Initial import

This contains only the CV module. For version 
history of this module and it's siblings, contact
ville.e.t.tirronen@jyu.fi.

C2HS.hs

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+--  C->Haskell Compiler: Marshalling library
+--
+--  Copyright (c) [1999...2005] Manuel M T Chakravarty
+--
+--  Redistribution and use in source and binary forms, with or without
+--  modification, are permitted provided that the following conditions are met:
+-- 
+--  1. Redistributions of source code must retain the above copyright notice,
+--     this list of conditions and the following disclaimer. 
+--  2. Redistributions in binary form must reproduce the above copyright
+--     notice, this list of conditions and the following disclaimer in the
+--     documentation and/or other materials provided with the distribution. 
+--  3. The name of the author may not be used to endorse or promote products
+--     derived from this software without specific prior written permission. 
+--
+--  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+--  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+--  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
+--  NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
+--  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+--  TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+--  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+--  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+--  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+--  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+--
+--- Description ---------------------------------------------------------------
+--
+--  Language: Haskell 98
+--
+--  This module provides the marshaling routines for Haskell files produced by 
+--  C->Haskell for binding to C library interfaces.  It exports all of the
+--  low-level FFI (language-independent plus the C-specific parts) together
+--  with the C->HS-specific higher-level marshalling routines.
+--
+
+module C2HS (
+
+  -- * Re-export the language-independent component of the FFI 
+  module Foreign,
+
+  -- * Re-export the C language component of the FFI
+  module CForeign,
+
+  -- * Composite marshalling functions
+  withCStringLenIntConv, peekCStringLenIntConv, withIntConv, withFloatConv,
+  peekIntConv, peekFloatConv, withBool, peekBool, withEnum, peekEnum,
+
+  -- * Conditional results using 'Maybe'
+  nothingIf, nothingIfNull,
+
+  -- * Bit masks
+  combineBitMasks, containsBitMask, extractBitMasks,
+
+  -- * Conversion between C and Haskell types
+  cIntConv, cFloatConv, cToBool, cFromBool, cToEnum, cFromEnum
+) where 
+
+
+import Foreign
+       hiding       (Word)
+		    -- Should also hide the Foreign.Marshal.Pool exports in
+		    -- compilers that export them
+import CForeign
+
+import Monad        (when, liftM)
+
+
+-- Composite marshalling functions
+-- -------------------------------
+
+-- Strings with explicit length
+--
+withCStringLenIntConv s f    = withCStringLen s $ \(p, n) -> f (p, cIntConv n)
+peekCStringLenIntConv (s, n) = peekCStringLen (s, cIntConv n)
+
+-- Marshalling of numerals
+--
+
+withIntConv   :: (Storable b, Integral a, Integral b) 
+	      => a -> (Ptr b -> IO c) -> IO c
+withIntConv    = with. cIntConv
+
+withFloatConv :: (Storable b, RealFloat a, RealFloat b) 
+	      => a -> (Ptr b -> IO c) -> IO c
+withFloatConv  = with . cFloatConv
+
+peekIntConv   :: (Storable a, Integral a, Integral b) 
+	      => Ptr a -> IO b
+peekIntConv    = liftM cIntConv . peek
+
+peekFloatConv :: (Storable a, RealFloat a, RealFloat b) 
