dos33fsprogs/games/lemm/audio.s
2022-03-15 16:37:02 -04:00

205 lines
4.0 KiB
ArmAsm

; Based on BTC.SYSTEM by Oliver Schmidt
; How to generate proper audio for this:
; -Open MP3 in Audacity
; -Change Project Rate (Hz) to 33,000 (bottom left box)
; -Tracks --> Mix... --> Mix Stereo Down to Mono
; -File --> Export --> Export as WAV
; - Select "WAV (Microsoft) signed 16-bit PCM"
; - Under "Edit Metadata Tags" hit "Clear", then "Okay"
; -Open saved WAV file in BTc Sound Encoder 3.0
; -Change Algorithm to "1 bit" (leave fineness as BTc16)
; -File --> Export binary file .BTC format
spkr = $C030
;****************************************************************
;* Audio playback *
;****************************************************************
; audio file in BTC_L/BTC_H
; pages to play in X
play_audio:
ldy #0
; loop here as long as BITs are [F]alse (aka 0)
F_NX: NOP ; 2 2
NOP ; 2 2
NOP ; 2 2
BIT $00 ; 3 3
F_RD: LDA (BTC_L),y ; 5 5 5
ASL ; 2 2 2
BCS T_1_SW ; 2/3 2
NOP ; 2 2
NOP ; 2 2
NOP ; 2 2
NOP ; 2 2
F_1: JSR delay ; 6 (+13) 19
ASL ; 2 2 = 31
BCS T_2_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
F_2: JSR delay ; 6 (+13)
ASL ; 2
BCS T_3_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
F_3: JSR delay ; 6 (+13)
ASL ; 2
BCS T_4_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
F_4: JSR delay ; 6 (+13)
ASL ; 2
BCS T_5_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
F_5: JSR delay ; 6 (+13)
ASL ; 2
BCS T_6_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
F_6: JSR delay ; 6 (+13)
ASL ; 2
BCS T_7_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
F_7: JSR delay ; 6 (+13)
ASL ; 2
BCS T_8_SW ; 2/3 2 2
NOP ; 2 2 2
NOP ; 2 2 2
NOP ; 2 2 2
NOP ; 2 2 2
F_8: INY ; 2 2 2
BNE F_NX ; 2/3 3 = 31 2
INC BTC_H ; 5 5
DEX ; 2 2
BNE F_RD ; 2/3 3 = 31
RTS
; click speaker on transitions
T_1_SW: STA spkr ; 4 [SW]itch to [T]rue on BIT [1]
BCS T_1 ; 3 (always)
T_2_SW: STA spkr ; 4 [SW]itch to [T]rue on BIT [2]
BCS T_2 ; 3 (always)
T_3_SW: STA spkr ; 4 [SW]itch to [T]rue on BIT [3]
BCS T_3 ; 3 (always)
T_4_SW: STA spkr ; 4 [SW]itch to [T]rue on BIT [4]
BCS T_4 ; 3 (always)
T_5_SW: STA spkr ; 4 [SW]itch to [T]rue on BIT [5]
BCS T_5 ; 3 (always)
T_6_SW: STA spkr ; 4 [SW]itch to [T]rue on BIT [6]
BCS T_6 ; 3 (always)
T_7_SW: STA spkr ; 4 [SW]itch to [T]rue on BIT [7]
BCS T_7 ; 3 (always)
T_8_SW: STA spkr ; 4 [SW]itch to [T]rue on BIT [8]
BCS T_8 ; 3 (always)
F_1_SW: STA spkr ; 4 [SW]itch to [F]alse on BIT [1]
BCC F_1 ; 3 (always)
F_2_SW: STA spkr ; 4 [SW]itch to [F]alse on BIT [2]
BCC F_2 ; 3 (always)
F_3_SW: STA spkr ; 4 [SW]itch to [F]alse on BIT [3]
BCC F_3 ; 3 (always)
F_4_SW: STA spkr ; 4 [SW]itch to [F]alse on BIT [4]
BCC F_4 ; 3 (always)
F_5_SW: STA spkr ; 4 [SW]itch to [F]alse on BIT [5]
BCC F_5 ; 3 (always)
F_6_SW: STA spkr ; 4 [SW]itch to [F]alse on BIT [6]
BCC F_6 ; 3 (always)
F_7_SW: STA spkr ; 4 [SW]itch to [F]alse on BIT [7]
BCC F_7 ; 3 (always)
F_8_SW: STA spkr ; 4 [SW]itch to [F]alse on BIT [8]
BCC F_8 ; 3 (always)
; loop here as long as BITs are [T]rue (aka 1)
T_NX: NOP ; 2
NOP ; 2
NOP ; 2
BIT $00 ; 3
T_RD: LDA (BTC_L),y ; 5
ASL ; 2
BCC F_1_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
T_1: JSR delay ; 6 (+13)
ASL ; 2
BCC F_2_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
T_2: JSR delay ; 6 (+13)
ASL ; 2
BCC F_3_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
T_3: JSR delay ; 6 (+13)
ASL ; 2
BCC F_4_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
T_4: JSR delay ; 6 (+13)
ASL ; 2
BCC F_5_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
T_5: JSR delay ; 6 (+13)
ASL ; 2
BCC F_6_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
T_6: JSR delay ; 6 (+13)
ASL ; 2
BCC F_7_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
T_7: JSR delay ; 6 (+13)
ASL ; 2
BCC F_8_SW ; 2/3
NOP ; 2
NOP ; 2
NOP ; 2
NOP ; 2
T_8: INY ; 2
BNE T_NX ; 2/3
INC BTC_H ; 5
DEX ; 2
BNE T_RD ; 2/3
RTS
delay:
nop ; 2
nop ; 2
BIT $00 ; 3
RTS ; 6 = 13