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dos33fsprogs/chiptune_player/chiptune_player.s

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; VMW Chiptune Player
.include "zp.inc"
LZ4_BUFFER EQU $2000 ; 16k for now, FIXME: expand
CHUNK_BUFFER EQU $6000 ; 10.5k, $2A00
CHUNKSIZE EQU $3
;=============================
; Setup
;=============================
jsr HOME
jsr TEXT
; init variables
lda #0
sta DRAW_PAGE
sta CH
sta CV
sta DONE_PLAYING
sta XPOS
sta MB_FRAME_DIFF
; print detection message
lda #<mocking_message ; load loading message
sta OUTL
lda #>mocking_message
sta OUTH
jsr move_and_print ; print it
jsr mockingboard_detect_slot4 ; call detection routine
cpx #$1
beq mockingboard_found
lda #<not_message ; if not found, print that
sta OUTL
lda #>not_message
sta OUTH
inc CV
jsr move_and_print
jmp forever_loop ; and wait forever
mockingboard_found:
; lda #<found_message ; print found message
; sta OUTL
; lda #>found_message
; sta OUTH
; inc CV
; jsr move_and_print
;============================
; 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
;============================
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
;============================
; Draw title screen
;============================
jsr set_gr_page0
lda #$4
sta DRAW_PAGE
jsr clear_screens
lda #<chip_title
sta GBASL
lda #>chip_title
sta GBASH
; Load image
lda #<$400
sta BASL
lda #>$400
sta BASH
jsr load_rle_gr
;===========================
; load first song
;===========================
jsr new_song
lda #<CHUNK_BUFFER ; set input pointer
sta INL
lda #>CHUNK_BUFFER
sta INH
;============================
; Enable 6502 interrupts
;============================
cli ; clear interrupt mask
;============================
; Init Background
;============================
; jsr clear_screens ; clear top/bottom of page 0/1
jsr set_gr_page0
lda #0
sta DRAW_PAGE
sta SCREEN_Y
;============================
; Loop forever
;============================
playing_loop:
;============================
; rasters
;============================
jsr clear_top
jsr draw_rasters
jsr volume_bars
jsr page_flip
lda DONE_PLAYING
beq playing_loop
done_play:
; FIXME: disable timer on 6522
; FIXME: unhook interrupt handler
sei ; disable interrupts
jsr clear_ay_both
lda #0
sta CH
jsr clear_bottoms
lda #21
sta CV
lda #<done_message
sta OUTL
lda #>done_message
sta OUTH
jsr print_both_pages
forever_loop:
jmp forever_loop
;=============================
;=============================
; simple interrupt handler
;=============================
;=============================
; On Apple II/6502 the interrupt handler jumps to address in 0xfffe
; This is in the ROM, which saves the registers
; on older IIe it saved A to $45 (which could mess with DISK II)
; newer IIe doesn't do that.
; It then calculates if it is a BRK or not (which trashes A)
; Then it sets up the stack like an interrupt and calls 0x3fe
interrupt_handler:
pha ; save A ; 3
; tya
; pha
; txa
; pha
; Should we save X and Y too?
; inc $0404 ; debug
bit $C404 ; clear 6522 interrupt by reading T1C-L ; 4
;============
; 7
;=====================
; Update time counter
;=====================
inc FRAME_COUNT ; 5
lda FRAME_COUNT ; 3
cmp #50 ; 3
bne frame_good ; 3/2nt
lda #$0 ; 2
sta FRAME_COUNT ; 3
update_second_ones:
inc $7d0+17 ; 6
inc $bd0+17 ; 6
lda $bd0+17 ; 4
cmp #$ba ; one past '9' ; 2
bne frame_good ; 3/2nt
lda #'0'+$80 ; 2
sta $7d0+17 ; 4
sta $bd0+17 ; 4
update_second_tens:
inc $7d0+16 ; 6
inc $bd0+16 ; 6
lda $bd0+16 ; 4
cmp #$b6 ; 6 (for 60 seconds) ; 2
bne frame_good ; 3/2nt
lda #'0'+$80 ; 2
sta $7d0+16 ; 4
sta $bd0+16 ; 4
update_minutes:
inc $7d0+14 ; 6
inc $bd0+14 ; 6
; we don't handle > 9:59 songs yet
;=============
; 90 worst
frame_good:
ldy MB_FRAME_DIFF ; get chunk offset ; 3
ldx #0 ; set up reg count ; 2
;=============
; 5
mb_write_loop:
lda (INL),y ; load register value ; 5
; if REG==1 and high bit set
; then end of song
bpl mb_not_done ; 3/2nt
cpx #1 ; 2
bne mb_not_done ; 3/2nt
lda #1 ; set done playing ; 2
sta DONE_PLAYING ; 3
