bufmath.b09

PROCEDURE bufmath
(* bare outline of buffer math 8/19/21 ricku
(*
DIM raddr,rbase,rend,rmask,roff,rsize,rptr,rmax,segment:INTEGER
DIM int1,int2,int3,int4:INTEGER

(* rbase   - base address of read buffer
(* rmask   - buffer size mask
(* rptr    - raw ptr from Wizzy. AND with mask to get roff
(* roff    - read offset from start of buffer
(* rend    - end of read buffer
(* raddr   - absolute read address
(* rsize   - total bytes to injest
(* segment - bytes to injest (to EOB or after wraparound)


(* At this point you have sent a request to the server 
(* and are waiting for data 

     (* ____________________________________________ start of read page
     LOOP 
       (* FIXME _____ POLLS say IRQs are better!
       REPEAT 
           POKE $FF69,$04 \ POKE $FF6A,$26 \ (* get Sn_RX_RSR recv size
         rsize:=PEEK($FF6B)*256+PEEK($FF6B)
       UNTIL rsize<>0
       segment:=rsize \ rbase:=$6000
         POKE $FF69,$04 \ POKE $FF6A,$1E \ (* Sn_RXBUF_SIZE
         int1:=PEEK($FF6B)*256+PEEK($FF6B)
       rmask:=1024*int1-1
         POKE $FF69,$04 \ POKE $FF6A,$26 \ (* Sn_RX_RSR
       rsize:=PEEK($FF6B)*256+PEEK($FF6B)
         POKE $FF69,$04 \ POKE $FF6A,$28 \ (* Sn_RX_RD
       rptr:=PEEK($FF6B)*256+PEEK($FF6B)
         int1:=INT(rptr/256) \ int2:=rptr-256*int1
         int3:=INT(rmask/256) \ int4:=rmask-256*int3
         int1:=LAND(int1,int3) \ int2:=LAND(int2,int4)
       roff:=int1*256+int2+rbase

       (* _____________________________________________ parse the frame 
       raddr:=rbase+roff
       IF roff+rsize>rend THEN 
         segment:=rmask+1-roff
         (* GOSUB - process segment bytes of data
         raddr:=rbase \ segment:=rsize-rend
         (* GOSUB - process segment bytes of data 
       ELSE 
         segment:=rsize 
         (* GOSUB - process segment bytes of data
       ENDIF       
       (* __________________ end of a frame. increase Sn_RX_RD by rsize
         POKE $FF69,$04 \ POKE $FF6A,$28
       rptr:=PEEK($FF6B)*256+PEEK($FF6B)+rsize
         POKE $FF69,$04 \ POKE $FF6A,$28
         int1:=INT(rptr/256) \ int2:=rptr-256*int1
       POKE $FF6B,int1 \ POKE $FF6B,int2
       
       POKE $FF69,$04 \ POKE $FF6A,$01 \ POKE $FF6B,$40 \ (*Sn_CR to RECV
     ENDLOOP