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Dyn - dyncall-Backed FFI Building Blocks


    use Dyn qw[:dc :dl]; # Imports all functions from Dyn::Call and Dyn::Load


Dyn is a wrapper around dyncall. It's here for the sake of convenience.

This distribution includes...


An encapsulation of architecture-, OS- and compiler-specific function call semantics.

Functions can be imported with the :dc tag.


Callback interface of dyncall located in dyncallback.

Functions can be imported with the :dcb tag.


Facilitates portable library symbol loading and access to functions in foreign dynamic libraries and code modules.

Functions can be imported with the :dl tag.


dyncall uses an almost pack-like syntax to define signatures. A signature is a character string that represents a function's arguments and return value types. This is an essential part of mapping the more flexible and often abstract data types provided in scripting languages to the strict machine-level data types used by C-libraries.

Here are some signature examples along with their equivalent C function prototypes:

    dyncall signature    C function prototype
    )v                   void      f1 ( )
    ii)i                 int       f2 ( int, int )
    p)L                  long long f3 ( void * )
    p)v                  void      f4 ( int ** )
    iBcdZ)d              double    f5 ( int, bool, char, double, const char * )
    _esl_.di)v           void      f6 ( short a, long long b, ... ) (for (promoted) varargs: double, int)
    (Zi)i                int       f7 ( const char *, int )
    (iiid)v              void      f8 ( int, int, int, double )

The following types are supported:

    Signature character     C/C++ data type
    v                       void
    B                       _Bool, bool
    c                       char
    C                       unsigned char
    s                       short
    S                       unsigned short
    i                       int
    I                       unsigned int
    j                       long
    J                       unsigned long
    l                       long long, int64_t
    L                       unsigned long long, uint64_t
    f                       float
    d                       double
    p                       void *
    Z                       const char * (pointer to a C string)
    A                       aggregate (struct/union described out-of-band via DCaggr)

See Dyn::Call for importable values.

Please note that using a ( at the beginning of a signature string is possible, although not required. The character doesn't have any meaning and will simply be ignored. However, using it prevents annoying syntax highlighting problems with some code editors.

Calling convention modes can be switched using the signature string, as well. An _ in the signature string is followed by a character specifying what calling convention to use, as this effects how arguments are passed. This makes only sense if there are multiple co-existing calling conventions on a single platform. Usually, this is done at the beginning of the string, except in special cases, like specifying where the varargs part of a variadic function begins. The following signature characters exist:

    Signature character   Calling Convention
    :                     platform's default calling convention
    *                     C++ this calls (platform native)
    e                     vararg function
    .                     vararg function's variadic/ellipsis part (...), to be specified before first vararg
    c                     only on x86: cdecl
    s                     only on x86: stdcall
    F                     only on x86: fastcall (MS)
    f                     only on x86: fastcall (GNU)
    +                     only on x86: thiscall (MS)
    #                     only on x86: thiscall (GNU)
    A                     only on ARM: ARM mode
    a                     only on ARM: THUMB mode
    $                     syscall

See Dyn::Call for importable values.

Platform Support

The dyncall library runs on many different platforms and operating systems (including Windows, Linux, OpenBSD, FreeBSD, macOS, DragonFlyBSD, NetBSD, Plan9, iOS, Haiku, Nintendo DS, Playstation Portable, Solaris, Minix, Raspberry Pi, ReactOS, etc.) and processors (x86, x64, arm (arm & thumb mode), arm64, mips, mips64, ppc32, ppc64, sparc, sparc64, etc.).

See Also

Affix for a dyncall wrapper with some of the rough edges sanded down.

FFI::Platypus for a mature, well-tested FFI.


Copyright (C) Sanko Robinson.

This library is free software; you can redistribute it and/or modify it under the terms found in the Artistic License 2. Other copyrights, terms, and conditions may apply to data transmitted through this module.


Sanko Robinson <>