Puffy's Saga (ZX Spectrum)

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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