Gyruss: Routine at 9C7E

9C7E: End of processing sound channel

Used by the routine at L9C4B.
L9C7E	9C7E	LD E,(IX+$08)	Copy byte 8 (speed) to countdown
	9C81	LD (IX+$07),E	...
	9C84	OR (IX+$06)	Get attenuation from byte 6
This entry point is used by the routine at L9C4B.
L9C7E_0	9C87	LD (IX+$04),A	Save in attenuation/frequency
This entry point is used by the routines at L9BFD, process_tune_byte and L9C4B.
next_tune_data_buffer	9C8A	LD DE,$000A	Next tune data buffer
	9C8D	ADD IX,DE	...
	9C8F	DJNZ process_tune_byte	Loop for 4 channels
	9C91	RET