base-4.12.0.0: 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

Instance details

Defined in Foreign.Storable

Storable Char Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Double Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Float Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Int Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Int8 Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Int16 Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Int32 Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Int64 Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Word Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Word8 Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Word16 Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Word32 Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable Word64 Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

Storable () Source #

Since: 4.9.0.0

Instance details

Defined in Foreign.Storable

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

Instance details

Defined in Foreign.Storable

Storable IntPtr Source # 
Instance details

Defined in Foreign.Ptr

Storable WordPtr Source # 
Instance details

Defined in Foreign.Ptr

Storable CUIntMax Source # 
Instance details

Defined in Foreign.C.Types

Storable CIntMax Source # 
Instance details

Defined in Foreign.C.Types

Storable CUIntPtr Source # 
Instance details

Defined in Foreign.C.Types

Storable CIntPtr Source # 
Instance details

Defined in Foreign.C.Types

Storable CSUSeconds Source # 
Instance details

Defined in Foreign.C.Types

Storable CUSeconds Source # 
Instance details

Defined in Foreign.C.Types

Storable CTime Source # 
Instance details

Defined in Foreign.C.Types

Storable CClock Source # 
Instance details

Defined in Foreign.C.Types

Storable CSigAtomic Source # 
Instance details

Defined in Foreign.C.Types

Storable CWchar Source # 
Instance details

Defined in Foreign.C.Types

Storable CSize Source # 
Instance details

Defined in Foreign.C.Types

Storable CPtrdiff Source # 
Instance details

Defined in Foreign.C.Types

Storable CDouble Source # 
Instance details

Defined in Foreign.C.Types

Storable CFloat Source # 
Instance details

Defined in Foreign.C.Types

Storable CBool Source # 
Instance details

Defined in Foreign.C.Types

Storable CULLong Source # 
Instance details

Defined in Foreign.C.Types

Storable CLLong Source # 
Instance details

Defined in Foreign.C.Types

Storable CULong Source # 
Instance details

Defined in Foreign.C.Types

Storable CLong Source # 
Instance details

Defined in Foreign.C.Types

Storable CUInt Source # 
Instance details

Defined in Foreign.C.Types

Storable CInt Source # 
Instance details

Defined in Foreign.C.Types

Storable CUShort Source # 
Instance details

Defined in Foreign.C.Types

Storable CShort Source # 
Instance details

Defined in Foreign.C.Types

Storable CUChar Source # 
Instance details

Defined in Foreign.C.Types

Storable CSChar Source # 
Instance details

Defined in Foreign.C.Types

Storable CChar Source # 
Instance details

Defined in Foreign.C.Types

Storable Fd Source # 
Instance details

Defined in System.Posix.Types

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 # 
Instance details

Defined in System.Posix.Types

Storable CId Source # 
Instance details

Defined in System.Posix.Types

Storable CFsFilCnt Source # 
Instance details

Defined in System.Posix.Types

Storable CFsBlkCnt Source # 
Instance details

Defined in System.Posix.Types

Storable CBlkCnt Source # 
Instance details

Defined in System.Posix.Types

Storable CBlkSize Source # 
Instance details

Defined in System.Posix.Types

Storable CRLim Source # 
Instance details

Defined in System.Posix.Types

Storable CTcflag Source # 
Instance details

Defined in System.Posix.Types

Storable CSpeed Source # 
Instance details

Defined in System.Posix.Types

Storable CCc Source # 
Instance details

Defined in System.Posix.Types

Storable CUid Source # 
Instance details

Defined in System.Posix.Types

Storable CNlink Source # 
Instance details

Defined in System.Posix.Types

Storable CGid Source # 
Instance details

Defined in System.Posix.Types

Storable CSsize Source # 
Instance details

Defined in System.Posix.Types

Storable CPid Source # 
Instance details

Defined in System.Posix.Types

Storable COff Source # 
Instance details

Defined in System.Posix.Types

Storable CMode Source # 
Instance details

Defined in System.Posix.Types

Storable CIno Source # 
Instance details

Defined in System.Posix.Types

Storable CDev Source # 
Instance details

Defined in System.Posix.Types

(Storable a, Integral a) => Storable (Ratio a) Source #

Since: 4.8.0.0

Instance details

Defined in Foreign.Storable

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

Instance details

Defined in Foreign.Storable

Storable (Ptr a) Source #

Since: 2.1

Instance details

Defined in Foreign.Storable

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

Instance details

Defined in Foreign.Storable

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 #

Since: 4.9.0.0

Instance details

Defined in Data.Functor.Identity

Storable a => Storable (Complex a) Source #

Since: 4.8.0.0

Instance details

Defined in Data.Complex

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 a b) Source #

Since: 4.9.0.0

Instance details

Defined in Data.Functor.Const

Methods

sizeOf :: Const a b -> Int Source #

alignment :: Const a b -> Int Source #

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

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

peekByteOff :: Ptr b0 -> Int -> IO (Const a b) Source #

pokeByteOff :: Ptr b0 -> Int -> Const a b -> IO () Source #

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

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