mstp.c

Bacnet protocol stack for linux

                    MSTP_Create_And_Send_Frame(mstp_port, FRAME_TYPE_TOKEN,
                        mstp_port->Next_Station, mstp_port->This_Station, NULL,
                        0);
                    mstp_port->RetryCount = 0;
                    mstp_port->TokenCount = 1;  /* changed in Errata SSPC-135-2004 */
                    mstp_port->EventCount = 0;
                    mstp_port->master_state = MSTP_MASTER_STATE_PASS_TOKEN;
                }
            } else {
                /* SendMaintenancePFM */
                mstp_port->Poll_Station = next_poll_station;
                MSTP_Create_And_Send_Frame(mstp_port,
                    FRAME_TYPE_POLL_FOR_MASTER, mstp_port->Poll_Station,
                    mstp_port->This_Station, NULL, 0);
                mstp_port->RetryCount = 0;
                mstp_port->master_state = MSTP_MASTER_STATE_POLL_FOR_MASTER;
            }
            break;
            /* The PASS_TOKEN state listens for a successor to begin using */
            /* the token that this node has just attempted to pass. */
        case MSTP_MASTER_STATE_PASS_TOKEN:
            if (mstp_port->SilenceTimer < Tusage_timeout) {
                if (mstp_port->EventCount > Nmin_octets) {
                    /* SawTokenUser */
                    /* Assume that a frame has been sent by the new token user.  */
                    /* Enter the IDLE state to process the frame. */
                    mstp_port->master_state = MSTP_MASTER_STATE_IDLE;
                    transition_now = true;
                }
            } else {
                if (mstp_port->RetryCount < Nretry_token) {
                    /* RetrySendToken */
                    mstp_port->RetryCount++;
                    /* Transmit a Token frame to NS */
                    MSTP_Create_And_Send_Frame(mstp_port, FRAME_TYPE_TOKEN,
                        mstp_port->Next_Station, mstp_port->This_Station, NULL,
                        0);
                    mstp_port->EventCount = 0;
                    /* re-enter the current state to listen for NS  */
                    /* to begin using the token. */
                } else {
                    /* FindNewSuccessor */
                    /* Assume that NS has failed.  */
                    mstp_port->Poll_Station = next_next_station;
                    /* Transmit a Poll For Master frame to PS. */
                    MSTP_Create_And_Send_Frame(mstp_port,
                        FRAME_TYPE_POLL_FOR_MASTER, mstp_port->Poll_Station,
                        mstp_port->This_Station, NULL, 0);
                    /* no known successor node */
                    mstp_port->Next_Station = mstp_port->This_Station;
                    mstp_port->RetryCount = 0;
                    mstp_port->TokenCount = 0;
                    /* mstp_port->EventCount = 0; removed in Addendum 135-2004d-8 */
                    /* find a new successor to TS */
                    mstp_port->master_state =
                        MSTP_MASTER_STATE_POLL_FOR_MASTER;
                }
            }
            break;
            /* The NO_TOKEN state is entered if mstp_port->SilenceTimer becomes greater  */
            /* than Tno_token, indicating that there has been no network activity */
            /* for that period of time. The timeout is continued to determine  */
            /* whether or not this node may create a token. */
        case MSTP_MASTER_STATE_NO_TOKEN:
            my_timeout = Tno_token + (Tslot * mstp_port->This_Station);
            if (mstp_port->SilenceTimer < my_timeout) {
                if (mstp_port->EventCount > Nmin_octets) {
                    /* SawFrame */
                    /* Some other node exists at a lower address.  */
                    /* Enter the IDLE state to receive and process the incoming frame. */
                    mstp_port->master_state = MSTP_MASTER_STATE_IDLE;
                    transition_now = true;
                }
            } else {
                ns_timeout =
                    Tno_token + (Tslot * (mstp_port->This_Station + 1));
                if (mstp_port->SilenceTimer < ns_timeout) {
                    /* GenerateToken */
                    /* Assume that this node is the lowest numerical address  */
                    /* on the network and is empowered to create a token.  */
                    mstp_port->Poll_Station = next_this_station;
                    /* Transmit a Poll For Master frame to PS. */
                    MSTP_Create_And_Send_Frame(mstp_port,
                        FRAME_TYPE_POLL_FOR_MASTER, mstp_port->Poll_Station,
                        mstp_port->This_Station, NULL, 0);
                    /* indicate that the next station is unknown */
                    mstp_port->Next_Station = mstp_port->This_Station;
                    mstp_port->RetryCount = 0;
                    mstp_port->TokenCount = 0;
                    /* mstp_port->EventCount = 0; removed Addendum 135-2004d-8 */
                    /* enter the POLL_FOR_MASTER state to find a new successor to TS. */
                    mstp_port->master_state =
                        MSTP_MASTER_STATE_POLL_FOR_MASTER;
                }
            }
            break;
            /* In the POLL_FOR_MASTER state, the node listens for a reply to */
            /* a previously sent Poll For Master frame in order to find  */
            /* a successor node. */
        case MSTP_MASTER_STATE_POLL_FOR_MASTER:
            if (mstp_port->ReceivedValidFrame == true) {
                if ((mstp_port->DestinationAddress == mstp_port->This_Station)
                    && (mstp_port->FrameType ==
                        FRAME_TYPE_REPLY_TO_POLL_FOR_MASTER)) {
                    /* ReceivedReplyToPFM */
                    mstp_port->SoleMaster = false;
                    mstp_port->Next_Station = mstp_port->SourceAddress;
                    mstp_port->EventCount = 0;
                    /* Transmit a Token frame to NS */
                    MSTP_Create_And_Send_Frame(mstp_port, FRAME_TYPE_TOKEN,
