sorgom / dstw

Digital Interlockig (DSTW) Implementation, C++, SIL4, CppUTest

DSTW

the project

An implementation of an interlocking control logic (ICL) which represents the states of field elements like signals or track switches and communicates with control panels (GUIs) and the real field elements.

It consists of the following components:

• TSW: track switches
• SIG: signals
• LCR: level crossings
• SEG: track segments
• SYS: commonly used system
• COM: TCP communication to field and GUI

goals

The project does not intend an implementation that would work in a real digital interlocking (DSTW).

The aim is to

• apply and demonstrate techniques to meet security integrity level 4 (SIL4).
• show a completely different approach than the model driven one I happened to experience.
• use as much modern C++ as possible
• gain AI usage experience

components interaction overview

topics

• SIL4
• AI usage
• testing
• transition tables
• code coverage
• how to build
• current lines of code

dstw's Issues

I_TCP: select return should be an enum

    //  read select a socket
    //  -1 on error
    //   0 if no socket is ready
    //   1 if socket is ready
    virtual INT32 select(INT32 socket) const = 0;

make the byte order header only

involved:

• application\components\BAS\src\HN.cpp
• application\components\BAS\HN.h

current cpp:

#ifdef _WIN32
#include <winsock2.h>
#else
#include <arpa/inet.h>
#endif

UINT32 HN::toN(const UINT32 val)
{
    return htonl(val);
}

UINT32 HN::toH(const UINT32 val)
{
    return ntohl(val);
}

UINT16 HN::toN(const UINT16 val)
{
    return htons(val);
}

UINT16 HN::toH(const UINT16 val)
{
    return ntohs(val);
}

• move this to header and make it inline
• resolve VS problems

check integer sizes on linux (WSL)

looks like an INT32 has 8 bytes

the great refactoring

changes

• I_Provider
• I_Hub
• one telegram type, 2 derived ones:
  • teleFld
  • teleGui
• containers:
  • Index non const
  • reserve without return
• enums
  • one enum for all states
• testing
  • one mock for all Hubs
  • one mock for all Providers
• adapt genCode

TestStepper segmentation fault when ENDSTEPS() without previous SUBSTEPS()

establish TCP communication

Com

The COM interface has to communicate via TCP:

• 1 GUI connection
• 1 FLD connection
• 1 CTRL connection

new interface methods

• shutdown
• run with ComSetup data
  • call Dispatcher recall field

new data

• ComSetup
• ComTele for shutdown

other modules

Dispatcher

• send re-call telegrams to field when
  • field reconnects
• send UNDEF telegrams to GUI when
  • field disconnects

  TODO ...

introduce packBegin packEnd headers

#define CPPUTEST_MEM_LEAK_DETECTION_DISABLED

in: testing/testenv/testlib/CppUTest.h

check if needed

capacity check for static arrays

improve project readme

DSTW/README.md

Line 3 in da2a200

## state of implementation

recommendation:

• get rid of the releases stuff
• write a project description
  • motivation
  • why this is better and SIL4
  • techniques applied
  • and so on

bug: wrong code in TCP_Client

this code is wrong:

    bool TCP_Client::recv(PTR data, INT32 size) const
    {
        fd_set readfds;
        FD_ZERO(&readfds);
        FD_SET(mSocket, &readfds);
        timeval timeout{0, 50000};
        bool ok = false;
        if (
            (::select(mSocket + 1, &readfds, nullptr, nullptr, &timeout) >= 0) and
            (FD_ISSET(mSocket, &readfds))
        )
        {
            ok = ::recv(mSocket, static_cast<char*>(data), size, 0) == size;
        }
        return ok;
    }

after successful select the client

• must read as much as possible
• call on Receive with ComTele with each sizeof(ComTele)

bug #57

more documetation required

• continue SIL4
• howto build VS

CPPUTEST_MEM_LEAK_DETECTION_DISABLED

make clear why this is a good option

Re-design Static Array

The StaticArray class has too many options.

Create dedicated classes:

InterfaceArray

• not sortable
• main class virtual
• add of derived class
• non const access

FixedDataArray

• not sortable
• const access only
• only main class

Index

• refers FixedDataArray
• is sortable
• virtual is greater