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**Mel Bishop** · 26 Jul 2004, 09:59 PM

MTIMER is accurate within the specs you provided, but: That
function is useful for checking how long something takes.

Using MTIMER to set up a delay is gonna be a tough nut to crack.
Have you checked out the "DELAY" function? That might be more
useful.

------------------

**Tim Horton** · 26 Jul 2004, 10:38 PM

I was thinking that the execution of the MTIMER statement (to zero the timer) would take a negligable amount of time. I would then perform some dummy instruction (like perform a dozen cosine calculations) and then perform an MTIMER function (ie d = MTIMER).

I would then add d to totald and if totald reaches some value I'd exit the routine. Otherwise zero the timer, perform the cosine calc's, etc.

I find that the execution time of the MTIMER statement is large. In tests running in DOS mode (not under Windows) I find that it takes 55 seconds to perform 500 MTIMER statement-function commands. That's 110 milliseconds of overhead. No difference if I run the test routine in the PowerBasic interpreter or compiled from the DOS prompt.

The DELAY function won't work because it's resolution is 54 milliseconds (I wanted a time-delay from zero to 10 milliseconds max, with a resolution of 100 microseconds or better).

It looks like I will build a time-delay routine by simply performing a variable amount of cosine calculations.

**Peter Lameijn** · 27 Jul 2004, 05:53 AM

This old function works fine under DOS. Don't know if it's supported under Windows...

Code:

'====================================================================
' uS_Wait: Waits for [uS] time before returning.
' Uses the special DOS timer function 0x15, ax= 0x8300/01
'--------------------------------------------------------------------
SUB uS_Timer(uS AS Long) PUBLIC
  DIM uSec AS LOCAL LONG
  uSec = uS
  REG %AX, &H8301
  CALL INTERRUPT &H15
 
  REG %AX, &H8300
  REG %DX, uSec AND &H0000FFFF
  SHIFT RIGHT uSec, 16
  REG %CX, uSec& AND &H0000FFFF
  uSec = 0
  REG %ES, VARSEG (uSec)
  REG %BX, VARPTR (uSec)
  CALL INTERRUPT &H15
  WHILE ISFALSE uSec : WEND
END SUB

------------------
Regards,
Peter

**Hans Ruegg** · 31 Jul 2004, 11:02 AM

I suppose (correct me if I am mistaken) that MTIMER always waits
until the next system timer tick (the one which occurs about
18 times a second), before it actually begins counting
time.

Regards,

Hans Ruegg

------------------

**Michael Mattias** · 1 Aug 2004, 06:28 AM

A long, long time ago (my first paying contract, in fact)....

I had to put in some fairly small delays to control a piece of measuring equipment...

What I ended up doing was using empty FOR...NEXT loops; but of course this would cause problems on different-speed machines... so I added a user-defined "timer delay" in the INI file which represented "number of empty loops for machine delay."

Since my delay for this equipment was neither 'absolute' time sensitive (that is, exactly "how long" the delay had to be, it only had to be 'enough') nor varied once the program started, this worked fine.

If you do have absolute and/or variable time requirements, you could set a variable to specify "loops per millisecond" or "loops per microsecond" and either let the user 'tune' it or run some routine yourself when the program starts up to calculate this number.

It's a thought.

MCM

**Paul Dixon** · 1 Aug 2004, 04:38 PM

tim,
1) mtimer is only good for one off timings. i think it waits until the 55ms pit timer passes zero and then returns. the mtimer function then just reads the pit registers to see how many clock ticks have passed since the start and that's the value returned.
this method means that, regardless of how fast your code is, if you call mtimer twice or more then the minimum delay between consecutive calls is 55ms.

2) if you're running under windows timings will not be reliable.

3) check out these for
a) a much more accurate delay routine (but you don't really want a delay routine as a delay will not return to allow you to do your calculations while the delay is in progress) http://www.powerbasic.com/support/pb...ad.php?t=22773

b) a proper high resolution timer which is what you really want.. but it'll still only work under dos, not windows. http://www.powerbasic.com/support/pb...ad.php?t=23521

4) you're probably better off using the normal timer once to find how many calculations you can do in 1 second and then using that calculation rate to set the limit on the number of total calculations you do before exiting.

paul.

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**Gustavo Asplanatti** · 5 Aug 2004, 06:32 PM

Hi Tim, This work very well in Windows real mode (DOS 7.02), I don´t
test in protected mode.

Code:

'==============================================================================
' FILE NAME   : HR_TIMER.INC
'==============================================================================
' DESCRIPTION :
' High Resolution time measurement.
' Include File For Using in Real DOS mode.
'
'==============================================================================
' COMPILER VERSION : PB DOS 3.5
' CREATION DATE    : May , 2004
'==============================================================================
' E-MAIL : [email protected]
'==============================================================================
' AUTHOR  : Gustavo D. Asplanatti.
'
' LICENCE/TERMS AND CONDITIONS
'
' This code is free for all PB user     [img]http://www.powerbasic.com/support/forums/wink.gif[/img]
' Use it at your own risk.
'==============================================================================

DECLARE SUB DoSleep(TimeToSleep AS EXT)
DECLARE FUNCTION MyTime(Decimal AS BYTE) AS STRING
DECLARE FUNCTION GetTime() AS EXT
DECLARE FUNCTION GetTickCount() AS EXT

