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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