Puffy's Saga (ZX Spectrum)

Puffy's Saga
Developers: Ashminster Computing, Ubi Soft Publisher: Ubi Soft Platform: ZX Spectrum Released in EU: 1989 This game has uncompiled source code.

Sound Driver Source Code Fragment

Two pieces of code used for the sound driver in this game can be viewed with a hex editor at the addresses below for the .tzx dump.

313E:

          C HL
	CALL NZ,CHORD
	LD (IX+DATA),L
	LD (IX+DATA+1),H
ENVELOPE	
        INC (IX+ENVTIMER)
	LD A,(IX+ENVTIMER)
	CP ADTIME
	JR NC,$10
	LD E,(IX+ENVTIMER)
	LD HL,ATTACKDECAY-1
	JR $11
$10	SUB (IX+SUSTAIN)
	RET C
	LD E,A
	LD HL,RELEASE
$11	LD D,0
	ADD HL,DE
	LD E,(HL)
	LD BC,#FFFD
	LD A,(IX+CHANNELNUM)
	ADD 8
	OUT (C),A
	LD B,#BF
	OUT (C),E
	RET

ADTIME	EQU 6
RTIME	EQU 7

ATTACKDECAY	DB 13,12,11,10,9,8

RELEASE		DB 7,6,5,4,3,2,0

CHORD	PUSH IX

3348:

EQ
	LD A,(HL)
	INC HL
	CALL SET_LENGTH
	POP IX
	RET


SET_LENGTH
	LD C,%00100000
	RES 7,A
	BIT 3,A
	JR Z,$10
	RES 3,A
	LD C,%00110000
$10	LD B,A
	INC B
	DEC B
	JR Z,$11
$12	SRL C
	DJNZ $12
$11	LD A,C
	LD (IX+TIMER),A
	SUB RTIME
	JR NC,$13
	SUB A
$13	LD (IX+SUSTAIN),A
	LD (IX+ENVTIMER),0
	RET


SET_FREQ
	PUSH HL
	SUB #18
	LD BC,#000C
$10	INC