mirror of
https://github.com/a2-4am/4cade.git
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174 lines
4.2 KiB
Plaintext
174 lines
4.2 KiB
Plaintext
;license:MIT
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;(c) 2019-2020 by Andrew Roughan, qkumba, 4am
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;
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; Mockingboard support functions
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;
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;------------------------------------------------------------------------------
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; GetMockingboardStuff
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; detect Mockingboard card by searching for 6522 timers across all slots 7->1
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; access 6522 timers with deterministic cycle counts
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;
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; based on prior art in Mockingboard Developers Toolkit
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; with optimisation from deater/french touch
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; also takes into account FastChip //e clock difference
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;
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; in: A/Y contains address of callback to call if card was found
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; (this will be called before the speech detection routine, and
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; (zp$81 will contain the slot in form $Cx)
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; /!\ ALL ACCELERATORS MUST BE OFF OR SET TO 1 MHZ
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; out: if card was found, X = #$?n where n is the slot number of the card, otherwise #$00
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; and bit 6 = 0 if Mockingboard Sound I found
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; or bit 6 = 1 if Mockingboard Sound II or "A" found
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; and bit 7 = 1 if Mockingboard Sound/Speech I or "C" found
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; flags clobbered
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; zp $80-$82 clobbered
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; A/Y clobbered
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;------------------------------------------------------------------------------
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GetMockingboardStuff
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+STAY @callback+1
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lda #$00
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sta $80
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sta $82 ; type
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ldx #$C1
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@slotLoop
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stx $81
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ldy #$04 ; 6522 #1 $Cx04
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jsr @timercheck
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beq @foundI
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@nextSlot
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inx
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cpx #$C8
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bne @slotLoop
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ldx #$00 ; not found
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rts
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@foundI ; sound I or better
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jsr @callback
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ldy #$84 ; 6522 #2 $Cx84
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jsr @timercheck
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beq @foundII
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ldy #$0c
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sty @mb_smc3 + 1
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iny
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sty @mb_smc8 + 1
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iny
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sty @mb_smc7 + 1
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sty @mb_smc11 + 1
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+HIDE_NEXT_2_BYTES
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@foundII ;stereo
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ror $82
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lda $81
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sta @mb_smc1 + 2
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sta @mb_smc2 + 2
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sta @mb_smc3 + 2
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sta @mb_smc4 + 2
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sta @mb_smc5 + 2
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sta @mb_smc6 + 2
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sta @mb_smc7 + 2
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sta @mb_smc8 + 2
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sta @mb_smc9 + 2
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sta @mb_smc10 + 2
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sta @mb_smc11 + 2
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sta @mb_smc12 + 2
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sta @mb_smc13 + 2
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; detect speech chip
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sei
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lda #<@mb_irq
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sta $3fe
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sta $fffe
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lda #>@mb_irq
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sta $3ff
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sta $ffff
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lda #0
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@mb_smc1
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sta $c403
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@mb_smc2
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sta $c402
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lda #$0c
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@mb_smc3
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sta $c48c
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lda #$80
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@mb_smc4
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sta $c443
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lda #$c0
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@mb_smc5
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sta $c440
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lda #$70
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@mb_smc6
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sta $c443
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lda #$82
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@mb_smc7
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sta $c48e
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ldx #0
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ldy #0
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sec
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cli
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@wait_irq
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lda $80
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bne @got_irq
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iny
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bne @wait_irq
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inx
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bne @wait_irq
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clc
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@got_irq
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sei
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ror $82
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@onlyI
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lda $81
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and #7
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ora $82
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tax
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lda #<Ignore
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sta $fffe
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lda #>Ignore
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sta $ffff
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rts ; found
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@timercheck
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sec
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lda ($80),y ; read 6522 timer low byte
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sbc ($80),y ; second time
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cmp #5 ; looking for (-)8 cycles between reads
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beq +
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cmp #6 ; FastChip //e clock is different
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+ rts
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@mb_irq
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lda #2
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@mb_smc8
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sta $c48d
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lda #0
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@mb_smc9
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sta $c440
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lda #$70
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@mb_smc10
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sta $c443
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sta $80
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lda #2
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@mb_smc11
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sta $c48e
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lda #$ff
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@mb_smc12
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sta $c403
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lda #7
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@mb_smc13
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sta $c402
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lda $45
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rti
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@callback
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jmp $FDFD ; SMC
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