base-4.16.0.0: 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

Instances details
Storable Bool #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Char #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Double #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Float #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Int #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Int8 #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Int16 #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Int32 #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Int64 #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Word #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Word8 #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Word16 #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Word32 #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable Word64 #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable () #

Since: base-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 #

Since: base-4.4.0.0

Instance details

Defined in Foreign.Storable

Storable IntPtr # 
Instance details

Defined in Foreign.Ptr

Storable WordPtr # 
Instance details

Defined in Foreign.Ptr

Storable CBool # 
Instance details

Defined in Foreign.C.Types

Storable CChar # 
Instance details

Defined in Foreign.C.Types

Storable CClock # 
Instance details

Defined in Foreign.C.Types

Storable CDouble # 
Instance details

Defined in Foreign.C.Types

Storable CFloat # 
Instance details

Defined in Foreign.C.Types

Storable CInt # 
Instance details

Defined in Foreign.C.Types

Storable CIntMax # 
Instance details

Defined in Foreign.C.Types

Storable CIntPtr # 
Instance details

Defined in Foreign.C.Types

Storable CLLong # 
Instance details

Defined in Foreign.C.Types

Storable CLong # 
Instance details

Defined in Foreign.C.Types

Storable CPtrdiff # 
Instance details

Defined in Foreign.C.Types

Storable CSChar # 
Instance details

Defined in Foreign.C.Types

Storable CSUSeconds # 
Instance details

Defined in Foreign.C.Types

Storable CShort # 
Instance details

Defined in Foreign.C.Types

Storable CSigAtomic # 
Instance details

Defined in Foreign.C.Types

Storable CSize # 
Instance details

Defined in Foreign.C.Types

Storable CTime # 
Instance details

Defined in Foreign.C.Types

Storable CUChar # 
Instance details

Defined in Foreign.C.Types

Storable CUInt # 
Instance details

Defined in Foreign.C.Types

Storable CUIntMax # 
Instance details

Defined in Foreign.C.Types

Storable CUIntPtr # 
Instance details

Defined in Foreign.C.Types

Storable CULLong # 
Instance details

Defined in Foreign.C.Types

Storable CULong # 
Instance details

Defined in Foreign.C.Types

Storable CUSeconds # 
Instance details

Defined in Foreign.C.Types

Storable CUShort # 
Instance details

Defined in Foreign.C.Types

Storable CWchar # 
Instance details

Defined in Foreign.C.Types

Storable CBlkCnt # 
Instance details

Defined in System.Posix.Types

Storable CBlkSize # 
Instance details

Defined in System.Posix.Types

Storable CCc # 
Instance details

Defined in System.Posix.Types

Storable CClockId # 
Instance details

Defined in System.Posix.Types

Storable CDev # 
Instance details

Defined in System.Posix.Types

Storable CFsBlkCnt # 
Instance details

Defined in System.Posix.Types

Storable CFsFilCnt # 
Instance details

Defined in System.Posix.Types

Storable CGid # 
Instance details

Defined in System.Posix.Types

Storable CId # 
Instance details

Defined in System.Posix.Types

Storable CIno # 
Instance details

Defined in System.Posix.Types

Storable CKey # 
Instance details

Defined in System.Posix.Types

Storable CMode # 
Instance details

Defined in System.Posix.Types

Storable CNfds # 
Instance details

Defined in System.Posix.Types

Storable CNlink # 
Instance details

Defined in System.Posix.Types

Storable COff # 
Instance details

Defined in System.Posix.Types

Storable CPid # 
Instance details

Defined in System.Posix.Types

Storable CRLim # 
Instance details

Defined in System.Posix.Types

Storable CSocklen # 
Instance details

Defined in System.Posix.Types

Storable CSpeed # 
Instance details

Defined in System.Posix.Types

Storable CSsize # 
Instance details

Defined in System.Posix.Types

Storable CTcflag # 
Instance details

Defined in System.Posix.Types

Storable CTimer # 
Instance details

Defined in System.Posix.Types

Storable CUid # 
Instance details

Defined in System.Posix.Types

Storable Fd # 
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 IoSubSystem #

Since: base-4.9.0.0

Instance details

Defined in GHC.RTS.Flags

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

Since: base-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) #

Since: base-2.1

Instance details

Defined in Foreign.Storable

Storable (Ptr a) #

Since: base-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) #

Since: base-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 (Down a) #

Since: base-4.14.0.0

Instance details

Defined in Data.Ord

Methods

sizeOf :: Down a -> Int Source #

alignment :: Down a -> Int Source #

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

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

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

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

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

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

Storable a => Storable (Identity a) #

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Identity

Storable a => Storable (Complex a) #

Since: base-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) #

Since: base-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 #