Chase H.Q.: Routine at EF22

EF22: Drum sample player

Used by the routine at play_music_48k.

Input
A	Calling this <speed value> (8/3/1 seem to be the used values in practice)

playdrum_2

EF22

LD HL,$F05A

Address of drum 2 data

EF25

LD D,$6C

108 sample bytes

EF27

JR pd_start

Jump to pd_start

This entry point is used by the routine at play_music_48k.

playdrum_1

EF29

LD HL,$EF5E

Address of drum 1 data

EF2C

LD D,$FC

252 sample bytes

This modifies the number of bits of each sample byte that is output.

pd_start

EF2E

LD ($EF3A),A

Self modify 'LD B' @ pd_go <speed value> to be A as passed in

EF31

LD A,$01

Self modify 'LD A' @ pm_start_drums <drum is playing flag> to be 1

EF33

LD ($EF0E),A

EF36

JR pd_go

Jump to pd_go

This entry point is used by the routine at play_music_48k.

pd_bank_go

EF38

EXX

Bank

Output a byte.

pd_go

EF39

LD B,$08

<speed value> iterations -- Self modified by pd_start (sampled: 8, 3, 1)

pd_loop

EF3B

LD A,$10

Set speaker flag

EF3D

NOP

Delay

EF3E

BIT 7,(HL)

Test a sample bit

EF40

JR NZ,pd_output_bit

Set speaker flag to match sample bit

EF42

RES 4,A

pd_output_bit

EF44

OUT ($FE),A

Output it

EF46

RLC (HL)

Rotate sample byte in-place

EF48

DJNZ pd_loop

Loop to pd_loop while B

EF4A

INC HL

Move to next sample byte

EF4B

DEC D

Decrement sample bytes remaining

EF4C

JR Z,pd_end_of_sample

Jump to pd_end_of_sample if no bytes remain

EF4E

LD A,($EF14)

Read A from 'LD A' @ pm_wait_for_interrupt -- <interrupt flag>

EF51

AND A

Set flags

EF52

JP Z,pd_go

Loop to pd_go if clear

EF55

EXX

Otherwise unbank

EF56

RET

Return

pd_end_of_sample

EF57

XOR A

Self modify 'LD A' @ pm_start_drums <drum is playing flag> to be 0 -- zeroed when playing stops

EF58

LD ($EF0E),A

EF5B

JP pm_wait_for_interrupt

Jump to pm_wait_for_interrupt

drum1

EF5E

DEFB $FF,$00,$00,$00,$0F,$FF,$FF,$FF

Drum 1 sample/data

EF66

DEFB $EF,$FF,$FF,$FF,$BE,$36,$10,$00

EF6E

DEFB $00,$00,$00,$00,$00,$00,$00,$00

EF76

DEFB $00,$FF,$FF,$FF,$FF,$FF,$FF,$FF

EF7E

DEFB $FF,$FF,$FF,$FF,$FF,$F8,$78,$80

EF86

DEFB $00,$00,$00,$00,$00,$00,$00,$00

EF8E

DEFB $00,$C0,$E1,$FF,$FF,$FF,$FF,$FF

EF96

DEFB $FF,$FF,$FF,$FF,$FF,$BE,$F3,$9E

EF9E

DEFB $70,$C0,$00,$00,$00,$00,$00,$00

EFA6

DEFB $01,$9E,$FF,$3F,$FF,$FF,$FF,$FF

EFAE

DEFB $FF,$FF,$FF,$FF,$FF,$FB,$FF,$3F

EFB6

DEFB $38,$F0,$03,$80,$00,$00,$00,$00

EFBE

DEFB $00,$00,$C6,$DB,$9D,$FF,$FF,$FF

EFC6

DEFB $FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF

EFCE

DEFB $FF,$FE,$07,$70,$60,$00,$00,$00

EFD6

DEFB $01,$00,$00,$08,$80,$77,$DF,$FF

EFDE

DEFB $FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF

EFE6

DEFB $FE,$FF,$F8,$A3,$CE,$1C,$64,$02

EFEE

DEFB $20,$00,$0E,$00,$00,$3F,$18,$8F

EFF6

DEFB $9F,$FF,$FF,$DF,$FF,$FF,$FF,$FF

EFFE

DEFB $FF,$EF,$FF,$FF,$EF,$FF,$3F,$FC

F006

DEFB $9C,$38,$CE,$00,$03,$00,$00,$00

F00E

DEFB $C4,$7F,$01,$FF,$FF,$FF,$FF,$FF

F016

DEFB $FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF

F01E

DEFB $3E,$40,$98,$10,$C0,$1F,$80,$00

F026

DEFB $FF,$00,$1F,$FF,$7F,$FF,$FF,$FF

F02E

DEFB $FF,$FF,$FF,$FF,$FF,$FF,$B8,$77

F036

DEFB $7E,$FC,$FE,$7F,$E7,$6F,$DE,$FF

F03E

DEFB $FE,$07,$F9,$FF,$3B,$3F,$3F,$FE

F046

DEFB $DF,$FF,$FF,$EF,$FF,$FF,$FF,$FF

F04E

DEFB $FF,$FF,$03,$FE,$FF,$33,$A7,$FF

F056

DEFB $9F,$FF,$EF,$00

drum2

F05A

DEFB $FF,$FF,$FF,$FF,$FF,$F3,$F8,$30

Drum 2 sample/data

F062

DEFB $FF,$DE,$00,$FF,$81,$FF,$FF,$FF

F06A

DEFB $FF,$FF,$FF,$FF,$FF,$F4,$3B,$80

F072

DEFB $00,$00,$00,$00,$00,$3C,$00,$00

F07A

DEFB $00,$00,$1B,$FF,$FF,$FF,$FF,$FF

F082

DEFB $FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF

F08A

DEFB $FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF

F092

DEFB $FF,$FF,$E0,$00,$00,$00,$00,$00

F09A

DEFB $00,$00,$00,$00,$00,$00,$00,$00

F0A2

DEFB $00,$00,$00,$00,$7F,$FF,$FF,$FF

F0AA

DEFB $FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF

F0B2

DEFB $FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF

F0BA

DEFB $FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF

F0C2

DEFB $FF,$FD,$7E,$00