+	      => Ptr a -> IO b
+peekFloatConv  = liftM cFloatConv . peek
+
+-- Passing Booleans by reference
+--
+
+withBool :: (Integral a, Storable a) => Bool -> (Ptr a -> IO b) -> IO b
+withBool  = with . fromBool
+
+peekBool :: (Integral a, Storable a) => Ptr a -> IO Bool
+peekBool  = liftM toBool . peek
+
+
+-- Passing enums by reference
+--
+
+withEnum :: (Enum a, Integral b, Storable b) => a -> (Ptr b -> IO c) -> IO c
+withEnum  = with. cFromEnum
+
+peekEnum :: (Enum a, Integral b, Storable b) => Ptr b -> IO a
+peekEnum  = liftM cToEnum . peek
+
+
+-- Storing of 'Maybe' values
+-- -------------------------
+
+instance Storable a => Storable (Maybe a) where
+  sizeOf    _ = sizeOf    (undefined :: Ptr ())
+  alignment _ = alignment (undefined :: Ptr ())
+
+  peek p = do
+	     ptr <- peek (castPtr p)
+	     if ptr == nullPtr
+	       then return Nothing
+	       else liftM Just $ peek ptr
+
+  poke p v = do
+	       ptr <- case v of
+		        Nothing -> return nullPtr
+			Just v' -> new v'
+               poke (castPtr p) ptr
+
+
+-- Conditional results using 'Maybe'
+-- ---------------------------------
+
+-- Wrap the result into a 'Maybe' type.
+--
+-- * the predicate determines when the result is considered to be non-existing,
+--   ie, it is represented by `Nothing'
+--
+-- * the second argument allows to map a result wrapped into `Just' to some
+--   other domain
+--
+nothingIf       :: (a -> Bool) -> (a -> b) -> a -> Maybe b
+nothingIf p f x  = if p x then Nothing else Just $ f x
+
+-- |Instance for special casing null pointers.
+--
+nothingIfNull :: (Ptr a -> b) -> Ptr a -> Maybe b
+nothingIfNull  = nothingIf (== nullPtr)
+
+
+-- Support for bit masks
+-- ---------------------
+
+-- Given a list of enumeration values that represent bit masks, combine these
+-- masks using bitwise disjunction.
+--
+combineBitMasks :: (Enum a, Bits b) => [a] -> b
+combineBitMasks = foldl (.|.) 0 . map (fromIntegral . fromEnum)
+
+-- Tests whether the given bit mask is contained in the given bit pattern
+-- (i.e., all bits set in the mask are also set in the pattern).
+--
+containsBitMask :: (Bits a, Enum b) => a -> b -> Bool
+bits `containsBitMask` bm = let bm' = fromIntegral . fromEnum $ bm
+			    in
+			    bm' .&. bits == bm'
+
+-- |Given a bit pattern, yield all bit masks that it contains.
+--
+-- * This does *not* attempt to compute a minimal set of bit masks that when
+--   combined yield the bit pattern, instead all contained bit masks are
+--   produced.
+--
+extractBitMasks :: (Bits a, Enum b, Bounded b) => a -> [b]
+extractBitMasks bits = 
+  [bm | bm <- [minBound..maxBound], bits `containsBitMask` bm]
+
+
+-- Conversion routines
+-- -------------------
+
+-- |Integral conversion
+--
+cIntConv :: (Integral a, Integral b) => a -> b
+cIntConv  = fromIntegral
+
+-- |Floating conversion
+--
+cFloatConv :: (RealFloat a, RealFloat b) => a -> b
+cFloatConv  = realToFrac
+-- As this conversion by default goes via `Rational', it can be very slow...
+{-# RULES 
+  "cFloatConv/Float->Float"   forall (x::Float).  cFloatConv x = x;
+  "cFloatConv/Double->Double" forall (x::Double). cFloatConv x = x
+ #-}
+
+-- |Obtain C value from Haskell 'Bool'.
+--
+cFromBool :: Num a => Bool -> a
+cFromBool  = fromBool
+
+-- |Obtain Haskell 'Bool' from C value.
+--
+cToBool :: Num a => a -> Bool
+cToBool  = toBool
+
+-- |Convert a C enumeration to Haskell.
+--
+cToEnum :: (Integral i, Enum e) => i -> e
+cToEnum  = toEnum . cIntConv
+
+-- |Convert a Haskell enumeration to C.
+--
+cFromEnum :: (Enum e, Integral i) => e -> i
+cFromEnum  = cIntConv . fromEnum