dos33fsprogs/mode7_demo/interrupt_handler.s
2018-03-19 20:48:41 -04:00

292 lines
7.1 KiB
ArmAsm

; This plays KRG files, stripped down ym5 files
; this is a limited format: the envelope values are ignored
; the fields with don't-care values are packed together
; they are played at 25Hz
; FRAME0 = AFINE (r0)
; FRAME1 = BFINE (r2)
; FRAME2 = CFINE (r4)
; FRAME3 = NOISE PERIOD (r6)
; FRAME4 = ENABLE (r7)
; FRAME5 = ACOARSE/BCOARSE (r1/r3)
; FRAME6 = CCOARSE/AAMP (r5/r8)
; FRAME7 = BAMP/CAMP (r9/r10)
;================================
;================================
; 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
CHUNKSIZE EQU 11 ; hardcoded, based on krg file
interrupt_handler:
pha ; save A ; 3
; Should we save X and Y too?
; inc $0404 ; debug (flashes char onscreen)
bit $C404 ; clear 6522 interrupt by reading T1C-L ; 4
lda DONE_PLAYING ; 3
beq mb_play_music ; if song done, don't play music ; 3/2nt
jmp done_interrupt ; 3
;============
; 13
mb_play_music:
;======================================
; Write frames to Mockingboard
;======================================
; actually plays frame loaded at end of
; last interrupt, so 20ms behind?
mb_write_frame:
;==================================
; loop through the 11 registers
; reading the value, then write out
;==================================
ldx #0 ; set up reg count ; 2
mb_write_loop_left:
lda REGISTER_DUMP,X ; load register value ; 4
cmp REGISTER_OLD,X ; compare with old values ; 4
beq mb_no_write_left ; 3/2nt
;=============
; typ 11
; address
stx MOCK_6522_ORA1 ; put address on PA1 ; 4
lda #MOCK_AY_LATCH_ADDR ; latch_address for PB1 ; 2
sta MOCK_6522_ORB1 ; latch_address on PB1 ; 4
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB1 ; 4
; value
lda REGISTER_DUMP,X ; load register value ; 4
sta MOCK_6522_ORA1 ; put value on PA1 ; 4
lda #MOCK_AY_WRITE ; ; 2
sta MOCK_6522_ORB1 ; write on PB1 ; 4
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB1 ; 4
;===========
; 36
mb_no_write_left:
inx ; point to next register ; 2
cpx #11 ; if 11 we're done ; 2
bmi mb_write_loop_left ; otherwise, loop ; 3/2nt
;============
; 7
ldx #0 ; set up reg count ; 2
mb_write_loop_right:
lda REGISTER_DUMP,X ; load register value ; 4
cmp REGISTER_OLD,X ; compare with old values ; 4
beq mb_no_write_right ; 3/2nt
;=============
; typ 11
; address
stx MOCK_6522_ORA2 ; put address on PA2 ; 4
lda #MOCK_AY_LATCH_ADDR ; latch_address for PB1 ; 2
sta MOCK_6522_ORB2 ; latch_address on PB2 ; 4
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB2 ; 4
; value
lda REGISTER_DUMP,X ; load register value ; 4
sta MOCK_6522_ORA2 ; put value on PA2 ; 4
lda #MOCK_AY_WRITE ; ; 2
sta MOCK_6522_ORB2 ; write on PB2 ; 4
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB2 ; 4
;===========
; 36
mb_no_write_right:
inx ; point to next register ; 2
cpx #11 ; if 11 we're done ; 2
bmi mb_write_loop_right ; otherwise, loop ; 3/2nt
;============
; 7
;=====================================
; Copy registers to old
;=====================================
; 11 coming in
ldx #10 ; 2
mb_reg_copy:
lda REGISTER_DUMP,X ; load register value ; 4
sta REGISTER_OLD,X ; compare with old values ; 4
dex ; 2
bpl mb_reg_copy ; 2nt/3
;=============
; 171
;===================================
; Load all 11 registers in advance
;===================================
; note, assuming not cross page boundary, not any slower
; then loading from zero page?
