NAME

Dyn - dyncall Backed FFI

SYNOPSIS

use Dyn qw[:dl];                                       # Exports nothing by default
my $lib = dlLoadLibrary('/usr/lib/libm-2.33.so');      # or a .dll on Windows or .dylib on macOS
my $exp = Dyn::call( $lib, 'pow', 'dd)d', 2.0, 10.0 ); # 1024

DESCRIPTION

Dyn is a wrapper around dyncall.

Dyn includes...

• Dyn::Call

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

  Functions can be imported with the :dc tag.

• Dyn::Callback

  Callback interface of dyncall located in dyncallback.

  Functions can be imported with the :dcb tag.

• Dyn::Load

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

  Functions can be imported with the :dl tag.

Functions

While most of the upstream API is covered in the Dyn::Call, Dyn::Callback, and Dyn::Load packages, all the sugar is right here in Dyn. All of these methods may be imported by name or with the :sugar tag.

Note that everything here is subject to change before v1.0.

call( ... )

Invokes the function according to the provided signature.

    my $value = call( dlLoadLibrary($path), 'pow', 'dd)d', 2.0, 10.0 );

Expected parameters include:

• libhandle - pointer returned by dlLoadLibrary( ... )
• name - the name of the symbol to call
• signature - signature defining argument types, return type, and optionally the calling convention used
• ... - any arguments to bind to the call

Signatures

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)

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
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

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

Check out FFI::Platypus for a more robust and mature FFI.

LICENSE

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.

AUTHOR

Sanko Robinson sanko@cpan.org