[LAD] Segfault when trying to dereference __midi_event.buffer (c++ newbie question)

[Harry van Haaren]

On Wed, Nov 21, 2012 at 11:54 AM, Shani Hadiyanto Pribadi <
shanipribadi at gmx.net> wrote:

> jack_midi_event_get(&in_event, midi_buf, event_index);
> if ((*(in_event.buffer) & 0xf0) == 0x90) // Segfault happens here, on
> boolean mask operation
> {
>     _note = *(in_event.buffer + 1);
> }
>

Extra context from you git repo:
    void *midi_buf;
    jack_midi_event_t in_event;
    jack_nframes_t event_index = 0;
    jack_nframes_t event_count;

    midi_buf = jack_port_get_buffer(_ports[MIDI], nframes);
    event_count = jack_midi_get_event_count(midi_buf);

    jack_midi_event_get(&in_event, midi_buf, event_index); // error here?
    std::cout << std::hex << static_cast<unsigned int> (*(in_event.buffer))
<< std::endl;
    if (event_count)
    {
    }

What happens when event_index has a value of 0? It will attempt a read &
dereference anyway.
Perhaps put the jack_midi_event_get() call into the if  statement.

Also, you should probably use this instead of if(event_count)

int event_num = 0;
while ( event_num < event_count )
{
   // do stuff
   event_num++;
}

Haven't tried the above code, but I think that might be it :)
HTH, -Harry
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