                        mstp_port->Next_Station, mstp_port->This_Station, NULL,
                        0);
                    mstp_port->Poll_Station = mstp_port->This_Station;
                    mstp_port->TokenCount = 0;
                    mstp_port->RetryCount = 0;
                    mstp_port->master_state = MSTP_MASTER_STATE_PASS_TOKEN;
                } else {
                    /* ReceivedUnexpectedFrame */
                    /* An unexpected frame was received.  */
                    /* This may indicate the presence of multiple tokens. */
                    /* enter the IDLE state to synchronize with the network.  */
                    /* This action drops the token. */
                    mstp_port->master_state = MSTP_MASTER_STATE_IDLE;
                    transition_now = true;
                }
                mstp_port->ReceivedValidFrame = false;
            } else if ((mstp_port->SilenceTimer >= Tusage_timeout) ||
                (mstp_port->ReceivedInvalidFrame == true)) {
                if (mstp_port->SoleMaster == true) {
                    /* SoleMaster */
                    /* There was no valid reply to the periodic poll  */
                    /* by the sole known master for other masters. */
                    mstp_port->FrameCount = 0;
                    /* mstp_port->TokenCount++; removed in 2004 */
                    mstp_port->master_state = MSTP_MASTER_STATE_USE_TOKEN;
                    transition_now = true;
                } else {
                    if (mstp_port->Next_Station != mstp_port->This_Station) {
                        /* DoneWithPFM */
                        /* There was no valid reply to the maintenance  */
                        /* poll for a master at address PS.  */
                        mstp_port->EventCount = 0;
                        /* transmit a Token frame to NS */
                        MSTP_Create_And_Send_Frame(mstp_port, FRAME_TYPE_TOKEN,
                            mstp_port->Next_Station, mstp_port->This_Station,
                            NULL, 0);
                        mstp_port->RetryCount = 0;
                        mstp_port->master_state = MSTP_MASTER_STATE_PASS_TOKEN;
                    } else {
                        if (next_poll_station != mstp_port->This_Station) {
                            /* SendNextPFM */
                            mstp_port->Poll_Station = next_poll_station;
                            /* Transmit a Poll For Master frame to PS. */
                            MSTP_Create_And_Send_Frame(mstp_port,
                                FRAME_TYPE_POLL_FOR_MASTER,
                                mstp_port->Poll_Station,
                                mstp_port->This_Station, NULL, 0);
                            mstp_port->RetryCount = 0;
                            /* Re-enter the current state. */
                        } else {
                            /* DeclareSoleMaster */
                            /* to indicate that this station is the only master */
                            mstp_port->SoleMaster = true;
                            mstp_port->FrameCount = 0;
                            mstp_port->master_state =
                                MSTP_MASTER_STATE_USE_TOKEN;
                            transition_now = true;
                        }
                    }
                }
                mstp_port->ReceivedInvalidFrame = false;
            }
            break;
            /* The ANSWER_DATA_REQUEST state is entered when a  */
            /* BACnet Data Expecting Reply, a Test_Request, or  */
            /* a proprietary frame that expects a reply is received. */
        case MSTP_MASTER_STATE_ANSWER_DATA_REQUEST:
#if 0
            /* FIXME: we always defer the reply to be safe */
            /* FIXME: if we knew the APDU type received, we could
               see if the next message was that same APDU type
               along with the matching src/dest and invoke ID */
            if ((mstp_port->SilenceTimer <= Treply_delay) &&
                mstp_port->TxReady) {
                /* Reply */
                /* If a reply is available from the higher layers  */
                /* within Treply_delay after the reception of the  */
                /* final octet of the requesting frame  */
                /* (the mechanism used to determine this is a local matter), */
                /* then call MSTP_Create_And_Send_Frame to transmit the reply frame  */
                /* and enter the IDLE state to wait for the next frame. */
                if ((mstp_port->FrameType ==
                        FRAME_TYPE_BACNET_DATA_EXPECTING_REPLY)
                    && (mstp_port->TxReady)) {
                    RS485_Send_Frame(mstp_port,
                        (uint8_t *) & mstp_port->TxBuffer[0],
                        mstp_port->TxLength);
                    mstp_port->TxReady = false;
                    mstp_port->master_state = MSTP_MASTER_STATE_IDLE;
                }
            } else
#endif
                /* DeferredReply */
                /* If no reply will be available from the higher layers */
                /* within Treply_delay after the reception of the */
                /* final octet of the requesting frame (the mechanism */
                /* used to determine this is a local matter), */
                /* then an immediate reply is not possible. */
                /* Any reply shall wait until this node receives the token. */
                /* Call MSTP_Create_And_Send_Frame to transmit a Reply Postponed frame, */
                /* and enter the IDLE state. */
            {
                MSTP_Create_And_Send_Frame(mstp_port,
                    FRAME_TYPE_REPLY_POSTPONED, mstp_port->SourceAddress,
                    mstp_port->This_Station, NULL, 0);
                mstp_port->master_state = MSTP_MASTER_STATE_IDLE;
            }
            break;
        default:
            mstp_port->master_state = MSTP_MASTER_STATE_IDLE;
            break;
    }

