr p+        a = fromIntegral align :: IntPtr+        k = (j+a-1) .&. (complement (a-1))+    return $ fromIntegral (k-j)+  return (AFPtr fptr ofs)  ++withAlignedForeignPtr :: AlignedForeignPtr a -> (Ptr a -> IO b) -> IO b+withAlignedForeignPtr (AFPtr fptr ofs) action = +  withForeignPtr fptr $ \p -> action (p `plusPtr` ofs)++finalizeAlignedForeignPtr :: AlignedForeignPtr a -> IO ()+finalizeAlignedForeignPtr (AFPtr fptr ofs) = finalizeForeignPtr fptr++touchAlignedForeignPtr :: AlignedForeignPtr a -> IO ()+touchAlignedForeignPtr (AFPtr fptr ofs) = touchForeignPtr fptr++castAlignedForeignPtr :: AlignedForeignPtr a -> AlignedForeignPtr b+castAlignedForeignPtr (AFPtr fptr ofs) = AFPtr (castForeignPtr fptr) ofs++--------------------------------------------------------------------------------+

@@ -0,0 +1,32 @@+http://creativecommons.org/licenses/publicdomain/+-------------------------------------------------++Copyright-Only Dedication (based on United States law) or +Public Domain Certification++The person or persons who have associated work with this document (the +"Dedicator" or "Certifier") hereby either (a) certifies that, to the best of +his knowledge, the work of authorship identified is in the public domain +of the country from which the work is published, or (b) hereby dedicates +whatever copyright the dedicators holds in the work of authorship identified +below (the "Work") to the public domain. A certifier, moreover, dedicates any +copyright interest he may have in the associated work, and for these purposes, +is described as a "dedicator" below.++A certifier has taken reasonable steps to verify the copyright status of this +work. Certifier recognizes that his good faith efforts may not shield him +from liability if in fact the work certified is not in the public domain.++Dedicator makes this dedication for the benefit of the public at large and +to the detriment of the Dedicator's heirs and successors. Dedicator intends +this dedication to be an overt act of relinquishment in perpetuity of all +present and future rights under copyright law, whether vested or contingent, +in the Work. Dedicator understands that such relinquishment of all rights +includes the relinquishment of all rights to enforce (by lawsuit or otherwise) +those copyrights in the Work.++Dedicator recognizes that, once placed in the public domain, the Work may +be freely reproduced, distributed, transmitted, used, modified, built upon, +or otherwise exploited by anyone for any purpose, commercial or non-commercial, +and in any way, including by methods that have not yet been invented or +conceived.

@@ -0,0 +1,5 @@+#! /usr/bin/env runhaskell+ +import Distribution.Simple+main = defaultMain+

@@ -0,0 +1,30 @@+Name:                aligned-foreignptr+Version:             0.1+Synopsis:            An aligned ForeignPtr type+Description:         An aligned ForeignPtr type.+License:             PublicDomain+License-file:        LICENSE+Author:              Balazs Komuves+Maintainer:          bkomuves (plus) hackage (at) gmail (dot) com+Homepage:            http://code.haskell.org/~bkomuves/+Stability:           Experimental+Category:            System, Foreign+Tested-With:         GHC == 6.10.1 +Cabal-Version:       >= 1.2+Build-Type:          Simple++Flag base4+  Description: Base v4 ++Library+  if flag(base4)+    Build-Depends:        base >= 4 && < 5+    cpp-options:          -DBASE_MAJOR_VERSION=4+  else+    Build-Depends:        base >= 3 && < 4+    cpp-options:          -DBASE_MAJOR_VERSION=3+    +  Exposed-Modules:     Foreign.ForeignPtr.Aligned+  +  Hs-Source-Dirs:      .+  Extensions:          ForeignFunctionInterface