Chase H.Q.: Routine at 8A0F

8A0F: Cornering sound effect

The game only ever uses a duty factor of 100 and a count of 1.

Input
D	Duty factor and outer loop count
E	Inner loop count
Half	duty cycle: only run on every other call.

sfx_cornering

8A0F

LD A,$00

Toggle static flag

8A11

XOR $01

8A13

LD ($8A10),A

8A16

RET NZ

Return if flag became non-zero

sfx_cornering_loop_outer

8A17

LD C,E

Set inner loop counter

sfx_cornering_loop_inner

8A18

CALL rng

Call rng

8A1B

AND $10

Mask off bit 4

8A1D

JR Z,sfx_cornering_continue

If zero goto sfx_cornering_continue

Delay for (24 - D) iterations.

8A1F

LD A,$18

8A21

SUB D

8A22

LD B,A

sfx_cornering_delay1

8A23

DJNZ sfx_cornering_delay1

I'm unsure why they're setting both of the EAR and MIC bits here. Is it louder?

8A25

LD A,$18

Set EAR and MIC bits

8A27

OUT ($FE),A

Set output

Delay for D iterations.

8A29

LD B,D

sfx_cornering_delay2

8A2A

DJNZ sfx_cornering_delay2

8A2C

XOR A

Clear output

8A2D

OUT ($FE),A

sfx_cornering_continue

8A2F

DEC C

Loop while inner loop counter > 0

8A30

JR NZ,sfx_cornering_loop_inner

8A32

DEC D

Loop while duty factor > 0

8A33

JR NZ,sfx_cornering_loop_outer

8A35

RET

Return