▼The Racket Foreign Interface
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list->cblock
vector->cblock
vector->cpointer
flvector->cpointer
saved-errno
lookup-errno
cast
cblock->list
cblock->vector
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6 Miscellaneous Support

procedure

(list->cblock lst type) → any

  lst : list?
  type : ctype?
Allocates a memory block of an appropriate size, and initializes it using values from lst and the given type. The lst must hold values that can all be converted to C values according to the given type.

procedure

(vector->cblock vec type) → any

  vec : vector?
  type : type?
Like list->cblock, but for Racket vectors.

procedure

(vector->cpointer vec) → cpointer?

  vec : vector?
Returns a pointer to an array of _scheme values, which is the internal representation of vec.

procedure

(flvector->cpointer flvec) → cpointer?

  flvec : flvector?
Returns a pointer to an array of _double values, which is the internal representation of flvec.

procedure

(saved-errno) → exact-integer?

(saved-errno new-value) → void?
  new-value : exact-integer?
Returns or sets the error code saved for the current Racket thread. The saved error code is set after a foreign call with a non-#f #:save-errno option (see _fun and _cprocedure), but it can also be set explicitly (for example, to create mock foreign functions for testing).

Changed in version 6.4.0.9 of package base: Added the one-argument variant.

procedure

(lookup-errno sym) → exact-integer?

  sym : (or/c 'EINTR 'EEXIST 'EAGAIN)
Returns a platform-specific value corresponding to a Posix errno symbol. The set of supported symbols is likely to expand in the future.

procedure

(cast v from-type to-type) → any/c

  v : any/c
  from-type : ctype?
  to-type : ctype?
Converts v from a value matching from-type to a value matching to-type, where (ctype-sizeof from-type) matches (ctype-sizeof to-type).

The conversion is roughly equivalent to

(let ([p (malloc from-type)])
  (ptr-set! p from-type v)
  (ptr-ref p to-type))

If v is a cpointer, (cpointer-gcable? v) is true, and from-type and to-type are both based on _pointer or _gcpointer, then from-type is implicitly converted with _gcable to ensure that the result cpointer is treated as referring to memory that is managed by the garbage collector.

If v is a pointer with an offset component (e.g., from ptr-add), (cpointer-gcable? v) is true, and the result is a cpointer, then the result pointer has the same offset component as v. If (cpointer-gcable? v) is false, then any offset is folded into the pointer base for the result.

procedure

(cblock->list cblock type length) → list?

  cblock : any/c
  type : ctype?
  length : exact-nonnegative-integer?
Converts C cblock, which is a vector of types, to a Racket list. The arguments are the same as in the list->cblock. The length must be specified because there is no way to know where the block ends.

procedure

(cblock->vector cblock type length) → vector?

  cblock : any/c
  type : ctype?
  length : exact-nonnegative-integer?
Like cblock->vector, but for Racket vectors.

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