.page  
        .subttl 'opnchnl.src'
; opnchnl

; open a read chanl with 2 buffers
; will insert sa in lintab
; and inits all pointers.
; relative ss and ptrs are set.

opnrch  lda  #1         ; get one data buffer
        jsr  getrch      
        jsr  initp      ; clear pointers
        lda  type        
        pha      
        asl  a   
        ora  drvnum      
        sta  filtyp,x   ; set file type
        jsr  strrd      ; read 1st one or two blocks
        ldx  lindx       
        lda  track       
        bne  or10        

        lda  sector      
        sta  lstchr,x   ; set last char ptr
or10             
        pla      
        cmp  #reltyp     
        bne  or30       ; must be sequential stuff

        ldy  sa          
        lda  lintab,y   ; set channel asw
        ora  #$40        
        sta  lintab,y    

        lda  rec         
        sta  rs,x       ; set record size

        jsr  getbuf     ; get ss buffer
        bpl  or20        
        jmp  gberr      ; no buffer
or20             
        ldx  lindx       
        sta  ss,x        
        ldy  trkss      ; set ss track
        sty  track       
        ldy  secss      ; set ss sector
        sty  sector      
        jsr  seth       ; set ss header
        jsr  rdss       ; read it in
        jsr  watjob      
orow             
        ldx  lindx       
        lda  #2          
        sta  nr,x       ; set for nxtrec

        lda  #0          
        jsr  setpnt     ; set first data byte

        jsr  rd40       ; set up 1st record
        jmp  gethdr     ; restore t&s

or30             
        jsr  rdbyt      ; sequential set up
        ldx  lindx       
        sta  chndat,x    
        lda  #rdytlk     
        sta  chnrdy,x    
        rts      

; initialize variables for open chanl
; lstjob,sets active buffer#,lstchr,
; buffer pointers in buftab=2

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

initp   ldx  lindx       
        lda  buf0,x      
        asl  a   
	bmi  1$		; *** rom ds 85 ***

        tay      
        lda  #2          
        sta  buftab,y    

1$      lda  buf1,x      
        ora  #$80        
        sta  buf1,x      
        asl  a   
	bmi  2$		; *** rom ds 85 ***

        tay      
        lda  #2          
        sta  buftab,y    
2$      lda  #0          
        sta  nbkl,x      

	jmp  ptch41	; *** rom ds 85 ***
	nop		; fill

;       sta  nbkh,x      
;       lda  #0          
;       sta  lstchr,x    
;       rts      

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


; open a write chanl with 2 buffers

opnwch  jsr  intts      ; get first track,sector
        lda  #1          
        jsr  getwch     ; get 1 buffers for writing
        jsr  sethdr     ; set up buffer headers
        jsr  initp      ; zropnt
        ldx  lindx       
        lda  type        
        pha      
        asl  a   
        ora  drvnum      
        sta  filtyp,x   ; set filtyp=seq
        pla      
        cmp  #reltyp     
        beq  ow10        
        lda  #rdylst    ;  active listener
        sta  chnrdy,x    
        rts      

ow10             
        ldy  sa          
        lda  lintab,y    
        and  #$3f        
        ora  #$40        
        sta  lintab,y   ; set channel asw

        lda  rec         
        sta  rs,x       ; set record size

        jsr  getbuf     ; get ss buffer
        bpl  ow20        
        jmp  gberr      ; no buffer
ow20             
        ldx  lindx       
        sta  ss,x        
        jsr  clrbuf      

        jsr  nxtts       
        lda  track       
        sta  trkss      ; save ss t&s
        lda  sector      
        sta  secss       

        ldx  lindx       
        lda  ss,x        
        jsr  seth       ; set ss header
        lda  #0          
        jsr  setssp      
        lda  #0         ; set null link
        jsr  putss       
        lda  #ssioff+1  ; set last char
        jsr  putss       
        lda  #0         ; set this ss #
        jsr  putss       
        lda  rec        ; record size
        jsr  putss       
        lda  track       
        jsr  putss       
        lda  sector      
        jsr  putss       
        lda  #ssioff     
        jsr  setssp      
        jsr  gethdr     ; get first t&s
        lda  track       
        jsr  putss       
        lda  sector      
        jsr  putss       

        jsr  wrtss      ; write it out
        jsr  watjob      
        lda  #2          
        jsr  setpnt      

        ldx  lindx      ; set nr for null buffer
        sec      
        lda  #0          
        sbc  rs,x        
        sta  nr,x        

        jsr  nulbuf     ; null records
        jsr  nullnk      
        jsr  wrtout      
        jsr  watjob      
        jsr  mapout      
        jmp  orow        

;*
;*
;***********************
;*
;* putss
;*
;* put byte into side sector
;*
;***********************
;*
;*
putss   pha      
        ldx  lindx       
        lda  ss,x        
        jmp  putb1