    return transition_now;
}

/* note: This_Station should be set with the MAC address */
/* note: Nmax_info_frames should be set */
/* note: Nmax_master should be set */
void MSTP_Init(
    volatile struct mstp_port_struct_t *mstp_port)
{
    int i;      /*loop counter */

    if (mstp_port) {
        mstp_port->receive_state = MSTP_RECEIVE_STATE_IDLE;
        mstp_port->master_state = MSTP_MASTER_STATE_INITIALIZE;
        mstp_port->ReceiveError = false;
        mstp_port->DataAvailable = false;
        mstp_port->DataRegister = 0;
        mstp_port->DataCRC = 0;
        mstp_port->DataCRC = 0;
        mstp_port->DataLength = 0;
        mstp_port->DestinationAddress = 0;
        mstp_port->EventCount = 0;
        mstp_port->FrameType = FRAME_TYPE_TOKEN;
        mstp_port->FrameCount = 0;
        mstp_port->HeaderCRC = 0;
        mstp_port->Index = 0;
        mstp_port->Index = 0;
        for (i = 0; i < sizeof(mstp_port->InputBuffer); i++) {
            mstp_port->InputBuffer[i] = 0;
        }
        mstp_port->Next_Station = mstp_port->This_Station;
        mstp_port->Poll_Station = mstp_port->This_Station;
        mstp_port->ReceivedInvalidFrame = false;
        mstp_port->ReceivedValidFrame = false;
        mstp_port->RetryCount = 0;
        mstp_port->SilenceTimer = 0;
/*        mstp_port->ReplyPostponedTimer = 0; */
        mstp_port->SoleMaster = false;
        mstp_port->SourceAddress = 0;
        mstp_port->TokenCount = 0;
#if 0
        /* these are adjustable, so should already be set */
        mstp_port->Nmax_info_frames = DEFAULT_MAX_INFO_FRAMES;
        mstp_port->Nmax_master = DEFAULT_MAX_MASTER;
#endif

        /* An array of octets, used to store PDU octets prior to being transmitted. */
        /* This array is only used for APDU messages */
        for (i = 0; i < sizeof(mstp_port->TxBuffer); i++) {
            mstp_port->TxBuffer[i] = 0;
        }
        mstp_port->TxLength = 0;
        mstp_port->TxReady = false;
        mstp_port->TxFrameType = 0;

    }
}