• Arthur Becker <artbeck hotmail.com> Feb 14 2007
• Heinz Saathoff <newshsaat arcor.de> Feb 16 2007

Arthur Becker <artbeck hotmail.com> writes:

Hi,

I love DMC and am (slowly) getting used to doing some programming in ASM as
well.  I am trying to figure out that processor speed by using rdtsc and then
keeping a counter outside of that.
The problem I run into is that for some reason I can't correctly get the BIOS
tick count on two separate Intel machines.  I have tried a crap load of
different ways to reference the same memory.
Here is the code and the output is the same number over and over no matter how
many times I run the program.  Your help getting my head "out" would be much
appreciated.  BTW, I took this example code from the Intel CPU identification
and CPUID instruction document.

	static unsigned int SEG_BIOS_DATA_AREA = 0x040;
	static unsigned int OFFSET_TICK_COUNT = 0x06c;
unsigned int testVal;
asm
{
			push SEG_BIOS_DATA_AREA
			pop es
			mov esi, OFFSET_TICK_COUNT
// The BIOS tick count updates
			mov ebx, DWORD PTR es:[esi]
// ~ 18.2 times per second.
			mov testVal,ebx
}
printf("Time Value:%u",testVal);

Heinz Saathoff <newshsaat arcor.de> writes:

Hello,

Arthur Becker schrieb...
 I love DMC and am (slowly) getting used to doing some programming in ASM as
 well.  I am trying to figure out that processor speed by using rdtsc and then
 keeping a counter outside of that.
 The problem I run into is that for some reason I can't correctly get the BIOS
 tick count on two separate Intel machines.  I have tried a crap load of
 different ways to reference the same memory.
 Here is the code and the output is the same number over and over no matter how
 many times I run the program.  Your help getting my head "out" would be much
 appreciated.  BTW, I took this example code from the Intel CPU identification
 and CPUID instruction document.
 
 	static unsigned int SEG_BIOS_DATA_AREA = 0x040;
 	static unsigned int OFFSET_TICK_COUNT = 0x06c;
 unsigned int testVal;
 asm
 {
 			push SEG_BIOS_DATA_AREA
 			pop es
 			mov esi, OFFSET_TICK_COUNT
 // The BIOS tick count updates
 			mov ebx, DWORD PTR es:[esi]
 // ~ 18.2 times per second.
 			mov testVal,ebx
 }
 printf("Time Value:%u",testVal);


Which memory model do you use? This example will not work with the DOS 
extented (Option -mx) or as a Windows  application. 

If you compile this example with dmc -ms t.c you will get the ticker:

/****************  t.c ***********************/
#include <stdio.h>

unsigned int GetBiosTicker()
{  unsigned int btick;
   asm {
      mov   ax,0x0040
      mov   es,ax
      mov   si,0x006c
      mov   ax,es:[si]
      mov   btick,ax
   }
   return btick;
}//GetBiosTicker


int main()
{  printf("Bios-Tick = %u\n", GetBiosTicker());
   return 0;
}
/**************** end t.c ***********************/


- Heinz