UNSET_CHANNELMASK(channel[to_ch].channel_layer, to_ch); 
void add_channel_layer(int to_ch, int from_ch){	if (to_ch >= MAX_CHANNELS || from_ch >= MAX_CHANNELS)		return;	/* add a channel layer */	SET_CHANNELMASK(channel[to_ch].channel_layer, from_ch);	UNSET_CHANNELMASK(channel[to_ch].channel_layer, to_ch);	ctl->cmsg(CMSG_INFO, VERB_NOISY,			"Channel Layer (CH:%d -> CH:%d)", from_ch, to_ch);}
4357	/local/tlutelli/issta_data/temp/c/2005_temp/2005/4357/a3135fbbbe2a9f9ae5052cafe459751a9736d252/readmidi.c/buggy/timidity/readmidi.c