Details

• ForeignFunctionLoad returns the ForeignFunction object.
• lib is resolved with FindLibrary.
• lib must be a C-compatible dynamic library.
• Supported types generally align with those supported by the Wolfram Compiler.
• Possible argument and return types and their corresponding C types include:
• "UnsignedInteger8"uint8_tunsigned 8-bit integer "Integer8"int8_tsigned 8-bit integer "UnsignedInteger16"uint16_tunsigned 16-bit integer "Integer16"int16_tsigned 16-bit integer "UnsignedInteger32"uint32_tunsigned 32-bit integer "Integer32"int32_tsigned 32-bit integer "UnsignedInteger64"uint64_tunsigned 64-bit integer "Integer64"int64_tsigned 64-bit integer "CUnsignedChar"unsigned charC-compatible unsigned char "CSignedChar"signed charC-compatible signed char "CUnsignedShort"unsigned shortC-compatible unsigned short "CShort"shortC-compatible short "CUnsignedInt"unsigned intC-compatible unsigned int "CInt"intC-compatible int "CUnsignedLong"unsigned longC-compatible unsigned long "CLong"longC-compatible long "CSizeT"size_tC-compatible size_t "CFloat"floatC-compatible float "CDouble"doubleC-compatible double "OpaqueRawPointer"void*opaque pointer "RawPointer"::[t]t*typed pointer {ty₁,ty₂,…}struct {ty₁ f₁; ty₂ f₂; …}struct or product type "Void"voidno output (only in output types)
• Struct or product types can also be written as "ListTuple"::[ty₁,ty₂, …].
• In ForeignFunctionLoad[ptr,…], ptr must be an OpaqueRawPointer pointing to a valid function in a library.

Examples

Basic Examples  (1)

Load a function from a library:

Call the function:

Scope  (2)

ForeignFunctionLoad uses FindLibrary to locate libraries:

Alternatively, find the library once with FindLibrary and pass it to ForeignFunctionLoad:

Get the pointer to a function in a library:

Load the foreign function by using the function pointer and specifying its type:

Applications  (2)

Create a foreign function for the RAND_bytes function from OpenSSL:

Create a buffer into which the random bytes can be written:

Generate the random bytes by calling RAND_bytes:

Read the output:

Package into a function:

The foreign function is very efficient:

Implement SHA256 using OpenSSL:

Create a buffer containing the plaintext to hash:

Create a buffer into which to write the hash:

Execute the hash:

Read the results from the ciphertext buffer:

Compare with the built-in function Hash:

Package into a function:

The packaged function is very efficient:

Properties & Relations  (1)

ForeignFunctionLoad can generally create callable links to libraries faster than custom links can be compiled:

However, the custom compiled versions can have less overhead:

Possible Issues  (3)

If the library does not exist, a Failure is returned:

If the function does not exist, a Failure is returned:

ForeignFunctionLoad will return $Failed if a type is not supported: