oivindt@bio.uio.no (Oivind Toien) (05/06/91)
I need a high resolution timer function (at least 100Hz) that works under win 3.0 to trigger an A/D conversion routine. The resolution of the timer function in windows is usually to low (55 ms) to be used for timing an A/D conversion routine. In addition, the priority of timer messages are quite low, so that samples could be lost because of mouse events. It seems that the only way to go is to use an interrupt routine (although the only thing I found in the Petzold book about this is that you should stay with the timer function :-( ). I have two interrupt routines that runs fine under DOS (Turbo-pascal). They both use the Setintvect function to attach Int $1C (the user timer interrupt) to an interrupt routine. When running the same routine under TPW the debugger shows that the address is set correctly to the interrupt routine. But the routine does not seem to be activated. Has anyone has got this to work in either C or TPW? (If interest i can mail the source that works under dos). If someone have some example code they would be willing to share it would be highly appreciated too. -- Oivind Toien <oivindt@ulrik.uio.no> Div. of General Physiology, Dept. of Biology, Univ. of Oslo P.O. Box 1051, N-0316 Oslo 3, NORWAY Phone+47-2-454732 Fax+47-2-454726
Thomas_Hornschuh@p1.f36.n245.z2.fidonet.org (Thomas Hornschuh) (05/09/91)
OT> I have two interrupt routines that runs fine under DOS (Turbo-pascal).
OT> They both use the Setintvect function to attach Int $1C (the user
OT> timer interrupt) to an interrupt routine.
OT>
OT> When running the same routine under TPW the debugger shows that the
OT> address is set correctly to the interrupt routine. But the routine does
OT> not seem to be activated. Has anyone has got this to work in either C
OT> or TPW? (If interest i can mail the source that works under dos).
OT>
You can use the timer interrupt in windows. But you must install a protected
mode interrupt handle with the help of the DPMI (DOS Protected Mode Interface).
DPMI is invoked via INT 31H.
You must use the functions
Name IN OUT
Get Protected Mode Int Vect. AX=0204H,BL=Int Number. CX:DX =
Selector:Offset of
handler
Set " " " " AX=0205H,BL=Int. Number
CX:DX= Selector:Offset
of new handler Carry flag = TRUE
if error
Using this functions is equal to the DOS SetInt/GetInt functions.
Don't forget to chain with a JMP FAR to the old handler at the end of your
new handler.
An alternative is, use your old code as a DOS TSR, load it before windows and
use the DPMI functions to pass control and data between your windows app and
the TSR. But this is more complicated and only usefull if your old code can't
run in protected mode.
The full DPMI specification can ordered from Intel, Santa Clara.
+-----------+ Thomas Hornschuh
| | SoftStream Development
| * | Obermarkstr. 72, D-4600 Dortmund 30, FRG
| * * | Tel ++49-231-48 64 60 Fax ++49-231-48 85 98
| * | FidoNet 2:245/36.1
+-----------+ UseNet: Thomas_Hornschuh%p1.f36.n245.z2@hippo.dfv.rwth-aachen.de