jmp done_interrupt ; 3
mb_not_done:
; special case R13. If it is 0xff, then don't update
; otherwise might spuriously reset the envelope settings
cpx #13 ; 2
bne mb_not_13 ; 3/2nt
cmp #$ff ; 2
beq skip_r13 ; 3/2nt
mb_not_13:
sta MB_VALUE ; 3
; always write out all to zero page
; we mostly care about vola/volb/volc so this wastes 11 bytes of RAM
; code is simpler, and save on three cmp/branches per loop
and #$f ; 2
sta REGISTER_DUMP,X ; 4
; INLINE this (could save 72 cycles)
jsr write_ay_both ; assume 3 channel (not six) ; 6
; so write same to both
; left/right
; 53
clc ; point to next interleaved ; 2
lda INH ; page by adding $300 ; 3
adc #CHUNKSIZE ; 2
sta INH ; 3
inx ; point to next register ; 2
cpx #14 ; if 14 we're done ; 2
bmi mb_write_loop ; otherwise, loop ; 3/2nt
skip_r13:
lda MB_CHUNK ; reset input pointer ; 3
clc ; to the beginning ; 2
adc #>CHUNK_BUFFER ; in proper chunk (1 of 3) ; 2
sta INH ; 3
inc MB_FRAME_DIFF ; increment offset ; 5
bne done_interrupt ; if not zero, done ; 3/2nt
wraparound:
inc MB_CHUNK ; go to next chunk ; 5
lda MB_CHUNK ; 3
cmp #CHUNKSIZE ; have we reached end? ; 2
bne chunk_good ; 3/2nt
lda #0 ; if so reset ; 2
sta MB_CHUNK ; 3
; can't tail call as need to restore stack and rti
jsr next_subsong ; and decompress next ; 6
chunk_good:
done_interrupt:
pla ; restore a ; 4
rti ; return from interrupt ; 6
;=================
; load a new song
;=================
new_song:
;=========================
; Init Variables
;=========================
lda #$0
sta MB_CHUNK
sta FRAME_COUNT
sta A_VOLUME
sta B_VOLUME
sta C_VOLUME
;===========================
; Print loading message
;===========================
jsr clear_bottoms ; clear bottom of page 0/1
lda #0 ; print LOADING message
sta CH
lda #21
sta CV
lda #<loading_message
sta OUTL
lda #>loading_message
sta OUTH
jsr print_both_pages
;===========================
; Load in KRW file
;===========================
lda #<krw_file ; point to filename
sta INL
lda #>krw_file
sta INH
jsr read_file ; read KRW file from disk
;=========================
; Print Info
;=========================
jsr clear_bottoms ; clear bottom of page 0/1
lda #>LZ4_BUFFER ; point to LZ4 data
sta OUTH
lda #<LZ4_BUFFER
sta OUTL
ldy #3 ; skip KRW magic at front
; print title
lda #20 ; VTAB 20: HTAB from file
jsr print_header_info
; Print Author
lda #21 ; VTAB 21: HTAB from file
jsr print_header_info
; Print clock
lda #23 ; VTAB 23: HTAB from file
jsr print_header_info
; 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
; Fall through to next_subsong
;=================
; next sub-song
;=================
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
;===================
; print header info
;===================
; shortcut to print header info
; a = VTAB
print_header_info:
sta CV
iny ; adjust pointer
tya
ldy #0
clc
adc OUTL
sta OUTL
lda OUTH
adc #$0
sta OUTH
lda (OUTL),Y ; get HTAB value
sta CH
inc OUTL ; increment 16-bits
bne bloop22
inc OUTH
bloop22:
jmp print_both_pages ; print, tail call
;==========
; filenames
;==========
krw_file:
.asciiz "INTRO2.KRW"
.asciiz "CRMOROS.KRW"
.asciiz "CHRISTMAS.KRW"
.asciiz "CAMOUFLAGE.KRW"
.asciiz "FIGHTING.KRW"
.asciiz "UNIVERSE.KRW"
.asciiz "TECHNO.KRW"
;=========
;routines
;=========
.include "../asm_routines/gr_offsets.s"
.include "../asm_routines/text_print.s"
.include "../asm_routines/mockingboard_a.s"
.include "../asm_routines/gr_fast_clear.s"
.include "../asm_routines/pageflip.s"
.include "../asm_routines/gr_unrle.s"
.include "../asm_routines/gr_setpage.s"
.include "../asm_routines/dos33_routines.s"
.include "../asm_routines/gr_hlin.s"
.include "../asm_routines/lz4_decode.s"
.include "rasterbars.s"
.include "volume_bars.s"
;=========
; strings
;=========
mocking_message: .asciiz "LOOKING FOR MOCKINGBOARD IN SLOT #4"
not_message: .byte "NOT "
found_message: .asciiz "FOUND"
done_message: .asciiz "DONE PLAYING"
loading_message: .asciiz "LOADING..."
;============
; graphics
;============
.include "chip_title.inc"
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