sleep or delay function help

[EclipseOS]

Hey
I have a sleep code that works fine on my 486 test computer, but when I try it on my athlon xp 2000+ (1667 mhz) it doesn't delay the full, 10 or 5 seconds or watever I tell it to wait.

here's my delay code:

void delay(int secs)
{
int x;
while (secs--)
{
x = bios_call(0);
while (bios_call(0) == x);
}
return;
}


inline static unsigned short bios_call(int data_a)
{
int data_b;
outportb(0x70, data_a);
data_b = inportb(0x71);
return data_b;
}
#endif

I want to know if my delay function works so that I can try and figure out a way to use it to find the cpu speed.

Thanx

[DennisCGc]

I want to know if my delay function works so that I can try and figure out a way to use it to find the cpu speed.

It should work, I think
There was a whole thread about this, but see the OSFaq.

HTH

[Ozguxxx]

I did not really konw aobut port 70 but is your time granularity same in both computers, I mean do you program pit or any other timer so that your are counting for same and correct granularity?

[DennisCGc]

I did not really konw aobut port 70 but is your time granularity same in both computers, I mean do you program pit or any other timer so that your are counting for same and correct granularity?

Port 0x70 is used for the RTC.

[EclipseOS]

I am grabbing the seconds from the RTC (0x70, 0x00) and using them to time a delay. I've used the RTC to make a time function that tells the time and it works fine on both computers. So if this won't work, what else could I do for a sleep() function? Thanx for your replys.

[DennisCGc]

I am grabbing the seconds from the RTC (0x70, 0x00) and using them to time a delay. I've used the RTC to make a time function that tells the time and it works fine on both computers. So if this won't work, what else could I do for a sleep() function? Thanx for your replys.

Try using the timer interrupt instead.
Normal, it's programmed that it's called 18.2 times a second, but you can reprogram the PIT to reset that ;D

[EclipseOS]

What is a PIT and what does it do? (Sorry, I'm new at this)
How do I program a timer interrupt? I know that u use IRQ 0, but I'm not exactly sure how. I do better at understanding things if I can have a piece of code to look at that is not too complicated. Thanx

[DennisCGc]

PIT=Programmable Interrupt Timer, this chip calls the IRQ0 routine.
What you put in that routine, is totally up to you.
You can have a look at http://www.execpc.com/~geezer , or do a good search on this board, there are a lot of this related questions (maybe in the FAQ ??? )

HTH, DennisCGc.

[EclipseOS]

Finially got it to work right. It works the same on both computers now.Thanx for your help. Now how can I use sleep(int sec) to detect CPU speed? I looked at the FAQ and lots of other places, but I couldn't get it to work right. Anyone who has a working code, could you please show me an example? C or C++ code would be appreciated, thanx again.

[Pype.Clicker]

doesn't the good old

Code: Select all

    delay(1);
    long long before=rdtsc();
    delay(1);
    long long after=rdtsc();
    long mhz = (after-before) / 1000000;

work ?

(well, there are little chance it will since (long long)/(long) may require a math library if the compiler doesn't see it can do it without ...)

[EclipseOS]

what does rdtsc() do? Like I've seen that piece of code many times before I just don't know what the rdtsc contains.

[Curufir]

The Pentium-Pro (And above) contain a counter which increments for every processor cycle. The RDTSC instruction reads this 64-bit value (It gets returned in 2 registers, EDX and EAX I seem to recall). Once you know how many cycles pass in a specific time working out the frequency becomes trivial.

[EclipseOS]

ya, but what I want is:

void rdtsc()
{
....
}

[virusx]

if you are using gcc.

Code: Select all

void  rdtsc()
{
      unsigned int slow, shigh;
      unsigned int elow, ehigh;
      unsigned long long start=0, end=0, result;
asm(
                "rdtsc\t\n"
                :"=a"(slow), "=d"(shigh)
                :
          );
      
sleep(1); /* in secs */

asm(
                "rdtsc\t\n"
                :"=a"(elow), "=d"(ehigh)
                :
          );
      start |= shigh;
      start <<= 32;
      start |= slow;

      end |= ehigh;
      end <<= 32;
      end |= elow;

      result = ((end - start)/1)/1000000;
      printf("%ld MHZ\n",result);

}

[Candy]

Code: Select all

void  rdtsc()
{
      union {
          struct {
              unsigned int low, high;
          } split;
          unsigned long long total;
      } start = 0, end = 0;
      unsigned int result;

asm(
                "rdtsc\t\n"
                :"=a"(start.split.low), "=d"(start.split.high)
                :
          );
      
sleep(1); /* in secs */

asm(
                "rdtsc\t\n"
                :"=a"(end.split.low), "=d"(end.split.high)
                :
          );

      result = ((end - start)/1)/1000000;
      printf("%ld MHZ\n",result);

}

if you're using GCC anyway...