accelerate-io-0.15.0.0: Read and write Accelerate arrays in various formats

Copyright[2010..2012] Sean Seefried [2010..2014] Trevor L. McDonell
LicenseBSD3
MaintainerManuel M T Chakravarty <chak@cse.unsw.edu.au>
Stabilityexperimental
Portabilitynon-portable (GHC extensions)
Safe HaskellNone
LanguageHaskell98

Data.Array.Accelerate.IO

Contents

Description

This module provides efficient conversion routines between different array types and Accelerate arrays.

Synopsis

Array libraries

Data.Array.Repa

This provides an efficient non-copying Repa manifest array representation that can be passed directly to Accelerate.

The standard rules for dealing with manifest Repa arrays apply:

  • If you want to have Repa computeP directly into an Accelerate array, the source array must have a delayed representation.
  • If you want to copy between manifest arrays, use copyP instead.

data A

The representation tag for manifest arrays based on Data.Array.Accelerate.

The Accelerate array implementation is based on type families and picks an efficient, unboxed representation for every element type. Moreover, these arrays can be handed efficiently (without copying) to Accelerate programs for further computation.

Instances

Elt e => Target A e

Filling Accelerate arrays

Elt e => Source A e

Reading elements of the Accelerate array

data MVec A = MAVec (MutableArrayData (EltRepr e)) 
data Array A sh e = AAccelerate !sh !(ArrayData (EltRepr e)) 

class (Shape r, Shape a) => Shapes r a | a -> r, r -> a

Index conversion and equivalence statement between Repa and Accelerate array shapes. That is, a n-dimensional Repa array will produce an n-dimensional Accelerate array of the same extent, and vice-versa.

Minimal complete definition

toR, toA

Instances

Shapes Z Z 
Shapes sr sa => Shapes ((:.) sr Int) ((:.) sa Int) 

fromRepa :: (Shapes sh sh', Elt e) => Array A sh e -> Array sh' e

O(1). Unpack to an Accelerate array.

toRepa :: Shapes sh sh' => Array sh' e -> Array A sh e

O(1). Wrap an Accelerate array.

computeAccS :: (Load r sh e, Elt e) => Array r sh e -> Array A sh e

Sequential computation of array elements

computeAccP :: (Load r sh e, Elt e, Monad m) => Array r sh e -> m (Array A sh e)

Parallel computation of array elements

Data.Vector.Storable

This provides an efficient non-copying conversion between storable vectors and Accelerate arrays.

type family Vectors e

A family of types that represents a collection of storable Vectors. The structure of the collection depends on the element type e.

For example:

  • if e :: Int, then Vectors (EltRepr e) :: ((), Vector Int)
  • if e :: (Double, Float), then Vectors (EltRepr e) :: (((), Vector Double), Vector Float)

toVectors :: (Shape sh, Elt e) => Array sh e -> Vectors (EltRepr e)

O(1). Turn the Accelerate array into a collection of storable Vectors. The element type of the array e will determine the structure of the output collection. See Vectors.

Data will be output in row-major order.

fromVectors :: (Shape sh, Elt e) => sh -> Vectors (EltRepr e) -> Array sh e

O(1). Treat a set of storable vectors as Accelerate arrays. The type of elements e in the output Accelerate array determines the structure of the collection that will be required as the second argument. See Vectors.

Data will be consumed from the vector in row-major order. You must make sure that each of the input vectors contains the right number of elements

Specialised file IO

Bitmap images

Reading and writing arrays as uncompressed 24 or 32-bit Windows BMP files.

type RGBA32 = Word32

Packed RGBA pixel data

readImageFromBMP :: FilePath -> IO (Either Error (Array DIM2 RGBA32))

Read RGBA components from a BMP file.

writeImageToBMP :: FilePath -> Array DIM2 RGBA32 -> IO ()

Write the image data to a file.

Manipulating pixels

unpackRGBA32 :: Exp RGBA32 -> Exp (Word8, Word8, Word8, Word8)

Unpack a RGBA32 value into a tuple of (Red, Green, Blue, Alpha) values.

packRGBA32 :: Exp (Word8, Word8, Word8, Word8) -> Exp RGBA32

Promote a tuple of (Red, Green, Blue, Alpha) values into a packed RGBA32 value.

luminanceOfRGBA32 :: (Elt a, IsFloating a) => Exp RGBA32 -> Exp a

Convert an RGBA colour to its luminance value in the range [0..1].

rgba32OfLuminance :: (Elt a, IsFloating a) => Exp a -> Exp RGBA32

Convert a value in the range [0..1] to a grey RGB colour.

rgba32OfFloat :: (Elt a, IsFloating a) => Exp (a, a, a, a) -> Exp RGBA32

Promote a tuple of (Red, Green, Blue, Alpha) values in the range [0..1] into a packed RGBA32.