mb_load_values:
ldy MB_CHUNK_OFFSET ; get chunk offset ; 3
; afine
lda (MB_ADDRL),y ; load register value ; 5
sta A_FINE_TONE ; 3
clc ; point to next interleaved ; 2
lda MB_ADDRH ; page by adding CHUNKSIZE ; 3
adc #CHUNKSIZE ; 3
sta MB_ADDRH ; 3
; bfine
lda (MB_ADDRL),y ; load register value ; 5
sta B_FINE_TONE ; 3
clc ; point to next interleaved ; 2
lda MB_ADDRH ; page by adding CHUNKSIZE ; 3
adc #CHUNKSIZE ; 3
sta MB_ADDRH ; 3
; cfine
lda (MB_ADDRL),y ; load register value ; 5
sta C_FINE_TONE ; 3
clc ; point to next interleaved ; 2
lda MB_ADDRH ; page by adding CHUNKSIZE ; 3
adc #CHUNKSIZE ; 3
sta MB_ADDRH ; 3
; noise
lda (MB_ADDRL),y ; load register value ; 5
sta NOISE ; 3
clc ; point to next interleaved ; 2
lda MB_ADDRH ; page by adding CHUNKSIZE ; 3
adc #CHUNKSIZE ; 3
sta MB_ADDRH ; 3
; enable
lda (MB_ADDRL),y ; load register value ; 5
sta ENABLE ; 3
clc ; point to next interleaved ; 2
lda MB_ADDRH ; page by adding CHUNKSIZE ; 3
adc #CHUNKSIZE ; 3
sta MB_ADDRH ; 3
; acoarse/bcoarse
lda (MB_ADDRL),y ; load register value ; 5
and #$f ; 2
sta B_COARSE_TONE ; 3
lda (MB_ADDRL),y ; load register value ; 5
lsr ; 2
lsr ; 2
lsr ; 2
lsr ; 2
sta A_COARSE_TONE ; 3
clc ; point to next interleaved ; 2
lda MB_ADDRH ; page by adding CHUNKSIZE ; 3
adc #CHUNKSIZE ; 3
sta MB_ADDRH ; 3
; CCOARSE/AAMP
lda (MB_ADDRL),y ; load register value ; 5
and #$f ; 2
sta A_VOLUME ; 3
lda (MB_ADDRL),y ; load register value ; 5
lsr ; 2
lsr ; 2
lsr ; 2
lsr ; 2
sta C_COARSE_TONE ; 3
clc ; point to next interleaved ; 2
lda MB_ADDRH ; page by adding CHUNKSIZE ; 3
adc #CHUNKSIZE ; 3
sta MB_ADDRH ; 3
inx ; point to next register ; 2
; BAMP/CAMP
lda (MB_ADDRL),y ; load register value ; 5
and #$f ; 2
sta C_VOLUME ; 3
lda (MB_ADDRL),y ; load register value ; 5
lsr ; 2
lsr ; 2
lsr ; 2
lsr ; 2
sta B_VOLUME ; 3
;=========================================
; if NOISE is $ff then we are done
lda NOISE ; 3
bpl mb_not_done ; 3/2nt
; lda #1
sta DONE_PLAYING
jsr clear_ay_both
jmp done_interrupt ; 3
;===========
; typ 6
mb_not_done:
;==============================================
; incremement offset. If 0 move to next chunk
;==============================================
increment_offset:
inc MB_CHUNK_OFFSET ; increment offset ; 5
bne increment_done ; if not zero, done ; 3/2nt
inc WHICH_CHUNK
lda WHICH_CHUNK
cmp #CHUNKSIZE
bne increment_done
lda #0
sta WHICH_CHUNK
increment_done:
lda #>music_start
clc
adc WHICH_CHUNK
sta MB_ADDRH
;=================================
; Finally done with this interrupt
;=================================
done_interrupt:
exit_interrupt:
pla ; restore a ; 4
rti ; return from interrupt ; 6
;============
; typical
; ???? cycles
REGISTER_OLD:
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0