Implementing PTReplay PTSongPattern

[FlynnTheAvatar]

Hi,

I am currently trying to implement PTSongPattern in Fredrik Wikstrom's ptreplay library for AmigaOS 4.1.

I peaked (=disassembled) the m68k version of it (6.6) and came up this this naive implementation:

UBYTE _PTReplay_PTSongPattern(struct PTReplayIFace *Self,
 struct Module *module, UWORD Pos)
{
    dbug(("ptreplay::PTSongPattern\n"));

    UBYTE* p = (UBYTE *) module->file_data;
    if (Pos <= module->file_size) {
        return p[952 + Pos];
    }

 return (UBYTE)0;
}

Sorry, I have no idea about the library or the ProTracker file format. Does this suffice, or do I need to aquire the mutex before peeing into the loaded file?

Any help would be greatly appreciated.

Thanks,
Flynn

[phx]

Should be ok. The "song arrangement list" with all pattern-numbers is indeed at offset 952. Those are constants which should never change, so you can read them any time.

Although there is a maximum of 128 positions, so I would better check

Pos

against 128 instead of the module's file size.

[FlynnTheAvatar]

Thank you very much. The information that there are max 128 positions is really helpful. I updated the code with your suggestion and I am testing the new library at the moment.