base-4.10.1.0: Basic libraries

Copyright(c) The FFI task force 2001
Licensesee libraries/base/LICENSE
Maintainerffi@haskell.org
Stabilityprovisional
Portabilityportable
Safe HaskellTrustworthy
LanguageHaskell2010

Foreign.Storable

Description

The module Foreign.Storable provides most elementary support for marshalling and is part of the language-independent portion of the Foreign Function Interface (FFI), and will normally be imported via the Foreign module.

Synopsis

Documentation

class Storable a where Source #

The member functions of this class facilitate writing values of primitive types to raw memory (which may have been allocated with the above mentioned routines) and reading values from blocks of raw memory. The class, furthermore, includes support for computing the storage requirements and alignment restrictions of storable types.

Memory addresses are represented as values of type Ptr a, for some a which is an instance of class Storable. The type argument to Ptr helps provide some valuable type safety in FFI code (you can't mix pointers of different types without an explicit cast), while helping the Haskell type system figure out which marshalling method is needed for a given pointer.

All marshalling between Haskell and a foreign language ultimately boils down to translating Haskell data structures into the binary representation of a corresponding data structure of the foreign language and vice versa. To code this marshalling in Haskell, it is necessary to manipulate primitive data types stored in unstructured memory blocks. The class Storable facilitates this manipulation on all types for which it is instantiated, which are the standard basic types of Haskell, the fixed size Int types (Int8, Int16, Int32, Int64), the fixed size Word types (Word8, Word16, Word32, Word64), StablePtr, all types from Foreign.C.Types, as well as Ptr.

Minimal complete definition

sizeOf, alignment, (peek | peekElemOff | peekByteOff), (poke | pokeElemOff | pokeByteOff)

Methods

sizeOf :: a -> Int Source #

Computes the storage requirements (in bytes) of the argument. The value of the argument is not used.

alignment :: a -> Int Source #

Computes the alignment constraint of the argument. An alignment constraint x is fulfilled by any address divisible by x. The value of the argument is not used.

peekElemOff :: Ptr a -> Int -> IO a Source #

Read a value from a memory area regarded as an array of values of the same kind. The first argument specifies the start address of the array and the second the index into the array (the first element of the array has index 0). The following equality holds,

peekElemOff addr idx = IOExts.fixIO $ \result ->
  peek (addr `plusPtr` (idx * sizeOf result))

Note that this is only a specification, not necessarily the concrete implementation of the function.

pokeElemOff :: Ptr a -> Int -> a -> IO () Source #

Write a value to a memory area regarded as an array of values of the same kind. The following equality holds:

pokeElemOff addr idx x = 
  poke (addr `plusPtr` (idx * sizeOf x)) x

peekByteOff :: Ptr b -> Int -> IO a Source #

Read a value from a memory location given by a base address and offset. The following equality holds:

peekByteOff addr off = peek (addr `plusPtr` off)

pokeByteOff :: Ptr b -> Int -> a -> IO () Source #

Write a value to a memory location given by a base address and offset. The following equality holds:

pokeByteOff addr off x = poke (addr `plusPtr` off) x

peek :: Ptr a -> IO a Source #

Read a value from the given memory location.

Note that the peek and poke functions might require properly aligned addresses to function correctly. This is architecture dependent; thus, portable code should ensure that when peeking or poking values of some type a, the alignment constraint for a, as given by the function alignment is fulfilled.

poke :: Ptr a -> a -> IO () Source #

Write the given value to the given memory location. Alignment restrictions might apply; see peek.

Instances

Storable Bool Source #

Since: 2.1

Storable Char Source #

Since: 2.1

Storable Double Source #

Since: 2.1

Storable Float Source #

Since: 2.1

Storable Int Source #

Since: 2.1

Storable Int8 Source #

Since: 2.1

Storable Int16 Source #

Since: 2.1

Storable Int32 Source #

Since: 2.1

Storable Int64 Source #

Since: 2.1

Storable Word Source #

Since: 2.1

Storable Word8 Source #

Since: 2.1

Storable Word16 Source #

Since: 2.1

Storable Word32 Source #

Since: 2.1

Storable Word64 Source #

Since: 2.1

Storable () Source #

Since: 4.9.0.0

Methods

sizeOf :: () -> Int Source #

alignment :: () -> Int Source #

peekElemOff :: Ptr () -> Int -> IO () Source #

pokeElemOff :: Ptr () -> Int -> () -> IO () Source #

peekByteOff :: Ptr b -> Int -> IO () Source #

pokeByteOff :: Ptr b -> Int -> () -> IO () Source #

peek :: Ptr () -> IO () Source #

poke :: Ptr () -> () -> IO () Source #

Storable Fingerprint Source #

Since: 4.4.0.0

Storable IntPtr Source # 
Storable WordPtr Source # 
Storable CUIntMax Source # 
Storable CIntMax Source # 
Storable CUIntPtr Source # 
Storable CIntPtr Source # 
Storable CSUSeconds Source # 
Storable CUSeconds Source # 
Storable CTime Source # 
Storable CClock Source # 
Storable CSigAtomic Source # 
Storable CWchar Source # 
Storable CSize Source # 
Storable CPtrdiff Source # 
Storable CDouble Source # 
Storable CFloat Source # 
Storable CBool Source # 
Storable CULLong Source # 
Storable CLLong Source # 
Storable CULong Source # 
Storable CLong Source # 
Storable CUInt Source # 
Storable CInt Source # 
Storable CUShort Source # 
Storable CShort Source # 
Storable CUChar Source # 
Storable CSChar Source # 
Storable CChar Source # 
Storable Fd Source # 

