MBBASE

\ STM8EF-MODBUS Base words for server and client

#require UARTISR
#require CRC16

NVM
  VARIABLE mbp 2 ALLOT  \ MODBUS parameter 1 and 2

  \ 1st MODBUS FC parameter
  : mbp1 ( -- n )
    mbp @
  ;

  \ 2nd MODBUS FC parameter
  : mbp2 ( -- n )
    mbp 2+ @
  ;

  \ MODBUS write response (e.g FC05, FC06, FC15, FC16)
  : MBWR  ( -- )
    mbp1 tx+ mbp2 tx+  \ copy 1st and 2nd parameter
  ;

  \ MB loop (xt) from mbp1 to mbp1+mbp2
  : mbloop ( xt -- )
    mbp1 mbp2 OVER + SWAP  DO
      ( xt ) I OVER EXECUTE
    LOOP
    ( xt ) DROP
  ;

  \ MB looped bit read with action xt, build response (FC01, FC02, FC03, FC04)
  : mbread ( xt bpu -- )
    ( xt bpu ) DUP mbp2 * ( bpu bits )
    \ N* as quantity of bits / 8, if the remainder is different of 0 => N=N+1
    ( bits ) 1- 8 / 1+ ( N* ) DUP txc+
    ( bpu N* ) SWAP ( bpu ) 1 = IF
       ( N* ) 1- FOR 0 txc+ NEXT  \ init bytes in response with 0
    ELSE
       ( N* ) DROP  \ not a bitfield, no memory init
    THEN
    ( xt ) mbloop
  ;

  \ execute xt if not 0
  : @?EXEC ( a -- ) @ ?DUP IF
    ( xt ) EXECUTE
    THEN
  ;

  \ calc CRC16 from buffer a0 to a1
  : MBCRC ( a1 a0 -- crc-le )
    -1 ROT ROT ( -1 a1 a0 ) DO
      I C@ CRC16
    LOOP
    ( CRC16 ) EXG ( CRC-LE )
  ;
RAM