dcm44s.a51

8051实时操作系统

;*
;*     DESCRIPTION:    If this station is a slave:
;*                       If in auto mode, jump to auto routine.      
;*                       Else if no frame received, then
;*                               assume transmit ack.  set to auto mode
;*                               and wait on event.
;*                            else jump to slave non-auto rcv routine. 
;*                     If this station is a master:
;*                       If no frame received, then this was a xmit-complete
;*                          interrupt.  So set the serial timeout flag
;*                          and wait on the next event.
;*                       else clear the serial timeout flag and counter
;*                          and jump to the master receive frame routine.
;*
;***************************************************************************

serial_interrupt_check:
    clr     si                           ;clear interrupt flag
    jb      s_station_mode,master_int    ;if master, jump

; Process this interrupt as a non-master
;
    jnb     am, slave_non_auto           ;if slave in flex mode, jump
    ajmp    auto_information_frame_check ;else jump to auto frame check routine

slave_non_auto:
    jb      rbe, slave_xmit_ack          ;if no frame received, jump
    ajmp    non_auto_slave_rcv           ;else process received frame

slave_xmit_ack:
; The interrupt was caused by the completed transmission of a frame by the
; slave.  Set to auto mode.
;
    setb    am                           ;set to auto mode
    ajmp    event_detect                 ;go wait on event

master_int:
    jb      rbe, master_xmit_ack         ;if no receive buffer, then deal with
                                         ;transmit-complete interrupt
master_rcv_int:
; A frame was received by the master.  Go investigate the type of frame
; and process accordingly
;
    clr     si                           ;clear any extra interrupt
    clr     s_timeout_set                ;reset the timeout flag
    clr     s_timeout_count              ;zero the timeout count
    ajmp    non_auto_master_rcv          ;go process received frame

master_xmit_ack:
; Since rbe=1, it is assumed here that the interrupt was caused by
; a transmit-complete condition.
;
    setb    s_timeout_set                ;else set timeout for a response
    ajmp    event_detect                 ;go wait on next event

$EJECT
;***************************************************************************
;*
;*     PROCEDURE:      send_serial
;*
;*     PURPOSE:        initiate serial transmission of message
;*
;*     CALLED FROM:    None
;*
;*     ENTERED FROM:   local_gateway_switch
;*                     parallel_gateway_switch
;*
;*     CALLS:          enqueue_message
;*
;*     ENTERS:         serial_order_send (implicit)    (msg_ptr in R0)
;*                     serial_reply_send               (msg_ptr in R0)
;*
;*     INPUTS:         msg_ptr in R0
;*
;*     RETURNS:        None
;*
;*     DESCRIPTION:    Checks message type for order or reply, then
;*                     jumps to appropriate routine to send it.
;*
;***************************************************************************

send_serial:
; If the link is active (in init., poll, or info. mode), enqueue the message 
; and return.  Otherwise, enqueue the message and initiate transmission
;
        %enqueue_message_def(s_queue_ptr)   ;enqueue the message
        mov     a,#active_link_msk          ;in init, poll, or info mode?
        anl     a,s_station_ops             ;
        jnz     ret_vec                     ;if link active, return
        acall   check_receive_buffer        ;check on receive buffer
        jb      s_station_mode,initiate_order_transmission ;if master, jump 

; This station is not a master.  See if the message is an order or a 
; reply.  If an order, change the station into a master.
;
        %set_msg_ptr(message_route_ofs)     ;check msg type
        mov     a, @r1                      ;
        jnb     acc.msg_type_bpos, send_serial_slave_order ;if order, jump

send_serial_slave_reply:
; This public procedure sends a reply message serially from a slave.
; Inputs:  r0 = the address of the message to be sent
;
        setb    s_info_mode                 ;
        %set_msg_ptr(message_length_ofs)    ;r1,a => message.length
        mov     tbs, a                      ;Set new message pointer
        mov     tbl, @r1                    ;Set new message length
        dec     tbl                         ; 
        dec     tbl                         ; 
        setb    tbf                         ;Enable transmit
ret_vec:
        ret                                 ;Return to wherever this
                                            ; started

send_serial_slave_order:
; The slave is requested to send an order.  Set up for being a master and
; transmit the order message.
; Inputs: r0 => order message
;
        setb    s_station_mode              ;set to master mode
        clr     am                          ;clear auto mode
        mov     a, #ofl_msk                 ;a <= offline mask
        mov     nsnr, a                     ;set nsnr to offline
        mov     dptr, #s_station_state      ;initialize station state table
loop1:                                      ;to all entries offline
        movx    @dptr, a                    ;
        djnz    dpl, loop1                  ;

        mov     dptr, #s_station_poll       ;initialize station poll table
        clr     a                           ;to all zero entries
loop2:                                      ;
        movx    @dptr, a                    ;
        djnz    dpl, loop2                  ;
        mov     s_poll_queue_out, a         ;set poll queue ptr to zero
        mov     stad,#0ffh                  ;set station addr. to ff
 ;      sjmp    initiate_order_transmission ;transmit order as master

$EJECT
;***************************************************************************
;*
;*     PROCEDURE:      initiate_order_transmission
;*
;*     PURPOSE:        initiate_order_transmission starts the serial
;*                     transmission of an order message.
;*
;*     ENTERED BY:     send_serial
;*
;*     CALLED BY:      station_swap_check
;*
;*     CALLS:          None
;*
;*     INPUTS:         Message Pointer: r0
;*
;*     RETURNS:        Nothing
;*
;*     DESCRIPTION:    Checks for destination address match to current
;*                     station address (STAD).  If no match, then
;*                     the current NSNR is written to current station's
;*                     state (s_station_state), and the new station's
;*                     state is written to NSNR --- unless, the station
;*                     is currently unsynchronized.  Then the message is
;*                     pushed back into the queue and a DISC is sent to
;*                     initiate the synchronization handshake.
;*                     Otherwise, the transmit pointer and length are
;*                     set up, and an I frame generated with Nr and Ns
;*                     from NSNR.
;*
;***************************************************************************

initiate_order_transmission:
        %set_msg_ptr(message_station_ofs)   ;check the msg's station
        mov     a,@r1                       ;swap stations if needed
        acall   swap_station_states         ;input: a = msg.stad
        jb      ses, ios_station_init       ;if not yet intitialized, then start
        %set_msg_ptr(message_length_ofs)    ;else set up i-frame for xmit
        mov     tbs, r1                     ;
        mov     tbl, @r1                    ;
        dec     tbl                         ;
        dec     tbl                         ;
        mov     a, nsnr                     ;
        mov     s_last_nsnr, a              ;save current nsnr count
        swap    a                           ;build control byte
        orl     a, #i_msk                   ;
        mov     tcb, a                      ;
        setb    s_info_mode                 ;set to info mode
;       sjmp    ios_frame_transmit          ;

ios_frame_transmit:                         ;transmit frame
        mov     sts, #11100000B             ;rts=1, tbf=1, rbe=1
        ret                                 ;and return

ios_station_init:
        setb    s_init_mode                 ;set to initialization mode
        mov     tcb, #disc_msk              ;set to transmit DISC
        sjmp    ios_frame_transmit

END