Multi-Thread question

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:

#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

Good Luck!!!!

------------------
[email protected]



[This message has been edited by Wyman A Belts (edited July 05, 2000).]

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.

------------------
Ron

[Lance Edmonds]

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.

------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Scott Turchin]

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


------------------
Scott
mailto:[email protected][email protected]</A>
MCSE, MCP+Internet