dos33fsprogs/music/still_alive/sa_mb.s
Vince Weaver b1238af49d re-arranged the entire directory structure
this will probably upset people
2021-01-05 15:29:31 -05:00

282 lines
4.8 KiB
ArmAsm

; program is ~16k, so from 0xc00 to 0x4C00
UNPACK_BUFFER EQU $5E00 ; $5E00 - $9600, 14k, $3800
; trying not to hit DOS at $9600
; Reserve 3 chunks plus spare (14k)
still_alive_mb:
;=============================
; Setup
;=============================
; init variables
lda #0
sta DONE_PLAYING
sta MB_CHUNK_OFFSET
sta DECODE_ERROR
sta LYRICS_ACTIVE
; call mockingboard detect?
; ASSUME FOUND TO SAVE ROOM
; jsr mockingboard_detect_slot4 ; call detection routine
; cpx #$1
; beq mockingboard_found
; Not found.
; Print a message for debugging?
; jmp forever_loop ; and wait forever
mockingboard_found:
;============================
; Init the Mockingboard
;============================
jsr mockingboard_init
jsr reset_ay_both
jsr clear_ay_both
;=========================
; Setup Interrupt Handler
;=========================
; Vector address goes to 0x3fe/0x3ff
; FIXME: should chain any existing handler
lda #<interrupt_handler
sta $03fe
lda #>interrupt_handler
sta $03ff
;============================
; Enable 50Hz clock on 6522
;============================
sei ; disable interrupts just in case
lda #$40 ; Continuous interrupts, don't touch PB7
sta $C40B ; ACR register
lda #$7F ; clear all interrupt flags
sta $C40E ; IER register (interrupt enable)
lda #$C0
sta $C40D ; IFR: 1100, enable interrupt on timer one oflow
sta $C40E ; IER: 1100, enable timer one interrupt
lda #$E7
sta $C404 ; write into low-order latch
lda #$4f
sta $C405 ; write into high-order latch,
; load both values into counter
; clear interrupt and start counting
; 4fe7 / 1e6 = .020s, 50Hz
;==============================
; Setup lyrics
;==============================
; lda #<(lyrics)
; sta LYRICSL
; lda #>(lyrics)
; sta LYRICSH
;==================
; load song
;==================
jsr load_song
;============================
; Enable 6502 interrupts
;============================
cli ; clear interrupt mask
;============================
; Main Loop
;============================
main_loop:
lda DECODE_ERROR
beq check_copy
sei
brk ; panic if we had an error
check_copy:
lda COPY_TIME
beq check_decompress ; if zero, skip
lda #0
sta COPY_OFFSET
check_copy_loop:
jsr page_copy ;6+3621
inc COPY_OFFSET ; (opt: make subtract?) ; 5
lda #14 ; NOT HEX URGH!
cmp COPY_OFFSET
bne check_copy_loop
lda #0 ; we are done
sta COPY_TIME
check_decompress:
lda DECOMPRESS_TIME
beq check_done ; if zero, skip
jsr setup_next_subsong ; decompress
lda MB_CHUNK_OFFSET
sta TIME_TAKEN
lda #0
sta DECOMPRESS_TIME
check_done:
lda DONE_PLAYING
beq main_loop
forever_loop:
rts
;=================
; load our song
;=================
load_song:
;=========================
; Init Variables
;=========================
lda #$0
sta COPY_OFFSET
sta DECOMPRESS_TIME
sta COPY_TIME
sta MB_CHUNK_OFFSET
lda #$20
sta DECODER_STATE
lda #3
sta CHUNKSIZE
; We buffer one frame so start out one frame behind
lda #$ff
sta FRAME_COUNT
;===========================
; Setup KRW file
;===========================
; Point LZ4 src at proper place
ldy #0
lda #>(LZ4_BUFFER+3)
sta LZ4_SRC+1
lda #<(LZ4_BUFFER+3)
sta LZ4_SRC
lda (LZ4_SRC),Y ; get header skip
clc
adc LZ4_SRC
sta LZ4_SRC
lda LZ4_SRC+1
adc #0
sta LZ4_SRC+1
lda #<UNPACK_BUFFER ; set input pointer
sta INL
lda #>UNPACK_BUFFER
sta INH
; Decompress first chunks
lda #$0
sta COPY_OFFSET
sta DECOMPRESS_TIME
lda #$3
sta CHUNKSIZE
lda #$20
sta DECODER_STATE
sta COPY_TIME
jsr setup_next_subsong
rts
;=================
; next sub-song
;=================
setup_next_subsong:
ldy #0
lda (LZ4_SRC),Y ; get next size value
sta LZ4_END
iny
lda (LZ4_SRC),Y
sta LZ4_END+1
lda #2 ; increment pointer
clc
adc LZ4_SRC
sta LZ4_SRC
lda LZ4_SRC+1
adc #0
sta LZ4_SRC+1
jsr lz4_decode ; decode
; tail-call?
rts
;==============================================
; plan: takes 256 50Hz to play a chunk
; need to copy 14 256-byte blocks
; PLAY A (copying C)
; PLAY B (copying C)
; PLAY D (decompressing A/B/C)
;========================
; page copy
;========================
; want to copy:
; SRC: chunk_buffer+(2*256)+(COPY_OFFSET*3*256)
; DST: chunk_buffer+$2A00+(COPY_OFFSET*256)
page_copy:
clc ; 2
lda #>(UNPACK_BUFFER+512) ; 3
adc COPY_OFFSET ; 3
adc COPY_OFFSET ; 3
adc COPY_OFFSET ; 3
sta page_copy_loop+2 ; self modify ; 5
lda #>(UNPACK_BUFFER+$2A00) ; 2
adc COPY_OFFSET ; 3
sta page_copy_loop+5 ; self modify ; 5
ldx #$00 ; 2
page_copy_loop:
lda $1000,x ; 4
sta $1000,X ; 5
inx ; 2
bne page_copy_loop ; 2nt/3
rts ; 6
;======================
; 2+14*256+6+29= 3621