Low-level conversions

Copying conversions of low-level primitive data, stored in one-dimensional row-major blocks of contiguous memory. To use these, you should really know what you are doing. Potential pitfalls include:

  • copying from memory your program doesn't have access to (e.g. it may be unallocated, or not enough memory is allocated)
  • memory alignment errors

Data.ByteString

fromByteString :: (Shape sh, Elt e) => sh -> ByteStrings (EltRepr e) -> IO (Array sh e)

Block copies bytes from a collection of ByteStrings to freshly allocated Accelerate array.

The type of elements (e) in the output Accelerate array determines the structure of the collection of ByteStrings that will be required as the second argument to this function. See ByteStrings

toByteString :: (Shape sh, Elt e) => Array sh e -> IO (ByteStrings (EltRepr e))

Block copy from an Accelerate array to a collection of freshly allocated ByteStrings.

The type of elements (e) in the input Accelerate array determines the structure of the collection of ByteStrings that will be output. See ByteStrings

Raw pointers

type family BlockPtrs e

A family of types that represents a collection of pointers that are the source/destination addresses for a block copy. The structure of the collection of pointers depends on the element type e.

e.g.

If e :: Int, then BlockPtrs (EltRepr e) :: ((), Ptr Int)

If e :: (Double, Float) then BlockPtrs (EltRepr e) :: (((), Ptr Double), Ptr Float)

fromPtr :: (Shape sh, Elt e) => sh -> BlockPtrs (EltRepr e) -> IO (Array sh e)

Block copy regions of memory into a freshly allocated Accelerate array. The type of elements (e) in the output Accelerate array determines the structure of the collection of pointers that will be required as the second argument to this function. See BlockPtrs

Each one of these pointers points to a block of memory that is the source of data for the Accelerate array (unlike function toArray where one passes in function which copies data to a destination address.).

toPtr :: (Shape sh, Elt e) => Array sh e -> BlockPtrs (EltRepr e) -> IO ()

Block copy from Accelerate array to pre-allocated regions of memory. The type of element of the input Accelerate array (e) determines the structure of the collection of pointers that will be required as the second argument to this function. See BlockPtrs

The memory associated with the pointers must have already been allocated.

Direct copying functions

type BlockCopyFun e = Ptr e -> Int -> IO ()

Functions of this type are passed as arguments to toArray. A function of this type should copy a number of bytes (equal to the value of the parameter of type Int) to the destination memory pointed to by Ptr e.

type family BlockCopyFuns e

Represents a collection of "block copy functions" (see BlockCopyFun). The structure of the collection of BlockCopyFuns depends on the element type e.

e.g.

If e :: Float then BlockCopyFuns (EltRepr e) :: ((), Ptr Float -> Int -> IO ())

If e :: (Double, Float) then BlockCopyFuns (EltRepr e) :: (((), Ptr Double -> Int -> IO ()), Ptr Float -> Int -> IO ())

fromArray :: (Shape sh, Elt e) => Array sh e -> BlockCopyFuns (EltRepr e) -> IO ()

Copy values from an Accelerate array using a collection of functions that have type BlockCopyFun. The argument of type Ptr e in each of these functions refers to the address of the source block of memory in the Accelerate Array. The destination address is implicit. e.g. the BlockCopyFun could be the result of partially application to a Ptr e pointing to the destination block.

The structure of this collection of functions depends on the elemente type e. Each function (of type BlockCopyFun) copies data to a destination address (pointed to by the argument of type Ptr ()).

Unless there is a particularly pressing reason to use this function, the fromPtr function is sufficient as it uses an efficient low-level call to libc's memcpy to perform the copy.

toArray :: (Shape sh, Elt e) => sh -> BlockCopyFuns (EltRepr e) -> IO (Array sh e)

Copy values to a freshly allocated Accelerate array using a collection of functions that have type BlockCopyFun. The argument of type Ptr e in each of these functions refers to the address of the destination block of memory in the Accelerate Array. The source address is implicit. e.g. the BlockCopyFun could be the result of a partial application to a Ptr e pointing to the source block.

The structure of this collection of functions depends on the elemente type e. Each function (of type BlockCopyFun) copies data to a destination address (pointed to by the argument of type Ptr ()).

Unless there is a particularly pressing reason to use this function, the fromPtr function is sufficient as it uses an efficient low-level call to libc's memcpy to perform the copy.