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Commodore 1571 firmware
Utility Routines

        .page  
        .subttl 'lccutil1.src'

;  * utility routines

jerrr   ldy  jobn       ; return  job code
        sta  jobs,y      

        lda  gcrflg     ; test if buffer left gcr
        beq  1$		; no

        jsr  jwtobin    ; convert back to binary

1$      jsr  trnoff     ; start timeout on drive

        ldx  savsp       
        txs     	; reset stack pointer

        jmp  jtop       ; back to the top

;   motor and stepper control
;   irq into controller every 8ms

jend              
        lda  t1hl2	; set irq timer
	sta  t1hc2

	lda  dskcnt
        and  #$10	; wpsw 
        cmp  lwpt       ; same as last
        sta  lwpt       ; update 
        bne  1$

        lda  mtrcnt     ; anything to do?
        bne  7$		; dec & finish up

        beq  2$		; nothing to do

1$	lda  #$ff        
        sta  mtrcnt     ; 255*8ms motor on time
        jsr  moton       

;<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

	jsr  ptch72	; *** rom ds 86 ***
	nop
;       lda  #1          
;       sta  wpsw        

;<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

        bne  2$		; bra

7$      dec  mtrcnt     ; dec & return
        bne  2$
        lda  drvst       
        cmp  #$00       ; motor off & no active drive ?
        bne  2$		; br, do not turn it off something is going on

        jsr  motoff      

2$      lda  phase	; test for phase offset
        beq  5$

        cmp  #2          
        bne  3$

        lda  #0          
        sta  phase
        beq  5$		; bra

3$	sta  steps       
        lda  #2          
        sta  phase
        jmp  6$

5$	ldx  cdrive     ;  work on active drive only
        bmi  8$		;  no active drive

        lda  drvst      ;  test if motor on
        tay      
        cmp  #$20       ;  test if anything to do
        bne  9$		;  something here

8$	jmp  10$	;  motor just running

9$	dec  acltim     ;  dec timer
        bne  11$
	
        tya     	;  test if acel
        bpl  12$


        and  #$7f       ;  over, clear acel bit
        sta  drvst       

12$	and  #$10       ;  test if time out state
        beq  11$

	dec  acltim2	;  decrement second timer
	bne  11$	

	jsr  motoff      

        lda  #$ff       ;  no active drive now
        sta  cdrive      

        lda  #0         ;  drive inactive
        sta  drvst      ;  clear on bit and timout
        beq  8$	

11$	tya     	;  test if step needed
        and  #$40        
        bne  13$	;  stepping

        jmp  10$

13$	lda  nxtst      ; step or settle
        bne  18$	; go set

	lda  steps       
        beq  17$

6$      lda  steps       
        bpl  14$

	tya
	pha		; save regs .y
	ldy  #99	; wait for trk_00
15$	lda  pota1	; check for trk_00
	ror  a		; rotate into carry
	php		; save it
	lda  pota1	; debounce it
        ror  a          ; => carry
        ror  a          ; => bit 7
	plp		; restore carry
	and  #$80	; sclear sign bit
	bcc  21$	

	bpl  16$	; carry set(off) & sign clear(on) exit

	bmi  20$	; bra

21$	bmi  16$	; carry clear(on) & sign set(off) exit
 
20$	dey 
	bne  15$	; wait a while 

	bcs  16$	; br, not track 00 ?

	lda  adrsed	; enabdisable track 00 sense
	bne  16$	; br, nope...

	lda  dskcnt	; phase 0
	and  #3
	bne  16$

	pla
	tay		; restore .y

	lda  #0
	sta  steps	; nomore steps
	jmp  10$

16$	pla
	tay		; restore .y

	inc  steps      ; keep stepping
        lda  dskcnt
        sec      
        sbc  #1        	; -1 to step out
        jmp  19$

17$	lda  #2         ;  settle time
        sta  acltim      
        sta  nxtst      ; show set status
        jmp  10$

18$	dec  acltim      
        bne  10$

        lda  drvst       
        and  #$ff-$40    
        sta  drvst       

        lda  #00         
        sta  nxtst       
        jmp  10$

14$	dec  steps       
        lda  dskcnt
        clc      
        adc  #01         

19$	and  #3          
        sta  tmp         
        lda  dskcnt
;<><><><><><><><><><><><><><><><><><><><><><><><><><><>
;       and  #$ff-$03   ; mask out old
;       ora  tmp         
;	sta  dskcnt
	jmp  ptch0a	; *** rom ds 7/86 ***, finish up
	nop		; fill

10$	jmp  ptch0b	; *** rom ds 7/86 ***, disable SO

;<><><><><><><><><><><><><><><><><><><><><><><><><><><>

        rts


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This page has been created by Sami Rautiainen.
Read the small print. Last updated March 24, 1998.