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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
; tya
; pha
; txa
; pha
; Should we save X and Y too?
; inc $0404 ; debug
bit $C404 ; can clear 6522 interrupt by reading T1C-L
;=====================
; Update time counter
;=====================
inc FRAME_COUNT
lda FRAME_COUNT
cmp #50
bne frame_good
lda #$0
sta FRAME_COUNT
update_second_ones:
inc $7d0+17
inc $bd0+17
lda $bd0+17
cmp #$ba ; one past '9'
bne frame_good
lda #'0'+$80
sta $7d0+17
sta $bd0+17
update_second_tens:
inc $7d0+16
inc $bd0+16
lda $bd0+16
cmp #$b6 ; 6
bne frame_good
lda #'0'+$80
sta $7d0+16
sta $bd0+16
update_minutes:
inc $7d0+14
inc $bd0+14
; we don't handle > 9:59 songs yet
frame_good:
ldy MB_FRAME_DIFF
ldx #0
mb_write_loop:
lda (INL),y
cpx #1
bne mb_not_one
cmp #$ff ; if ff, done song
bne mb_not_one
lda #1
sta DONE_PLAYING
jmp done_interrupt
mb_not_one:
cpx #13
bne mb_not_13
cmp #$ff
beq skip_r13
mb_not_13:
sta MB_VALUE
cpx #8
bne mb_not_8
and #$f
sta A_VOLUME
mb_not_8:
cpx #9
bne mb_not_9
and #$f
sta B_VOLUME
mb_not_9:
cpx #10
bne mb_not_10
and #$f
sta C_VOLUME
mb_not_10:
; INLINE?
jsr write_ay_both ; assume 3 channel (not six)
; so write same to both left/write
clc
lda INH
adc #CHUNKSIZE
sta INH
inx
cpx #14
bmi mb_write_loop
skip_r13:
lda MB_CHUNK
clc
adc #>CHUNK_BUFFER
sta INH
inc MB_FRAME_DIFF
bne done_interrupt
wraparound:
inc MB_CHUNK
lda MB_CHUNK
cmp #CHUNKSIZE
bne chunk_good
lda #0
sta MB_CHUNK
jsr next_subsong
chunk_good:
done_interrupt:
pla
; tax
; pla
; tay
; pla
rti
;=================
; 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
sta OUTH
lda #<LZ4_BUFFER
sta OUTL
ldy #4 ; skip KRW at front
; FIXME: optimize
lda #20
sta CV
lda (OUTL),Y
sta CH
lda OUTL
clc
adc #5 ; point past header stuff
sta OUTL
lda OUTH
adc #0
sta OUTH
jsr print_both_pages
iny
tya
ldy #0
clc
adc OUTL
sta OUTL
lda OUTH
adc #$0
sta OUTH
lda #21
sta CV
lda (OUTL),Y
sta CH
inc OUTL
bne bloop2
inc OUTH
bloop2:
jsr print_both_pages
iny
tya
ldy #0
clc
adc OUTL
sta OUTL
lda OUTH
adc #$0
sta OUTH
lda #23
sta CV
lda (OUTL),Y
sta CH
inc OUTL
bne bloop3
inc OUTH
bloop3:
jsr print_both_pages
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
jsr next_subsong
; should tail call
rts
;=================
; 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
rts
;==========
; filenames
;==========
krw_file:
.asciiz "INTRO2.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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