Re: [linux-audio-dev] Basic MIDI question

Ari Kauppi wrote:
> On Wed, 26 Jul 2006, Jens M Andreasen wrote:
>
> > if(runningStatus == NOTE_ON || runningStatus == NOTE_OFF)
>
> If you plan to receive messages from other channels than 0 you have to
> use (runningStatus & 0xF0) instead of the full runningStatus and perhaps
> check for (runningStaus & 0x0F) == receiveChannel..

Okay, here is my entry to the Official LAD MIDI Parser Contest 2006:

void handleByte(u8 byte)
{
        /* in a driver, these static variables should go into some struct: */
        static enum {
                STATE_UNKNOWN, /* not a note command */
                STATE_NOTE1, /* expecting 1st data byte (note) */
                STATE_NOTE2, /* expecting 2nd data byte (velocity) */
        } state = STATE_UNKNOWN;
        static u8 command;
        static u8 note;

        if (byte >= 0xf8) /* real-time command */
                ;
        else if (byte & 0x80) { /* status byte */
                command = byte;
                /* note-on or note-off? */
                state = (byte & 0xf0) <= 0x90 ? STATE_NOTE1 : STATE_UNKNOWN;
        } else { /* data byte */
                if (state == STATE_NOTE1) {
                        note = byte;
                        state = STATE_NOTE2;
                } else if (state == STATE_NOTE2) {
                        if ((command & 0xf0) == 0x90 && byte > 0) {
                                /* note on */
                        } else {
                                /* note off */
                        }
                        state = STATE_NOTE1;
                }
        }
}

Regards,
Clemens
Received on Wed Jul 26 12:15:06 2006