Gyruss: Routine at 9B0D

9B0D: Play tune

Used by the routines at L9BD9, process_tune_byte and call_play_tune.

Input
A	Index of tune (0 - 6)

play_tune

9B0D

CP $07

If tune index is 7

9B0F

JR Z,play_tune_0

Then skip ahead

9B11

LD (tune_index),A

Else save tune index

9B14

LD HL,$7284

tune_data_buffer_1+7

9B17

LD (HL),$02

Set to 2

play_tune_0

9B19

RLCA

Multiply index by 8

9B1A

RLCA

...

9B1B

RLCA

...

9B1C

LD E,A

DE = A

9B1D

LD D,$00

...

9B1F

LD HL,tune_data_table

Table base address

9B22

ADD HL,DE

Add offset

9B23

LD IX,tune_data_buffer_1

First tune data buffer

9B27

LD B,$04

4 channels

9B29

LD E,$0A

10 bytes each

play_tune_1

9B2B

LD A,(HL)

Get LSB

9B2C

LD (IX+$01),A

Store in tune data buffer

9B2F

INC HL

Next table address

9B30

LD A,(HL)

Get MSB

9B31

LD (IX+$02),A

Store in tune data buffer

9B34

LD (IX+$05),$01

Set countdown

9B38

INC HL

Next table address

9B39

LD (IX+$09),$00

Countdown for relative jumps

9B3D

ADD IX,DE

Next channel

9B3F

DJNZ play_tune_1

Loop for 4 channels

9B41

LD A,$05

Tune speed?

9B43

LD (sound_player_countdown),A

Init countdown

9B46

LD (is_tune_playing),A

Set a tune is playing

9B49

LD A,(tune_index)

Get tune index

9B4C

DEC A

Minus 1

9B4D

JR Z,play_tune_2

If tune index was 1 then skip ahead and set C = 9

9B4F

RET P

If tune index was > 1 then return

9B50

LD C,$05

Set C = 5 (sound index)

9B52

Skip next

play_tune_2

9B54

LD C,$09

Set C = 9 (sound index)

play_tune_3

9B56

JP play_sound_fx_2

Play sound