asm time question

umka · Joined: 28 Aug 2007 Posts: 99 Location: New Zealand

I have been trying to optimize a piece of code I wrote by looking at the asm output of ccs but have a question about how long it will take to execute a piece of code.

1) With the " if (Servo_flag[1] == false) " it takes two lines of asm does that mean it takes 2 clock cycles to get through that statement if it doesnt match?

2) Because the second line is a goto does that mean it only takes 1 cycle if the statement is true?

3)If servo_flag 1 and servo_flag 2 are true how many cycles does it take to get thorught the code.

4) if servo_flag1 and 2 are false but the servo counts < val how many cycles does it take to get through the code?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Use the Stopwatch feature of the MPLAB simulator to count the instruction
cycles in your code. Put a breakpoint on the first if() statement in the
program below, and also put one on the while(1) line at the end
"Run" the program to the first breakpoint. Zero the Stopwatch. "Run"
the program to the 2nd breakpoint. Look at the number of usec that
it took to execute the code between those two breakpoints, by looking
in the Stopwatch window. Follow the instructions in this post:
http://www.ccsinfo.com/forum/viewtopic.php?t=38351
Remember to set the correct clock frequency in the Debugger Settings
menu. It must be the same as your #use delay() statement.

Notice how I have setup the desired test conditions by setting both
variables to "TRUE" before the if() code is entered. You can set them
to whatever you want, based on which part of the code you wish
to check the execution time for.