.MACRODEF LOAD_MUSIC =music_addr
	LD A, bank(=music_addr)
	LD ($mem_current_vgm_header), A
	LD A, high(ptr(=music_addr))
	LD ($mem_current_vgm_header+1), A
	LD A, low(ptr(=music_addr))
	LD ($mem_current_vgm_header+2), A
.END

Reset_Music_Channels:
	CALL =Reset_Music_Channel4
	CALL =Reset_Music_Channel3
	CALL =Reset_Music_Channel2

Reset_Music_Channel1:
	LD A, $00
	LD ($11), A
	LD ($12), A
	LD ($13), A
	LD ($14), A
	RET

Reset_Music_Channel2:
	LD A, $00
	LD ($16), A
	LD ($17), A
	LD ($18), A
	LD ($19), A
	RET

Reset_Music_Channel3:
	LD A, $00
	LD ($1A), A
	LD ($1B), A
	LD ($1C), A
	LD ($1D), A
	LD ($1E), A
	RET

Reset_Music_Channel4:
	LD A, $00
	LD ($20), A
	LD ($21), A
	LD ($22), A
	LD ($23), A
	RET

Start_Music:
	LD A, ($mem_current_vgm_header)
	.CHANGE_BANK_TO_A
	LD A, ($mem_current_vgm_header+1)
	LD H, A
	LD A, ($mem_current_vgm_header+2)
	LD L, A

	LD A, L
	ADD $34
	LD L, A
	LD A, H
	ADC $00
	LD H, A
	CALL =Fix_HL_Bank
	LD A, L
	ADD (HL)
	LD L, A
	LD A, H
	ADC $00
	LD H, A
	CALL =Fix_HL_Bank

	LD A, $saved_rom_bank
	LD ($mem_current_vgm_pc), A
	LD A, H
	LD ($mem_current_vgm_pc+1), A
	LD A, L
	LD ($mem_current_vgm_pc+2), A
	RET

Loop_Music:
	LD A, ($mem_current_vgm_header)
	.CHANGE_BANK_TO_A
	LD A, ($mem_current_vgm_header+1)
	LD H, A
	LD A, ($mem_current_vgm_header+2)
	LD L, A

	LD A, L
	ADD $1c
	LD L, A
	LD A, H
	ADC $00
	LD H, A
	CALL =Fix_HL_Bank
	LD B, H
	LD C, L
	LD A, $saved_rom_bank
	LD E, A

	LD A, B
	SUB $40
	LD B, A

	LD A, (HL)
	LD $tmp_var_1, A
	CALL =Inc_HL_Fix_Bank
	ADD C
	LD C, A
	LD A, (HL)
	LD $tmp_var_2, A
	CALL =Inc_HL_Fix_Bank
	ADC B
	LD B, A
	LD A, (HL)
	LD $tmp_var_3, A
	CALL =Inc_HL_Fix_Bank
	ADC E
	LD E, A

	LD A, $tmp_var_1
	CP $00
	JR NZ, =.end_check_empty
	LD A, $tmp_var_2
	CP $00
	JR NZ, =.end_check_empty
	LD A, $tmp_var_2
	CP $00
	JR Z, =Stop_music
	.end_check_empty:

	LD A, $00
	SLA B
	RL A
	ADD E
	LD E, A

	SRA B
	LD A, $40
	ADD B
	LD B, A

	LD A, E
	LD ($mem_current_vgm_pc), A
	LD A, B
	LD ($mem_current_vgm_pc+1), A
	LD A, C
	LD ($mem_current_vgm_pc+2), A
	RET

Stop_Music:
	LD A, $mem_sound_flags
	RES 0, A
	LD $mem_sound_flags, A
	LD A, $mem_sound_flags
	BIT 1, A
	CALL Z, =Reset_Music_Channel1
	LD A, $mem_sound_flags
	BIT 2, A
	CALL Z, =Reset_Music_Channel2
	LD A, $mem_sound_flags
	BIT 3, A
	CALL Z, =Reset_Music_Channel3
	LD A, $mem_sound_flags
	BIT 4, A
	CALL Z, =Reset_Music_Channel4
	RET

Inc_HL_Fix_Bank:
	PUSH AF
	INC HL
	CALL =Fix_HL_Bank
	POP AF
	RET

Fix_HL_Bank:
	LD A, H
	CP $80
	JR C, =.end
	SUB $40
	LD H, A

	LD A, $saved_rom_bank
	INC A
	.CHANGE_BANK_TO_A

	.end:
	RET

Check_Channel_Available:
	; TODO: Channel panning register in $FF25 is still impacted by music
	CP $24
	RET NC

	PUSH BC

	CP $1A
	JR NC =.channel_3_4
	.channel_1_2:
	CP $16
	JR NC, =.channel_2

	.channel_1:
	LD C, A
	LD A, $mem_sound_flags
	BIT 1, A
	LD A, C
	JR Z, =.end
	LD A, $00
	JR =.end

	.channel_2:
	LD C, A
	LD A, $mem_sound_flags
	BIT 2, A
	LD A, C
	JR Z, =.end
	LD A, $00
	JR =.end

	.channel_3_4:
	CP $20
	JR NC, =.channel_4

	.channel_3:
	LD C, A
	LD A, $mem_sound_flags
	BIT 3, A
	LD A, C
	JR Z, =.end
	LD A, $00
	JR =.end

	.channel_4:
	LD C, A
	LD A, $mem_sound_flags
	BIT 4, A
	LD A, C
	JR Z, =.end
	LD A, $00

	.end:
	POP BC
	RET

Play_Music:
	LD A, $mem_sound_flags
	BIT 0, A
	RET Z
	BIT 5, A
	JR Z, =.sound_effect_frame_count_dec_skip
		LD A, $mem_sound_effect_frame_count
		DEC A
		LD $mem_sound_effect_frame_count, A
		CP $00
		JR NZ, =.sound_effect_frame_count_dec_skip

		LD A, $mem_sound_flags
		AND 0b11000001
		LD $mem_sound_flags, A
	.sound_effect_frame_count_dec_skip:
	LD A, ($mem_current_vgm_pc)
	.CHANGE_BANK_TO_A
	LD A, ($mem_current_vgm_pc+1)
	LD H, A
	LD A, ($mem_current_vgm_pc+2)
	LD L, A

	.next:
	LD A, (HL)
	CALL =Inc_HL_Fix_Bank
	CP $b3
	JR NZ, =.set_register.end
	.set_register:
		LD A, (HL)
		CALL =Inc_HL_Fix_Bank
		LD C, A

		LD B, (HL)
		CALL =Inc_HL_Fix_Bank

		LD A, C
		ADD $10
		CALL =Check_Channel_Available
		CP $00
		JR Z, =.next
		LD C, A

		LD A, B
		LD (C), A
		JR =.next
	.set_register.end:

	CP $66
	JP Z, =Loop_Music


	CP $62
	JR Z, =.panic.end
	CP $61
	JR NZ, =.the61thingy.end
	.the61thingy:
	CALL =Inc_HL_Fix_Bank
	CALL =Inc_HL_Fix_Bank
	JR =.panic.end
	.the61thingy.end:

	.panic:
		LD A, $saved_rom_bank
		STOP
	.panic.end:

	LD A, H
	LD ($mem_current_vgm_pc+1), A
	LD A, L
	LD ($mem_current_vgm_pc+2), A
	LD A, $saved_rom_bank
	LD ($mem_current_vgm_pc), A
	RET