TRIGGER_CHANNEL_0
snd_emu10k1x_ptr_write(emu, TRIGGER_CHANNEL, 0, snd_emu10k1x_ptr_read(emu, TRIGGER_CHANNEL, 0)|(TRIGGER_CHANNEL_0<<channel));
snd_emu10k1x_ptr_write(emu, TRIGGER_CHANNEL, 0, snd_emu10k1x_ptr_read(emu, TRIGGER_CHANNEL, 0) & ~(TRIGGER_CHANNEL_0<<channel));