How could I make a adjustable delay function in "micro-second" level

You might try a series of _nops_, and jump far enough down into them so that the remainder represents the time that you need.

There is still some overhead in this method, of course. You have to calculate the jump, and get into and out of the function. You won't be able to create a 1 us delay, but you might be able to create fairly precise delays from, say, 10 us up to as long of a table as you can stand.

Longer intervals means you can use a loop, at the cost of more granularity and more overhead.

Small intervals and precise measurements are best done by timer hardware rather than software. "Small" is relative to your processor clock and architecture. If software has to act at very precise times (send this response exactly 3.4 microseconds after receiving this message), then you need a faster processor, as Andrew suggests. There is an overall system design issue to be considered here, so it's hard to suggest solutions without really knowing the requirements.

You might try a series of _nops_, and jump far enough down into them so that the remainder represents the time that you need.

There is still some overhead in this method, of course. You have to calculate the jump, and get into and out of the function. You won't be able to create a 1 us delay, but you might be able to create fairly precise delays from, say, 10 us up to as long of a table as you can stand.

Longer intervals means you can use a loop, at the cost of more granularity and more overhead.

Small intervals and precise measurements are best done by timer hardware rather than software. "Small" is relative to your processor clock and architecture. If software has to act at very precise times (send this response exactly 3.4 microseconds after receiving this message), then you need a faster processor, as Andrew suggests. There is an overall system design issue to be considered here, so it's hard to suggest solutions without really knowing the requirements.

I want to delay according to the parameter I pass.My goal is to modify delay time for some protocol time slot testing.


For delays this short the only option is inline nop.

two possibilities

1) Since you refer to "testing" could you use a conditional assembly.

2) Selecting the routine instead of selecting the delay:

do_it_with_1
mov...
...
....
...
nop
...
...
...
...
ret

do_it_with_2
mov...
...
....
...
nop
nop
...
...
...
...
ret

Erik

oh, even easier
do_it_with_1
MACRO_1
nop
MACRO_2

do_it_with_2
MACRO_1
nop
nop
MACRO2

Erik