http://qs321.pair.com?node_id=1167999


in reply to Re^2: Passing integer pointer in XS? (&)
in thread Passing integer pointer in XS?

So, you'll need to add just a bit more: 

int
tdSensor(protocol, protocolLen, model, modelLen, id, dataTypes)
        char *  protocol
        int     protocolLen
        char *  model
        int     modelLen
        int &   id
        int &   dataTypes
CODE:
    RETVAL = tdSensor(protocol, protocolLen, model, modelLen, &id, &da
+taTypes);
OUTPUT:
    RETVAL
    id
    dataTypes

[download]

Sorry, it has been many years since I learned this stuff.

- tye        

Replies are listed 'Best First'.
Re^4: Passing integer pointer in XS? (OUTPUT:)
by ikegami (Patriarch) on Jul 18, 2016 at 21:38 UTC

    Problem: You can't write to protocol or model safely because one of the force functions wasn't used. You might end up changing variables and constants you didn't mean to change. (They might have fixed that in 5.24?) 

    use strict;
use warnings;

use feature qw( say );

use Inline C => <<'__EOS__';

   void testing(char* s) {
      s[0] = 'y';
   }

__EOS__

my $x = "x";
my $y = $x;
say "$x-$y";
testing($y);
say "$x-$y";

    [download]
    x-x
y-y   <-- Changed both $x and $y

    [download]
    or 
    for (1..2) {
   my $y = "x";
   say $y;
   testing($y);
}

    [download]
    x
y     <-- Changed the constant!

    [download]

    Note: The caller will need to do s/\0.*// for $protocol, $model;

[reply]
[d/l]
[select]

      I suspect that those "char *" arguments are treated such that they could be "const char *" arguments. I also suspect that "\0" characters are not expected. But if I am wrong then, yes, you need to do more work than I did. Thanks.

      - tye        

[reply]

        And thank you for showing me int &. It's not valid C, but apparently it's valid XS. I did not know that.

[reply]
[d/l]
Re^4: Passing integer pointer in XS? (OUTPUT:)
by martin67 (Novice) on Jul 18, 2016 at 21:04 UTC
    Thank you!

    This also works! (I got another variant further down in the thread.)

    This was my first question to Perlmonks and I'm impressed by the speed and quality of the answers!

[reply]

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