88 lines
1.9 KiB
ArmAsm
88 lines
1.9 KiB
ArmAsm
|
|
mockingboard_detect:
|
|
|
|
;================================
|
|
; Mockingboard detect
|
|
;================================
|
|
|
|
jsr mockingboard_detect_slot4 ; call detection routine
|
|
stx MB_DETECTED
|
|
|
|
;================================
|
|
; Mockingboard start
|
|
;================================
|
|
|
|
mockingboard_setup:
|
|
sei ; disable interrupts just in case
|
|
|
|
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
|
|
; 9c40 / 1e6 = .040s, 25Hz
|
|
|
|
;============================
|
|
; Start Playing
|
|
;============================
|
|
main_loop:
|
|
lda MB_DETECTED
|
|
beq mockingboard_setup_done
|
|
|
|
lda #0
|
|
sta DONE_PLAYING
|
|
sta WHICH_CHUNK
|
|
sta MB_CHUNK_OFFSET
|
|
sta MB_ADDR_L ; we are aligned, so should be 0
|
|
|
|
lda #>music_start
|
|
sta MB_ADDR_H
|
|
|
|
;=====================================
|
|
; clear register area
|
|
;=====================================
|
|
ldx #13 ; 2
|
|
lda #0 ; 2
|
|
mb_setup_clear_reg:
|
|
sta REGISTER_DUMP,X ; clear register value ; 4
|
|
sta REGISTER_OLD,X ; clear old values ; 4
|
|
dex ; 2
|
|
bpl mb_setup_clear_reg ; 2nt/3
|
|
|
|
cli ; start interrupts
|
|
|
|
mockingboard_setup_done:
|
|
|
|
rts
|