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If I want to build a ring detector for COMM work, and I want to spawn a simple thread that just sits there and listens for a RING, how would I do a Dialog Doevents so the thread didn't use any resources if nothing was happening on the line.
Scott Turchin
MCSE, MCP+I http://www.tngbbs.com
---------------------- True Karate-do is this: that in daily life, one's mind and body be trained and developed in a spirit of humility; and that in critical times, one be devoted utterly to the cause of justice. -Gichin Funakoshi
The thread would just have to loop around until COMM(#hComm, RXQUE) was non-zero. Because this thread would not contain any GUI related code, DIALOG DOEVENTS would not be necessary unless another thread was causing starvation of the monitoring thread. Therefore, the thread would use no GDI resources and with the appropriate SLEEP time-slice releasing, would use a very low level of CPU time.
One note: DIALOG DOEVENTS is a PB/DLL statement, so you need to write your own message loop for PB/CC, but one important fact is that that a PB/CC app should never do this unless it really does create a GUI window (which is allowed to be hidden). Without a GUI window, you will run into GPF problems on some versions of Windows.
Since you are a registered PB/DLL 6.0 customer Scott, check out the COMM.BAS example in the SAMPLES folder - the COMM 'Receive' thread should be easily modified to poll for receive buffer activity, which can them be examined for the "RING" + CHR$(13,10) stream. I'm not at my DEV PC to check, but I seem to remember using a thread in the PB/CC example too.
Check out the COMMTIMEOUTS and ReadFile APIs. ReadFile and CTO
can do your "sleeps" while waiting for a specified number of
characters to be received. If you are writing for NT you can use
the SetCommMask and WaitCommEvent APIs to wait for a ring.
Hi Scott,
I think you posted something about this before, and I've done
some research since then. I've been successfully using a
variation of the following code for awhile now and it works fine.
Tom Hanlin said something about Ring detection being inconsistent,
but it's worked fine for me on a lowball Win LT modem on Win2000
and Windows Millenium. Anyway, here goes:
Code:
#Compile Exe "C:\RINGTEST.EXE"
#Include "Win32api.inc"
Function CommWait(ByVal PortHandle As Long) As Long
Dim EventMaskIn As Long 'Bit Map Of Event that occured
'Tell Win32 What To Wait For:
Call SetCommMask(PortHandle, %EV_RING)
'Now Wait:
Call WaitCommEvent(PortHandle, EventMaskIn, ByVal 0&)
Print "Ring Detected"
End Function
Function WinMain(ByVal hCurInstance As Long, _
ByVal hPrevInstance As Long, _
lpszCmdLine As Asciiz Ptr, _
ByVal nCmdShow As Long) Export As Long
Dim hComm As Long
Dim hCommPB As Long
Dim hThread As Long
Dim RingDetected As Long
'Open a PB Comm Port:
Comm Open "COM3" As #hCommPB
'Get The Win32 Handle:
hComm = FileAttr(hCommPB, 2)
'Set The Comm Port Params:
Comm Set #hCommPB, Baud = 57600
Comm Set #hCommPB, Byte = 8
Comm Set #hCommPB, Parity = %False
Comm Set #hCommPB, Stop = 0
Comm Set #hCommPB, TxBuffer = 2048
Comm Set #hCommPB, RxBuffer = 4096
Thread Create CommWait(hComm) To hThread
Do
Sleep 500
Thread Status hThread To RingDetected
Loop Until RingDetected = 0 'Thread's Dead
Print "Press Any Key To End"
WaitKey$
Comm Close #hCommPB
End Function
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