From aea7e431c955bcde5527906872175c2051742a78 Mon Sep 17 00:00:00 2001
From: Mike Ledger <eleventynine@gmail.com>
Date: Mon, 24 Jun 2013 21:21:17 +1000
Subject: FFI helpers

---
 lib/Data/Packed/Foreign.hs | 85 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 lib/Data/Packed/Foreign.hs

(limited to 'lib')

diff --git a/lib/Data/Packed/Foreign.hs b/lib/Data/Packed/Foreign.hs
new file mode 100644
index 0000000..fe171b1
--- /dev/null
+++ b/lib/Data/Packed/Foreign.hs
@@ -0,0 +1,85 @@
+-- | FFI and hmatrix helpers.
+--
+-- Sample usage, to upload a perspective matrix to a shader.
+--
+-- @ glUniformMatrix4fv 0 1 (fromIntegral gl_TRUE) \`appMatrix\` perspective 0.01 100 (pi\/2) (4\/3) 
+-- @
+--
+module Data.Packed.Foreign where
+import Data.Packed.Internal
+import qualified Data.Vector.Storable as S
+import System.IO.Unsafe (unsafePerformIO)
+import Foreign (Ptr, ForeignPtr, Storable)
+import Foreign.C.Types (CInt)
+
+{-# INLINE app #-}
+-- | Only useful since it is left associated with a precedence of 1, unlike 'Prelude.$', which is right associative.
+-- e.g.
+--
+-- @
+-- someFunction
+--     \`appMatrixLen\` m
+--     \`appVectorLen\` v
+--     \`app\` other
+--     \`app\` arguments
+--     \`app\` go here
+-- @
+--
+-- One could also write:
+--
+-- @
+-- (someFunction 
+--     \`appMatrixLen\` m
+--     \`appVectorLen\` v) 
+--     other 
+--     arguments 
+--     (go here)
+-- @
+--
+app :: (a -> b) -> a -> b
+app f = f
+
+{-# INLINE appVector #-}
+appVector :: Storable a => (Ptr a -> b) -> Vector a -> b
+appVector f x = unsafePerformIO (S.unsafeWith x (return . f))
+
+{-# INLINE appVectorLen #-}
+appVectorLen :: Storable a => (CInt -> Ptr a -> b) -> Vector a -> b
+appVectorLen f x = unsafePerformIO (S.unsafeWith x (return . f (fromIntegral (S.length x))))
+
+{-# INLINE appMatrix #-}
+appMatrix :: Element a => (Ptr a -> b) -> Matrix a -> b
+appMatrix f x = unsafePerformIO (S.unsafeWith (flatten x) (return . f))
+
+{-# INLINE appMatrixLen #-}
+appMatrixLen :: Element a => (CInt -> CInt -> Ptr a -> b) -> Matrix a -> b
+appMatrixLen f x = unsafePerformIO (S.unsafeWith (flatten x) (return . f r c))
+  where
+    r = fromIntegral (rows x)
+    c = fromIntegral (cols x)
+
+{-# INLINE appMatrixRaw #-}
+appMatrixRaw :: Storable a => Matrix a -> (Ptr a -> b) -> b
+appMatrixRaw x f = unsafePerformIO (S.unsafeWith (xdat x) (return . f))
+
+{-# INLINE appMatrixRawLen #-}
+appMatrixRawLen :: Element a => (CInt -> CInt -> Ptr a -> b) -> Matrix a -> b
+appMatrixRawLen f x = unsafePerformIO (S.unsafeWith (xdat x) (return . f r c))
+  where
+    r = fromIntegral (rows x)
+    c = fromIntegral (cols x)
+
+infixl 1 `app`
+infixl 1 `appVector`
+infixl 1 `appMatrix`
+infixl 1 `appMatrixRaw`
+
+{-# INLINE unsafeMatrixToVector #-}
+-- | This will disregard the order of the matrix, and simply return it as-is.
+unsafeMatrixToVector :: Matrix a -> Vector a
+unsafeMatrixToVector = xdat
+
+{-# INLINE unsafeMatrixToForeignPtr #-}
+unsafeMatrixToForeignPtr :: Storable a => Matrix a -> (ForeignPtr a, Int)
+unsafeMatrixToForeignPtr m = S.unsafeToForeignPtr0 (xdat m)
+
-- 
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