DIM TickFreq AS SHARED EXT

TickFreq = 1193181.7/65536

SUB DoSleep(TimeToSleep AS EXT)
   DIM ATime AS LOCAL EXT
   DIM BTime AS LOCAL EXT
   DIM DeltaAB AS LOCAL EXT
   ATime = GetTime()
   DO
      BTime = GetTime()
      IF BTime >= ATime THEN DeltaAB = BTime - ATime ELSE DeltaAB = (86400 - ATime) + BTime
      IF DeltaAB >= TimeToSleep THEN EXIT LOOP
   LOOP
END SUB

FUNCTION MyTime(Decimal AS BYTE) AS STRING
   DIM CountTime AS LOCAL EXT, resto AS LOCAL EXT
   DIM Hora AS LOCAL STRING, Minu AS LOCAL STRING
   DIM Secu AS LOCAL STRING, Mili AS LOCAL STRING
   FLEXCHR$ = "0"
   Hora = STRING$(2, FLEXCHR$)
   Minu = STRING$(2, FLEXCHR$)
   Secu = STRING$(2, FLEXCHR$)
   Mili = STRING$(Decimal, FLEXCHR$)
   CountTime = GetTime()
   RSET Hora = TRIM$(STR$(CountTime \ 3600))
   Resto = CountTime MOD 3600##
   RSET Minu = TRIM$(STR$(Resto \ 60##))
   Resto = Resto MOD 60##
   RSET Secu = TRIM$(STR$(FIX(Resto)))
   IF Decimal > 0 THEN
      RSET Mili = TRIM$(STR$(FIX(FRAC(Resto)*(VAL("1" & STRING$(Decimal,"0"))))))
      MyTime = Hora & ":" & Minu & ":" & Secu & "." & Mili
   ELSE
      MyTime = Hora & ":" & Minu & ":" & Secu
   END IF
END FUNCTION

FUNCTION GetTime() AS EXT
   DIM AuxTick1 AS EXT, AuxTick2 AS EXT
   AuxTick1 = GetTickCount() : AuxTick2 = AuxTick1
   WHILE AuxTick2<=AuxTick1
      AuxTick2 = GetTickCount()
      IF AuxTick2 > 1573038## THEN EXIT LOOP    ' 1573040 Eq. 24 hs.
   WEND
   GetTime = AuxTick2 / TickFreq
END FUNCTION

FUNCTION GetTickCount() AS EXT
   DIM ClockState AS LOCAL BYTE
   DIM LoByteTickC AS LOCAL WORD, HiByteTickC AS LOCAL WORD
   DIM LoByte40 AS LOCAL BYTE, HiByte40 AS LOCAL BYTE

   ! PUSHF
   ! CLI

   ! MOV AH, &H00                      ; Interroga Tick counter
   ! INT &H1A
   ! MOV HiByteTickC, CX
   ! MOV LoByteTickC, DX

   ! MOV AX,&HE2                       ; Estado del Out de clock 0
   ! MOV DX, &H043
   ! OUT DX, AL
   ! IN  AX, &H040
   ! MOV ClockState, AX

   ! MOV AX,&H0
   ! MOV DX, &H043
   ! OUT DX, AL
   ! IN  AX, &H040
   ! MOV LoByte40, AX
   ! IN  AX, &H040
   ! MOV HiByte40, AX

   ! POPF

   GetTickCount = (LoByteTickC + HiByteTickC * 65536) + _
                  ((65535-(LoByte40 + HiByte40 * 256)) / 2 / 65536) + 0.5 * NOT(BIT(ClockState,7))
END FUNCTION

------------------
Gustavo Asplanatti
[email protected]

**Gustavo Asplanatti** · 5 Aug 2004, 06:36 PM

Test with this test program

Code:

'==============================================================================
' FILE NAME   : TEST_HR.BAS
'==============================================================================
' DESCRIPTION :
' Test High Resolution time measurement.
'
'==============================================================================
' COMPILER VERSION : PB DOS 3.5
' CREATION DATE    : May , 2004
'==============================================================================
' E-MAIL : [email protected]
'==============================================================================
' AUTHOR  : Gustavo D. Asplanatti.
'
' LICENCE/TERMS AND CONDITIONS
'
' This code is free for all PB user     [img]http://www.powerbasic.com/support/forums/wink.gif[/img]
' Use it at your own risk.
'==============================================================================


$ERROR ALL ON
$DIM ALL
$CPU 80386
$FLOAT NPX
$OPTIMIZE SPEED
$INCLUDE "HR_TIMER.INC"

CLS

LOCATE 06,02 : PRINT " HR_TIMER - TIMER :"
LOCATE 08,02 : PRINT "Power Basic TIMER :"
LOCATE 10,02 : PRINT " HR_TIMER -  TIME :"
LOCATE 12,02 : PRINT "Power Basic TIME$ :"

DO
   IF INSTAT THEN IF INKEY$ = CHR$(27) THEN EXIT LOOP

   LOCATE 06,24 : PRINT GetTime()
   LOCATE 08,24 : PRINT TIMER
   LOCATE 10,24 : PRINT MyTime(0)
   LOCATE 12,24 : PRINT TIME$
   DoSleep 0.010          ' Delay 10 milliseconds
LOOP

END

Hope be luck...

------------------
Gustavo Asplanatti
[email protected]

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