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|
; Sounds for Taipan! Atari 800 port.
; Made by capturing the Apple II audio and taking wild guesses,
; then refining them.
; I'm not shooting for Atari sounds that are identical to the
; Apple ones: (a) it's impossible anyway, and (b) the Apple
; sounds are a bit harsh to the ear. Hopefully these sound
; a little smoother while still being pretty close.
; This is an asm rewrite of sounds.c. Sounds the same, but weighs
; in at 186 bytes less code
; general form from sounds.c:
; for(j=0; j<repeats; j++) {
; for(i=0; i<Yreg; i++) {
; POKEY_WRITE.audf1 = Areg-i*Xreg;
; jsleep(delay);
; }
; }
.include "atari.inc"
.import _jsleep
.export _bad_joss_sound, _good_joss_sound, _under_attack_sound
.importzp tmp1, tmp2, tmp3, tmp4, sreg
initialpitch = sreg
delay = sreg+1
pitch = tmp1
decrement = tmp2
counter = tmp3
repeats = tmp4
; this must agree with newtitle.s
; 0 = enabled, 1 = disabled
sound_disabled = $06ff
_under_attack_sound:
; C version was:
; for(j=0; j<3; j++) {
; for(i=0; i<3; i++) {
; POKEY_WRITE.audf1 = 20-i*3;
; jsleep(3);
; }
; }
lda #$03
sta delay
sta repeats
tax
tay
lda #$14
; fall through to make_sound
; call make_sound with:
; A = initial pitch
; X = decrement amount per frame
; Y = inner loop count (i)
; repeats = outer loop count (j)
; delay = jiffies to delay per inner loop
make_sound:
sta initialpitch
stx decrement
sty counter
; if sound is disabled, don't play it at all.
lda sound_disabled
bne stop_sound
; init sound
lda #0
sta AUDCTL
lda #3
sta SKCTL
lda #$AA ; pure tone, volume 10
sta AUDC1
@repeatloop:
ldy counter
lda initialpitch
sta pitch
@noteloop:
lda pitch
sta AUDF1
sec
sbc decrement
sta pitch
ldx #0
lda delay
jsr _jsleep
; if user pressed a key, abort the sound entirely.
; disabled for now.
;lda CH
;cmp #$FF
;bne stop_sound
dey
bne @noteloop
dec repeats
bne @repeatloop
stop_sound:
lda #0
sta AUDC1
rts
_bad_joss_sound:
; C version was:
; for(i=0; i<10; i++) {
; POKEY_WRITE.audf1 = 80-i*8;
; jsleep(1);
; }
; which writes 80 72 64 56 48 40 32 24 16 8 to AUDF1
lda #$01
sta repeats
sta delay
lda #$50
ldx #$08
ldy #$0a
bne make_sound
_good_joss_sound:
; C version was:
; for(j=0; j<3; j++) {
; for(i=0; i<4; i++) {
; POKEY_WRITE.audf1 = 20-i*5;
; jsleep(2);
; }
; }
; which writes 20 15 10 5 to AUDF1, 3 times
lda #$03
sta repeats
lda #$02
sta delay
lda #$14
ldx #$05
ldy #$04
bne make_sound
|
