► |  | FFI: Racket Foreign Interface

1 | Overview
2 | Loading Foreign Libraries
3 | C Types
4 | Pointer Functions
5 | Derived Utilities
6 | Miscellaneous Support
7 | Unexported Primitive Functions
| Index

▼ | 5 | Derived Utilities

5.1 | Safe Homogenous Vectors
5.2 | Safe C Vectors
5.3 | Tagged C Pointer Types
5.4 | Defining Bindings
5.5 | Allocation and Finalization
5.6 | Atomic Execution
5.7 | Speculatively Atomic Execution
5.8 | Objective-C FFI

On this page:

_ cvector
make-cvector
cvector
cvector?
cvector-length
cvector-type
cvector-ptr
cvector-ref
cvector-set!
cvector->list
list->cvector
make-cvector*

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#### 5.2`` Safe C Vectors

( require ffi/cvector )
( require ffi/unsafe/cvector )

The ffi/unsafe/cvector library exports the bindings of this section. The ffi/cvector library exports the same bindings, except for the unsafe make-cvector* operation.

The cvector form can be used as a type C vectors (i.e., a pointer to a memory block).

( _cvector mode type maybe-len)
_cvector

Like _bytes, _cvector can be used as a simple type that corresponds to a pointer that is managed as a safe C vector on the Racket side. The longer form behaves similarly to the _list and _vector custom types, except that _cvector is more efficient; no Racket list or vector is needed.

( make-cvector type length) → cvector?
type : ctype?
length : exact-nonnegative-integer?

Allocates a C vector using the given type and length. The resulting vector is not guaranteed to contain any particular values.

( cvector type val ...) → cvector?
type : ctype?
val : any/c

Creates a C vector of the given type, initialized to the given list of vals.

( cvector? v) → boolean?
v : any/c

Returns #t if v is a C vector, #f otherwise.

( cvector-length cvec) → exact-nonnegative-integer?
cvec : cvector?

Returns the length of a C vector.

( cvector-type cvec) → ctype?
cvec : cvector?

Returns the C type object of a C vector.

( cvector-ptr cvec) → cpointer?
cvec : cvector?

Returns the pointer that points at the beginning block of the given C vector.

( cvector-ref cvec k) → any
cvec : cvector?
k : exact-nonnegative-integer?

References the kth element of the cvec C vector. The result has the type that the C vector uses.

( cvector-set! cvec k val) → void?
cvec : cvector?
k : exact-nonnegative-integer?
val : any

Sets the kth element of the cvec C vector to val. The val argument should be a value that can be used with the type that the C vector uses.

( cvector->list cvec) → list?
cvec : cvector?

Converts the cvec C vector object to a list of values.

( list->cvector lst type) → cvector?
lst : list?
type : ctype?

Converts the list lst to a C vector of the given type.

( make-cvector* cptr type length) → cvector?
cptr : any/c
type : ctype?
length : exact-nonnegative-integer?

Constructs a C vector using an existing pointer object. This operation is not safe, so it is intended to be used in specific situations where the type and length are known.
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