Concurrent Rules

concurrent_001

This rule checks the indent of concurrent assignments.

Violation

architecture RTL of FIFO is
begin

     wr_en <= '0';
rd_en <= '1';

Fix

architecture RTL of FIFO is
begin

  wr_en <= '0';
  rd_en <= '1';

concurrent_002

This rule checks for a single space after the <= operator.

Violation

wr_en <=    '0';
rd_en <=   '1';

Fix

wr_en <= '0';
rd_en <= '1';

concurrent_003

This rule checks alignment of multiline concurrent assignments. Succesive lines should align to the space after the assignment operator. However, there is a special case if there are parenthesis in the assignment. If the parenthesis are not closed on the same line, then the next line will be aligned to the parenthesis. Aligning to the parenthesis improves readability.

Violation

wr_en <= '0' when q_wr_en = '1' else
     '1';

w_foo <= I_FOO when ((I_BAR = '1') and
         (I_CRUFT = '1')) else
         '0';

O_FOO <= (1 => q_foo(63 downto 32),
         0 => q_foo(31 downto  0));

n_foo <= resize(unsigned(I_FOO) +
         unsigned(I_BAR), q_foo'length);

Fix

wr_en <= '0' when q_wr_en = '1' else
         '1';

w_foo <= I_FOO when ((I_BAR = '1') and
                     (I_CRUFT = '1')) else
         '0';

O_FOO <= (1 => q_foo(63 downto 32),
          0 => q_foo(31 downto  0));

n_foo <= resize(unsigned(I_FOO) +
                unsigned(I_BAR), q_foo'length);

concurrent_004

This rule checks for at least a single space before the <= operator.

Violation

wr_en<= '0';

Fix

wr_en <= '0';

concurrent_005

This rule checks for labels on concurrent assignments. Labels on concurrents are optional and do not provide additional information.

Violation

WR_EN_OUTPUT : WR_EN <= q_wr_en;
RD_EN_OUTPUT : RD_EN <= q_rd_en;

Fix

WR_EN <= q_wr_en;
RD_EN <= q_rd_en;

concurrent_006

This rule checks the alignment of the <= operator over multiple consecutive lines.

Violation

wr_en <= '0';
rd_en   <= '1';
data <= (others => '0');

Fix

wr_en   <= '0';
rd_en   <= '1';
data    <= (others => '0');

concurrent_007

This rule checks for code after the else keyword.

Violation

wr_en <= '0' when overflow = '0' else '1';

Fix

wr_en <= '0' when overflow = '0' else
         '1';

concurrent_008

This rule checks the alignment of inline comments in sequential concurrent statements.

Violation

wr_en   <= '0';    -- Write enable
rd_en   <= '1';  -- Read enable
data    <= (others => '0');   -- Write data

Fix

wr_en   <= '0';               -- Write enable
rd_en   <= '1';               -- Read enable
data    <= (others => '0');   -- Write data