I have an idea for a different solution.. (I just came up with this on my
afternoon break, so give me credit here 8-) ) I can't be bothered writing
actual code, so this is just a rough idea of the actual code... It's
basically a binary search for the loop value which causes a delay of one
"Tick"
/*BEGIN CODE*/
low = 1;
high = 1000000; // This should be high enough so that at least ONE tick
occurs during this many iterations of the loop
while (high > low) {
x = ( high + low ) / 2;
s = TimGetTicks();
do {
t = TimGetTicks();
} while (t == s);
// A tick *just* occurred. Now we count until the next.
while (x) x--; // The delay loop
if (t == TimGetTicks()) {
low = x+1; // Less than a tick occurred during delay, so try again,
but wait longer.
}
else {
high = x-1;// A tick occurred, so we're over. Try again, but wait
less time.
}
}
d = ( x * SysTicksPerSecond() ) / 1000;
/*END CODE*/
NOTE: This code is *guaranteed* to be bug-ridden, it's just intended to
convey the rough idea I just had.
The result *should* be a value for d which causes the delay loop to wait one
milisecond.
Let me know what you think, or if I'm just a barfing idiot.. (Which is more
than likely).. 8-)
Regards,
Alan Ingleby
Systems Developer
ProfitLink Consulting Pty Ltd
309 Burwood Road
Hawthorn
Victoria 3122
Australia
"Bill Shaw" <[EMAIL PROTECTED]> wrote in message news:42184@palm-dev-forum...
>
> Needing a millisecond delay routine for my smart card application, I
> searched the archives and found others asking for a similar routine.
> The reply was always negative; doesn't exist, can't do it. Not being
> one to take no for an answer ;-) I thought about it for a few minutes
> and came up with this solution. The timing is not perfect, and shorter
> delays will be less accurate due to interrupts, but it's close enough
> for my needs.
>
> Enjoy.
>
> bs
>
>
>
/***************************************************************************
**
> *
> * File Name: delay.c
> * Millisecond delay routines.
> *
> * Author: Bill Shaw
> * [EMAIL PROTECTED]
> * Westbrook Systems:
> * Windows, Mac OS, Palm, PIC, and smart card development
> *
> * Date: 2/23/01
> *
>
****************************************************************************
***
> *
> * This code is emailware. If you find if useful, send me an email
> * and tell me about your app!
> *
> * Also, please leave my headers intact. This is one form of
advertising
> * I like to take advantage of when I can!
> *
>
****************************************************************************
***
> */
> #include <PalmOS.h>
>
> UInt32 startTicks; // the time we started
> UInt32 loopsPerMs; // # loops per millisecond
> UInt32 endTicks; // the time we ended
>
>
/***************************************************************************
****
> *
> * calcDelay - Calculates the delay value (loopsPerMs) for this Palm.
> * Call once during app initialization.
> * returns - nothing
> *
>
****************************************************************************
***
> */
> void calcDelay(void)
> {
> UInt32 ticksPerSec;
> UInt32 loopCount;
>
> ticksPerSec = SysTicksPerSecond(); // get # ticks per second
> startTicks = TimGetTicks(); // get start time
>
> endTicks = startTicks + ticksPerSec; // calc end time
>
> // run the timing loop...
> for (loopCount=0; TimGetTicks() < endTicks; loopCount++) {
> ticksPerSec++;
> }
>
> endTicks = TimGetTicks(); // get end time (for debug)
> loopsPerMs = loopCount / 1000; // calc # loops/ms
>
> } // end of calcDelay()
>
>
/***************************************************************************
****
> *
> * msDelay - millisecond delay
> * UInt32 ms = # milliseconds to delay
> * returns - nothing
> *
>
****************************************************************************
***
> */
> void msDelay(UInt32 ms)
> {
> UInt32 loopCount, i;
>
> loopCount = loopsPerMs * ms; // calc # loops
>
> startTicks = TimGetTicks(); // get start time (for debug)
>
> // run the delay loop...
> for (i=0; i<loopCount; i++) {
> endTicks = TimGetTicks();
> }
>
> i = 0; // just to break on
>
> }
>
> // end of file delay.c
>
>
>
>
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