I'm _trying_ to write some OS/2 routines (using Watcom 10.6) to control 
the COM port..  and thus far I'm not having any luck.  The documention I have
seems to be FAR from user friendly.  I can't even lock the port at a different
rate.  :)

    Here's my code.. 

#define INCL_DOSPROCESS
#define INCL_DOSFILEMGR
#define INCL_DOSDEVICES
#include 

int main(void)
{
    HFILE  FileHandle;
    ULONG Action;
    ULONG  FileSize, SizeInOut = 0L;
    USHORT FileAttribute = 32;
    ULONG baud=115200;
    APIRET  rc;

    rc = DosOpen("COM2", &FileHandle, &Action, 0L, 0,
0x01, 0x0012, 0L);
    rc = DosDevIOCtl(FileHandle, 0x01, 0x43, &baud, 4L, &FileSize, NULL, 0L, 
         &SizeInOut);
    rc = DosClose(FileHandle);
    
    return 0;
}

    Now, my questions being:

A) what INCL_xxxx lines do I need?  
B) Could someone explain to me the "best" way to open a COM port
for reading 
and writing?
C) For DosDevIOCtl, would someone explain, in detail (if at all possible) what
the ParmList is, and how/when to use it.. what the DataArea is, and how/when 
to use it, what the ParmLengthMax, DataLengthMax, DataLengthInOut, and 
ParmLengthInOut are, and how to use them.  
D) I have two .INF files that give two different specifications for the 
DosDevIOCtl.  One needs 6 parameters, I believe, and the other needs 9.  
Unfortunately Watcom complains if I only use 6, so I guess I should use 9.  
The "6 parameter one" would be for OS/2 2.0 (pre-Warp), correct?

    I'm really lost here, in case you hadn't noticed. :)

    Also, just to make sure, a "word" is an "int" or
"short", correct?
    And a "dword" is a "long", correct?
    And a "byte" is a "char", correct?

    So for function 0x43 in DosDevIOCtl for catagory 1, the ParmList is 
supposed to contain a "dword" (long baud=xxxxxx) and a
"byte" (char 
divisor=xxxx)?  IF this is the case, how do you pass both of those as one 
parameter?  Use a structure?

    If above is correct, then ParmLengthMax would be 5 ("dword"
is 4 bytes + 
"byte" which is 1 byte).  What about DataLengthInOut, ParmLengthInOut, and 
DataLengthMax?

    And if a port is "locked", do you have to "unlock"
it before you can 
change the rate, then do you have to "relock" it?

    I appreciate any and all feedback.  What would _really_ help me is some 
source code with comments telling me exactly what does what. :)


    Thanks..



C. Gaefke
cdgaefke{at}sgi.net
[CDRMAIL Author]

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