Re: Problem where a function is invoked once but called twice (when invocation is within an allocator).

[Georg Bauhaus <rm.dash-bauhaus@futureapps.de>]

On 5/7/11 3:38 AM, Rod Kay wrote:

>     I'm using the GPL10 edition of Gnat on Ubuntu 10.04 (32bit).
>
>     Here's a tarball of the testcase ... http://109.74.196.91:8080/double_next_frame_call.tar.gz
>
>     You may need to install ffmpeg development packages (libavutil-dev,
> libswscale-dev, libavcodec-dev, libavformat-dev on debian/ubuntu).
>
>     Also, it should be built with gprbuild.

First, I can confirm that on Mac OS X the assembly listing
of tester shows three calls, too:

$ grep _media__video__next_frame build/tester.s
	call	_media__video__next_frame
	call	_media__video__next_frame
	call	_media__video__next_frame
$

(I've had to make a few changes to c_media due to recent
changes in ffmpeg, viz. definitions CODEC_TYPE_VIDEO and
others seem to have been replaced with AVMEDIA_TYPE_VIDEO
and others; avcodec_decode_video2 is new for
avcodec_decode_video. Just grabbed patches from ffmpeg
clients from the net, I don't understand them.)

The following appears to be generating two calls only, FWIW:

    the_Movie : media.Video.view := media.Video.new_Video ("xyz.avi");

    Case_1 :        openGL.Image := the_Movie.next_Frame;
    Workaround :    openGL.Image renames The_Movie.Next_Frame;
    Case_2 : access openGL.Image := new opengl.Image' (Workaround);
  
$ grep _media__video__next_frame build/tester.s
	call	_media__video__next_frame
	call	_media__video__next_frame
$