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Altera_Forum
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15 years ago

Porting PIO C-code from ARM-7 to Nios II (SE1-board) + performance issue.

Hi all, I'm having a try at the moment to port my C-code from the arm-7 mcu, LPC-P2148 to Nios II, SE1-board , Cyclon-II, EP2C20F484C7. The arm-none-eabi-gcc compiler was used for the ARM-7 ...
Altera_Forum's avatar
Altera_Forum
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15 years ago

Actually the compiler will transform the loop you gave into: 

if (wait != 0) {
    do
        wait = wait - 1;
    while (wait != 0);
}
Depending on the code layout the first conditional might get optimised for the 'wait == 0' case.

You get better code from a do ... while () loop.

So you want while (--wait);

However, for the example code, the compiler knew the value of the constant, so won't have compiled the initial test.