[ECOS] cyg_flag_timed_wait doesn't seem to work as expected

[Michael W. Ellis]

I'm running an old version of eCos (2.0.98) from eCosCentric and I'm attempting to use cyg_flag_timed_wait to periodically update a display (see code, below).  My event flag variable g_flags is initialized elsewhere before this thread is created.  Other threads access the same event flag but use their own bits within the flag.

My problem is with the timed wait behavior of the event flag.  At startup I see an initial wait of 30 seconds before the first display update occurs, but the update occurs continually after the initial timeout.  The local variable flags always reads 0, indicating timeout has occurred.  My understanding is that calling cyg_flag_timed_wait at the top of the loop restarts the timer, but this does not seem to be the case.  What am I missing here?  Is there something I must do to clear the timeout event?

Variable allocation and initialization:
static cyg_flag_t g_flags;                                              // thread sync event flags
cyg_flag_init(&g_flags);                                                // init thread sync flag


// ogDisplayThread - update display
static void ogDisplayThread(cyg_addrword_t data)
{
    diag_printf("Entering ogDisplayThread...\r\n");

    cyg_flag_setbits(&g_flags, OG_FLAG_DISP_RDY);                       // say this thread is ready

    while (1)
    {
        cyg_flag_value_t flags;

        flags = cyg_flag_timed_wait(&g_flags,                           // timed wait
                OG_FLAG_DISP_EXIT,                                      // wait for EXIT flag or timeout
                CYG_FLAG_WAITMODE_AND,
                3000);                                                  // 30 second timeout

        diag_printf("ogDisplayThread flag = %08X\r\n", flags);

        if (flags & OG_FLAG_DISP_EXIT)                                  // if EXIT event occurred
        {
            diag_printf("Exiting ogDisplayThread\r\n");

            cyg_flag_maskbits(&g_flags,                                 // say this thread is no longer ready
                    OG_FLAG_DISP_RDY|OG_FLAG_DISP_EXIT);

            cyg_thread_exit();                                          // and exit thread
        }
        else if (!flags)                                                // if timeout occurred (normal condition)
        {
            diag_printf("ogDisplayThread sending data\r\n");
            ogp_msg_t *msg;

            // send IP address
            if (NULL == (msg = malloc(sizeof(ogp_msg_t))))             // allocate a message buffer
                diag_printf("ogDisplayThread malloc error\r\n");
            else
            {
                msg->sync = htonl(OGP_SYNC_WORD);                      // build message
                msg->src = LOCAL_CMD_SRC;
                msg->dst = LOCAL_CMD_DST_SET_IPADDR;
                msg->mtype = LOCAL_CMD_MTYPE;
                api_eth_get_ip(msg->data, 16);                         // get IP address string
                msg->len = htons(strlen(msg->data)+1);                 // set length
                ogpPutTxQ(msg);                                        // send message
            }
        }
        else                                                           // should never get here
            diag_printf("ogDisplayThread unexpected event flag\r\n");
    }
}

Debug output (continual after 30 seconds):
ogDisplayThread flag = 00000000
ogDisplayThread sending data
ogDisplayThread flag = 00000000
ogDisplayThread sending data
ogDisplayThread flag = 00000000
ogDisplayThread sending data
ogDisplayThread flag = 00000000
ogDisplayThread sending data
ogDisplayThread flag = 00000000
ogDisplayThread sending data
ogDisplayThread flag = 00000000
ogDisplayThread sending data
ogDisplayThread flag = 00000000
ogDisplayThread sending data


Thanks,
Michael


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