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# 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](https://dyncall.org/).

Dyn includes...

- [Dyn::Call](https://metacpan.org/pod/Dyn%3A%3ACall)

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

    Functions can be imported with the `:dc` tag.

- [Dyn::Callback](https://metacpan.org/pod/Dyn%3A%3ACallback)

    Callback interface of `dyncall` located in `dyncallback`.

    Functions can be imported with the `:dcb` tag.

- [Dyn::Load](https://metacpan.org/pod/Dyn%3A%3ALoad)

    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](https://metacpan.org/pod/Dyn%3A%3ACall),
[Dyn::Callback](https://metacpan.org/pod/Dyn%3A%3ACallback), and [Dyn::Load](https://metacpan.org/pod/Dyn%3A%3ALoad) 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](#signatures).

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

Expected parameters include:

- `libhandle` - pointer returned by [`dlLoadLibrary( ... )`](https://metacpan.org/pod/Dyn%3A%3ALoad#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 speci�‘d before �〉st 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 &amp; thumb mode), arm64,
mips, mips64, ppc32, ppc64, sparc, sparc64, etc.).

# See Also

Check out [FFI::Platypus](https://metacpan.org/pod/FFI%3A%3APlatypus) 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 &lt;sanko@cpan.org&gt;
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