Using rdtsc for timing in our code...
'rdtsc' is one of the Intel assembly instructions, which we can use to get the
CPU tick-count. It only takes a couple of asm instructions to get it, and
we can use it to determine some basic runtime information if where in a hurry.
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int timeGetTime(void);
#pragma aux timeGetTime = ".586" "rdtsc"
value [eax] modify [edx]; |
Just take a looksy at that! If only all small C snippets where that
sweet. BUT! There is a bit of a drawback if you don't have the 'WATCOM
C/C++' compiler.... so I did a Visual C/C++ version as well :)
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int
inline
timeGetTime(void){
__asm{ rdtsc} } |
The rdtsc intel instruction, simply takes the tick count, which it keeps
track on, deep within itself....and puts it into the eax register. There
are lots of useful intel asm intructions if you look around another example 'cpuid'
which gives your CPU chip number....as each cpu chip has its own number given to
it when its born.
| Snippet : code.cpp (view) |
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int
timeGetTime(void){
__asm{ rdtsc} }
// Program entry point
void
main()
{
int t, i;
printf("CPU Ticks %d \n", t = timeGetTime() );
printf("<small delay (100)>\n");
for( i=0; i<100; i++) ;
printf("(Difference in)CPU Ticks %d \n", timeGetTime()-t );
}// end main()
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