Description

When I port an existing design from EDK 6.3 to EDK 8.1i and recompile the C Code, the inferred delay in the C Code is optimized away and the system does not behave properly anymore.

Solution

When the delay is inferred using a simple for() Loop, during the compilation of the C Code and after some Loop Collapsing Algorithm applied by the Compiler, the While Loop is optimized.

Using the C Keyword "Volatile" on the integer being incremented in the for() Loop should fix the problem:

Before:

"

int i;

for (i=0; i<100000; i++);

"

To fix it:

"

volatile int i;

for (i=0; i<100000; i++);

"