Subj : Re: passing an 'int' to a thread
To   : comp.programming.threads
From : Uenal Mutlu
Date : Wed Jun 08 2005 08:50 am

Simply just use the debugger and set some breakpoints and then
inspect the variables of interest to you. You can of course also
step thru the code while the debugger is running.


"Huub" <hdotvdotniekerkathccnetdotnl> wrote
> You were right. The errors were due to a linking problem. And I made a
> another mistake which I corrected. Now something is being passed, but
> it's not the correct value. Could you tell me what is being passed:
> task_ids or t?
>
> New code:
>
>
> #ifdef HAVE_CONFIG_H
> #include <config.h>
> #endif
>
> #include <iostream>
> #include <cstdlib>
> #include <memory>
> #include <pthread.h>
> #include <time.h>
> #include "ftapi/ftapi.h"
>
> using namespace std;
> using namespace ftapi;
>
>    // default interface connection
> string device("");
> ft_if_conn connection = FT_IC_LIB_USB;
> IfOutputs out;
> IfInputs inp;
>
> void *MotorDraad(void *threadid)
> {
>    int *id_ptr, task_id;
>    id_ptr = (int *)threadid;
>    task_id = *id_ptr;
>    cout << "Start MotorDraad" << endl;
>    time_t start;
>    time_t current;
>    time(&start);
>    try
>    {
>      auto_ptr<FtInterface> fti (ftGetIfFromFactory(device,
>   connection));
>    // Initialspeed = task_id
>      FtMotorSpeed mSpeed1(task_id);
>      cout << "Snelheid1 = " << task_id << endl;
>    // Initialspeed = task_id
>      FtMotorSpeed mSpeed2(task_id);
>      cout << "Snelheid2 = " << task_id << endl;
>    // enable all motor outputs
>      out.data[FT_MASTER]= 0xFF;
>    // M1: not moving
>      out.setMotorSpeed(FT_MASTER, FT_M1, mSpeed1);
>    // M2: forward with velocity 4
>      out.setMotorSpeed(FT_MASTER, FT_M2, mSpeed2);
>      while (difftime(current,start) < 5.0)
>      {
>        time(&current);
>        fti->writeAndReadAllData(out, inp);
>      }
>    }
>    // anything went wrong
>    catch (exception &x)
>      {
>        cout << x.what() << endl;
>      }
> }
>
>
> int main(int argc, char *argv[])
> {
>    cout << "Start fase 1" << endl;
>
>    pthread_t threads[1];
>    int *task_ids[1];
>    int rc, t;
>    t = 0;
>    int snelheid = 0;
>
>    cout << "1 Thread gedeclareerd" << endl;
>
>    cout << "fttestextension v0.4" << endl;
>
>    if (1 == argc)
>      {
>        /* leave device name as defined above, since no
> parameters given */
>      }
>    else if (((2 == argc) || (3 == argc)) &&
>    (string("-l")==(argv[1])))
>      {
>        if (3 == argc) device = argv[2];
>        connection = FT_IC_LIB_USB;
>      }
>    else if (((2 == argc) || (3 == argc)) &&
>    (string("-u")==(argv[1])))
>      {
>        if (3 == argc)
> {
>   device = argv[2];
> }
>        else
> {
>   device = "/dev/usb/robointerface0";
> }
>        connection = FT_IC_USB;
>      }
>    else
>      {
>        return EXIT_FAILURE;
>      }
>
>    // now let's go!
>    cout << "opening fischertechnik interface \"" << device << "\""
>         << endl;
>    task_ids[t] = (int *) malloc(sizeof(int));
>    *task_ids[t] = t;
>    while (snelheid != 8)
>      {
>        cin >> snelheid;
>        cout << "Aanmaken thread" << endl;
>        cout << "t = " << t << endl;
>        t = snelheid; // new piece of code
>        rc = pthread_create(&threads[t], NULL, MotorDraad,
>   (void *)task_ids[t]);
> //what is passed: task_ids or t?
>      }
>    pthread_exit(NULL);
>    return EXIT_SUCCESS;
> }
>
> // EOF
>
> Thank you for helping out.

.