MPU401_MODE_OUTPUT_TRIGGER
midi->mode[midi->output_mpu] &= ~MPU401_MODE_OUTPUT_TRIGGER;
midi->mode[mpu] &= ~MPU401_MODE_OUTPUT_TRIGGER;
if ((midi->mode[mpu] & MPU401_MODE_OUTPUT_TRIGGER) == 0) {
midi->mode[mpu] |= MPU401_MODE_OUTPUT_TRIGGER;
midi->mode[mpu] &= ~MPU401_MODE_OUTPUT_TRIGGER;