Methods

sizeOf :: Fd -> Int Source #

alignment :: Fd -> Int Source #

peekElemOff :: Ptr Fd -> Int -> IO Fd Source #

pokeElemOff :: Ptr Fd -> Int -> Fd -> IO () Source #

peekByteOff :: Ptr b -> Int -> IO Fd Source #

pokeByteOff :: Ptr b -> Int -> Fd -> IO () Source #

peek :: Ptr Fd -> IO Fd Source #

poke :: Ptr Fd -> Fd -> IO () Source #

Storable CTimer Source # 
Storable CKey Source # 
Storable CId Source # 
Storable CFsFilCnt Source # 
Storable CFsBlkCnt Source # 
Storable CClockId Source # 
Storable CBlkCnt Source # 
Storable CBlkSize Source # 
Storable CRLim Source # 
Storable CTcflag Source # 
Storable CSpeed Source # 
Storable CCc Source # 
Storable CUid Source # 
Storable CNlink Source # 
Storable CGid Source # 
Storable CSsize Source # 
Storable CPid Source # 
Storable COff Source # 
Storable CMode Source # 
Storable CIno Source # 
Storable CDev Source # 
(Storable a, Integral a) => Storable (Ratio a) Source #

Since: 4.8.0.0

Methods

sizeOf :: Ratio a -> Int Source #

alignment :: Ratio a -> Int Source #

peekElemOff :: Ptr (Ratio a) -> Int -> IO (Ratio a) Source #

pokeElemOff :: Ptr (Ratio a) -> Int -> Ratio a -> IO () Source #

peekByteOff :: Ptr b -> Int -> IO (Ratio a) Source #

pokeByteOff :: Ptr b -> Int -> Ratio a -> IO () Source #

peek :: Ptr (Ratio a) -> IO (Ratio a) Source #

poke :: Ptr (Ratio a) -> Ratio a -> IO () Source #

Storable (StablePtr a) Source #

Since: 2.1

Storable (Ptr a) Source #

Since: 2.1

Methods

sizeOf :: Ptr a -> Int Source #

alignment :: Ptr a -> Int Source #

peekElemOff :: Ptr (Ptr a) -> Int -> IO (Ptr a) Source #

pokeElemOff :: Ptr (Ptr a) -> Int -> Ptr a -> IO () Source #

peekByteOff :: Ptr b -> Int -> IO (Ptr a) Source #

pokeByteOff :: Ptr b -> Int -> Ptr a -> IO () Source #

peek :: Ptr (Ptr a) -> IO (Ptr a) Source #

poke :: Ptr (Ptr a) -> Ptr a -> IO () Source #

Storable (FunPtr a) Source #

Since: 2.1

Methods

sizeOf :: FunPtr a -> Int Source #

alignment :: FunPtr a -> Int Source #

peekElemOff :: Ptr (FunPtr a) -> Int -> IO (FunPtr a) Source #

pokeElemOff :: Ptr (FunPtr a) -> Int -> FunPtr a -> IO () Source #

peekByteOff :: Ptr b -> Int -> IO (FunPtr a) Source #

pokeByteOff :: Ptr b -> Int -> FunPtr a -> IO () Source #

peek :: Ptr (FunPtr a) -> IO (FunPtr a) Source #

poke :: Ptr (FunPtr a) -> FunPtr a -> IO () Source #

Storable a => Storable (Identity a) Source # 
Storable a => Storable (Complex a) Source #

Since: 4.8.0.0

Methods

sizeOf :: Complex a -> Int Source #

alignment :: Complex a -> Int Source #

peekElemOff :: Ptr (Complex a) -> Int -> IO (Complex a) Source #

pokeElemOff :: Ptr (Complex a) -> Int -> Complex a -> IO () Source #

peekByteOff :: Ptr b -> Int -> IO (Complex a) Source #

pokeByteOff :: Ptr b -> Int -> Complex a -> IO () Source #

peek :: Ptr (Complex a) -> IO (Complex a) Source #

poke :: Ptr (Complex a) -> Complex a -> IO () Source #

Storable a => Storable (Const k a b) Source # 

Methods

sizeOf :: Const k a b -> Int Source #

alignment :: Const k a b -> Int Source #

peekElemOff :: Ptr (Const k a b) -> Int -> IO (Const k a b) Source #

pokeElemOff :: Ptr (Const k a b) -> Int -> Const k a b -> IO () Source #

peekByteOff :: Ptr b -> Int -> IO (Const k a b) Source #

pokeByteOff :: Ptr b -> Int -> Const k a b -> IO () Source #

peek :: Ptr (Const k a b) -> IO (Const k a b) Source #

poke :: Ptr (Const k a b) -> Const k a b -> IO () Source #