Data pointers |
| data Ptr |
A value of type Ptr a represents a pointer to an object, or an
array of objects, which may be marshalled to or from Haskell values
of type a. The type a will normally be an instance of class Storable which provides the marshalling operations. |
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| nullPtr :: Ptr a |
The constant nullPtr contains a distinguished value of Ptr that is not associated with a valid memory location. |
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| castPtr :: Ptr a -> Ptr b | The castPtr function casts a pointer from one type to another. |
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| plusPtr :: Ptr a -> Int -> Ptr b | Advances the given address by the given offset in bytes. |
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| alignPtr :: Ptr a -> Int -> Ptr a |
Given an arbitrary address and an alignment constraint,
alignPtr yields the next higher address that fulfills the
alignment constraint. An alignment constraint x is fulfilled by any address divisible by x. This operation is idempotent. |
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| minusPtr :: Ptr a -> Ptr b -> Int |
Computes the offset required to get from the first to the second argument. We have p2 == p1 `plusPtr` (p2 `minusPtr` p1) |
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Function pointers |
| data FunPtr |
A value of type FunPtr a is a pointer to a piece of code. It
may be the pointer to a C function or to a Haskell function created
using foreign export dynamic. A foreign export
dynamic should normally be declared to produce a
FunPtr of the correct type. For example:
type Compare = Int -> Int -> Bool
foreign export dynamic mkCompare :: Compare -> IO (FunPtr Compare) |
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| nullFunPtr :: FunPtr a |
The constant nullFunPtr contains a
distinguished value of Ptr that is not associated with a valid memory location |
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