| Win32::API::Callback - Callback support for Win32::API |
Win32::API::Callback - Callback support for Win32::API
use Win32::API; use Win32::API::Callback;
my $callback = Win32::API::Callback->new(
sub { my($a, $b) = @_; return $a+$b; },
"NN", "N",
);
Win32::API->Import(
'mydll', 'two_integers_cb', 'KNN', 'N',
);
$sum = two_integers_cb( $callback, 3, 2 );
Win32::API::Callback uses a subset of the type letters of Win32::API. C Prototype interface isn't supported. Not all the type letters of Win32::API are supported in Win32::API::Callback.
I:
value is an unsigned integer (unsigned int)i:
value is an signed integer (signed int or int)N:
value is a unsigned pointer sized number (unsigned long)n:
value is a signed pointer sized number (signed long or long)Q:
value is a unsigned 64 bit integer number (unsigned long long, unsigned __int64)
See next item for details.q:
value is a signed 64 bit integer number (long long, __int64)
If your perl has 'Q'/'q' quads support for the pack manpage then Win32::API's 'q'
is a normal perl numeric scalar. All 64 bit Perls have quad support. Almost no
32 bit Perls have quad support. On 32 bit Perls, without quad support,
Win32::API::Callback's 'q'/'Q' letter is a packed 8 byte string.
So 0x8000000050000000 from a perl with native Quad support
would be written as "\x00\x00\x00\x50\x00\x00\x00\x80" on a 32 bit
Perl without Quad support. To improve the use of 64 bit integers with
Win32::API::Callback on a 32 bit Perl without Quad support, there is
a per Win32::API::Callback object setting called UseMI64 in the Win32::API manpage
that causes all quads to be accepted as, and returned as the Math::Int64 manpage
objects. 4 to 8 byte long pass by copy/return type C aggregate types
are very rare in Windows, but they are supported as ``in'' and return
types by using 'q'/'Q' on 32 and 64 bits. Converting between the C aggregate
and its representation as a quad is up to the reader. For ``out'' in
Win32::API::Callback (not ``in''), if the argument is a reference, it will
automatically be treated as a Math::Int64 object without having to
previously call this function.F:
value is a floating point number (float)D:
value is a double precision number (double)Unimplemented types:
Unimplemented in Win32::API::Callback types such as shorts, chars, and
smaller than ``machine word size'' (32/64bit) numbers can be processed
by specifying N, then masking off the high bytes.
For example, to get a char, specify N, then do $numeric_char = $_[2] & 0xFF;
in your Perl callback sub. To get a short, specify N, then do
$numeric_char = $_[2] & 0xFFFF; in your Perl callback sub.
$CallbackObj = Win32::API::Callback->new( sub { print "hello world";},
'NDF', 'Q', '__cdecl');
$CallbackObj = Win32::API::Callback->new( sub { print "hello world";},
$in, $out);
Creates and returns a new Win32::API::Callback object. Calling convention parameter is optional. Calling convention parameter has same behaviour as Win32::API's calling convention parameter. C prototype parsing of Win32::API is not available with Win32::API::Callback. If the C caller assumes the callback has vararg parameters, and the platform is 64 bits/x64, in the first 4 parameters, if they are floats or doubles they will be garbage. Note there is no way to create a Win32::API::Callback callback with a vararg prototype. A workaround is to put ``enough'' Ns as the in types, and stop looking at the @_ slices in your Perl sub callback after a certain count. Usually the first parameter will somehow indicate how many additional stack parameters you are receiving. The Ns in @_ will eventually become garbage, technically they are the return address, saved registers, and C stack allocated variables of the caller. They are effectivly garbage for your vararg callback. All vararg callbacks on 32 bits must supply a calling convention, and it must be '__cdecl' or 'WINAPIV'.
See UseMI64 in the Win32::API manpage.
the Win32::API::Callback::IATPatch manpage
Aldo Calpini ( dada@perl.it ). Daniel Dragan ( bulkdd@cpan.org ).
Cosimo Streppone ( cosimo@cpan.org ).
| Win32::API::Callback - Callback support for Win32::API |