dos33fsprogs/chiptune_debug/chiptune_player.s

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; VMW Chiptune Player
.include "zp.inc"
;=============================
; Setup
;=============================
; init variables
lda #0
sta DONE_PLAYING
sta MB_CHUNK_OFFSET
jsr mockingboard_detect_slot4 ; call detection routine
;============================
; 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
.ifdef NOIRQ
.else
lda #<interrupt_handler
sta $03fe
lda #>interrupt_handler
sta $03ff
.endif
;============================
; Enable 50Hz clock on 6522
;============================
.ifdef NOIRQ
.else
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
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.ifdef F25HZ
lda #$40
sta $C404 ; write into low-order latch
lda #$9c
sta $C405 ; write into high-order latch,
; load both values into counter
; clear interrupt and start counting
; 9c40 / 1e6 = .040s, 25Hz
.else
lda #$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
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.endif
.endif
;==================
; load first song
;==================
jsr new_song
;============================
; Enable 6502 interrupts
;============================
.ifdef NOIRQ
.else
cli ; clear interrupt mask
.endif
;============================
; Loop forever
;============================
main_loop:
.ifdef NOIRQ
jsr interrupt_handler
lda #85
jsr WAIT ; wait 20ms-xms
.else
.endif
jmp main_loop
;=================
; load a new song
;=================
new_song:
;=========================
; Init Variables
;=========================
lda #$0
sta MB_CHUNK_OFFSET
lda #3
sta CHUNKSIZE
;===========================
; Load in KRW file
;===========================
lda #<UNPACK_BUFFER ; set input pointer
sta INL
lda #>UNPACK_BUFFER
sta INH
; Decompress first chunks
lda #$3
sta CHUNKSIZE
rts
;=========
;routines
;=========
.include "mockingboard_a.s"
.include "interrupt_handler.s"
.align 256
UNPACK_BUFFER:
.incbin "sdemo.raw"