Chase H.Q.: Routine at 89D9

89D9: "Thud" sound effect

The game uses a delay multiplier of 8 for car landings and 3 for hazard hits.

Input
D	Delay multiplier value

sfx_thud

89D9

LD C,$20

Length of table is 32

89DB

LD HL,$89EF

Point HL at the effect data table

89DE

XOR A

Zero output byte

sfx_thud_loop

89DF

LD B,(HL)

Read a byte (a delay)

sfx_thud_output

89E0

OUT ($FE),A

Output

89E2

LD E,D

Delay/hold for D iterations

sfx_thud_delay

89E3

DEC E

89E4

JR NZ,sfx_thud_delay

This will jump back and re-do the OUT again, but A will not have changed value in the meanwhile... however it might be this way for timing reasons.

89E6

DJNZ sfx_thud_output

Loop for B iterations

89E8

XOR $10

Toggle the EAR bit

89EA

INC HL

Advance to next effect data byte

89EB

DEC C

Loop until out of effect data

89EC

JR NZ,sfx_thud_loop

89EE

RET

Return

sfx_thud_table

89EF

DEFB $02,$07,$05,$02,$04,$0A,$01,$04

Each byte is a delay between speaker toggles (off-on-off-...)

89F7

DEFB $09,$09,$06,$45,$01,$01,$04,$03

89FF

DEFB $01,$03,$31,$04,$25,$02,$01,$BD

8A07

DEFB $8E,$ED,$01,$01,$01,$06,$07,$01