26 Jul
2006
26 Jul
'06
8:26 a.m.
On Wed, 26 Jul 2006, Clemens Ladisch wrote:
Ari Kauppi wrote:
Good try but it still has at least one potential problem: according to
MIDI spec running status should be set only with channel messages.
Sysex/common messages should reset it to undefined (0).
With this exact implementation it shouldn't cause any problems but if the
parser is extended/modified later it might become a pretty hard to find
bug with some input..
On Wed, 26 Jul 2006, Jens M Andreasen wrote:
Okay, here is my entry to the Official LAD MIDI Parser Contest 2006: 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.. 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;
}
}
}
--
Ari