Forum Discussion
Altera_Forum
Honored Contributor
15 years agoDevide in VHLD
I want to implement this function : A<= B/x"A", when I compile, the Quartus put a notice: "/" used but didn't declare. When I try with "*" (multiply) or "+" (add), it is ok. I don't know this er...
Altera_Forum
Honored Contributor
15 years agoAlt first sight, the result_out waveform seems not to fit the above design (it may be still possible under specific conditions). result_out is a registered signal, clocked by the 100 MHz clock, but it changes shortly before the next rising edge, usually causing a setup violation for the following logic. Without knowing the previous states of all signals, and the timing constraints in effect, I can only guess about the reason for this behaviour.
I also don't understand the purpose of the strange method to do a signed multiplication. The ABS() function is by the way causing an overflow for the most negative number -32768 (0x8000), which hasn't a corresponding positive value. P.S.: I see, that a similar negation method has been used previously in the thread. It may be a workaround for algorithms, that aren't avaliable for negative numbers for some reason. But multiply is.