After Rules

after_001

This rule checks for after x in signal assignments in clock processes.

Violation

clk_proc : process(clock, reset) is
begin
  if (reset = '1') then
    a <= '0';
    b <= '1';
  elsif (clock'event and clock = '1') then
    a <= d;
    b <= c;
  end if;
end process clk_proc;

Fix

clk_proc : process(clock, reset) is
begin
  if (reset = '1') then
    a <= '0';
    b <= '1';
  elsif (clock'event and clock = '1') then
    a <= d after 1 ns;
    b <= c after 1 ns;
  end if;
end process clk_proc;

Note

This rule has two configurable items:

• magnitude

• units

The magnitude is the number of units. Default is 1.

The units is a valid time unit: ms, us, ns, ps etc… Default is ns.

after_002

This rule checks the after keywords are aligned in a clock process.

Refer to Configuring Keyword Alignment Rules for information on changing the configurations.

Violation

clk_proc : process(clock, reset) is
begin
  if (reset = '1') then
    a <= '0';
    b <= '1';
  elsif (clock'event and clock = '1') then
    a <= d     after 1 ns;
    b <= c   after 1 ns;
  end if;
end process clk_proc;

Fix

clk_proc : process(clock, reset) is
begin
  if (reset = '1') then
    a <= '0';
    b <= '1';
  elsif (clock'event and clock = '1') then
    a <= d     after 1 ns;
    b <= c     after 1 ns;
  end if;
end process clk_proc;

after_003

This rule checks the after keywords do not exist in the reset portion of a clock process.

Violation

clk_proc : process(clock, reset) is
begin
  if (reset = '1') then
    a <= '0' after 1 ns;
    b <= '1' after 1 ns;
  elsif (clock'event and clock = '1') then
    a <= d after 1 ns;
    b <= c after 1 ns;
  end if;
end process clk_proc;

Fix

clk_proc : process(clock, reset) is
begin
  if (reset = '1') then
    a <= '0';
    b <= '1';
  elsif (clock'event and clock = '1') then
    a <= d  after 1 ns;
    b <= c  after 1 ns;
  end if;
end process clk_proc;