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Altera_Forum's avatar
Altera_Forum
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12 years ago

processes: while loop does not work, for loop does work. Why?

I want to write this code for a basic synchronous counter more efficiently... u_count: process(rst_i, clk_i) -- generated on rising edge variable i: integer :=1; begin if rst_i = '1' ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

The while loop could be used to wait on a signal: 


process(clk)
begin
  if rising_edge(clk) then
    while some_input = 0 loop
      --do something
    end loop;
  end if;
end process;

THis is completly unsuitable for synthesis as it does not map to any real logic circuit. Its not an argument of While vs for - you can also write code that wont synthesis a for loop.