dos33fsprogs/pt3_player/interrupt_handler.s
2019-05-07 15:11:52 -04:00

249 lines
5.1 KiB
ArmAsm

;================================
;================================
; mockingboard 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
TIME_OFFSET EQU 13
interrupt_handler:
; pha ; save A ; 3
; A is saved in $45 by firmware
txa
pha ; save X
tya
pha ; save Y
inc $0404 ; debug (flashes char onscreen)
bit $C404 ; clear 6522 interrupt by reading T1C-L ; 4
; jmp exit_interrupt
lda DONE_PLAYING ; 3
beq pt3_play_music ; if song done, don't play music ; 3/2nt
jmp check_keyboard ; 3
;============
; 13
pt3_play_music:
; for(i=0;i < pt3.music_len;i++) {
; pt3_set_pattern(i,&pt3);
; for(j=0;j<64;j++) {
; if (pt3_decode_line(&pt3)) break;
; for(f=0;f<pt3.speed;f++) {
jsr pt3_make_frame
;======================================
; Write frames to Mockingboard
;======================================
; actually plays frame loaded at end of
; last interrupt, so 20ms behind?
mb_write_frame:
ldx #0 ; set up reg count ; 2
;============
; 2
;==================================
; loop through the 14 registers
; reading the value, then write out
;==================================
mb_write_loop:
lda REGISTER_DUMP,X ; load register value ; 4
; special case R13. If it is 0xff, then don't update
; otherwise might spuriously reset the envelope settings
cpx #13 ; 2
bne mb_not_13 ; 3/2nt
cmp #$ff ; 2
beq mb_skip_13 ; 3/2nt
;============
; typ 5
mb_not_13:
; address
stx MOCK_6522_ORA1 ; put address on PA1 ; 4
stx MOCK_6522_ORA2 ; put address on PA2 ; 4
lda #MOCK_AY_LATCH_ADDR ; latch_address for PB1 ; 2
sta MOCK_6522_ORB1 ; latch_address on PB1 ; 4
sta MOCK_6522_ORB2 ; latch_address on PB2 ; 4
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB1 ; 4
sta MOCK_6522_ORB2 ; 4
; value
lda REGISTER_DUMP,X ; load register value ; 4
sta MOCK_6522_ORA1 ; put value on PA1 ; 4
sta MOCK_6522_ORA2 ; put value on PA2 ; 4
lda #MOCK_AY_WRITE ; ; 2
sta MOCK_6522_ORB1 ; write on PB1 ; 4
sta MOCK_6522_ORB2 ; write on PB2 ; 4
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB1 ; 4
sta MOCK_6522_ORB2 ; 4
;===========
; 62
mb_no_write:
inx ; point to next register ; 2
cpx #14 ; if 14 we're done ; 2
bmi mb_write_loop ; otherwise, loop ; 3/2nt
;============
; 7
mb_skip_13:
;=================================
; Finally done with this interrupt
;=================================
done_interrupt:
;=====================
; Update time counter
;=====================
update_time:
inc FRAME_COUNT ; 5
lda FRAME_COUNT ; 3
cmp #50 ; 3
bne done_time ; 3/2nt
lda #$0 ; 2
sta FRAME_COUNT ; 3
update_second_ones:
inc $7d0+TIME_OFFSET+3 ; 6
inc $bd0+TIME_OFFSET+3 ; 6
lda $bd0+TIME_OFFSET+3 ; 4
cmp #$ba ; one past '9' ; 2
bne done_time ; 3/2nt
lda #'0'+$80 ; 2
sta $7d0+TIME_OFFSET+3 ; 4
sta $bd0+TIME_OFFSET+3 ; 4
update_second_tens:
inc $7d0+TIME_OFFSET+2 ; 6
inc $bd0+TIME_OFFSET+2 ; 6
lda $bd0+TIME_OFFSET+2 ; 4
cmp #$b6 ; 6 (for 60 seconds) ; 2
bne done_time ; 3/2nt
lda #'0'+$80 ; 2
sta $7d0+TIME_OFFSET+2 ; 4
sta $bd0+TIME_OFFSET+2 ; 4
update_minutes:
inc $7d0+TIME_OFFSET ; 6
inc $bd0+TIME_OFFSET ; 6
; we don't handle > 9:59 songs yet
done_time:
;=============
; 90 worst
;=================================
; Moved visualization here as a hack
;=================================
;============================
; Visualization
;============================
; jsr clear_top
; lda RASTERBARS_ON
; beq skip_rasters
; jsr draw_rasters
;skip_rasters:
; jsr volume_bars
; jsr page_flip
check_keyboard:
jsr get_key
lda LASTKEY
beq exit_interrupt
cmp #(' '+$80)
bne key_R
key_space:
lda #$80
eor DONE_PLAYING
jmp quiet_exit
key_R:
cmp #'R'
bne key_left
lda #$ff
eor RASTERBARS_ON
sta RASTERBARS_ON
jmp done_key
key_left:
cmp #'A'
bne key_right
lda #$40
bne quiet_exit
key_right:
cmp #'D'
bne done_key
lda #$20
bne quiet_exit
done_key:
jmp exit_interrupt
quiet_exit:
sta DONE_PLAYING
jsr clear_ay_both
;=====================================
; clear register area
;=====================================
ldx #13 ; 2
lda #0 ; 2
mb_clear_reg:
sta REGISTER_DUMP,X ; clear register value ; 4
dex ; 2
bpl mb_clear_reg ; 2nt/3
exit_interrupt:
; pla ; restore a ; 4
pla
tay ; restore Y
pla
tax ; restore X
lda $45 ; restore A
rti ; return from interrupt ; 6
;============
; typical
; ???? cycles