-- mul32c_test.vhdl   test entity mul32c--signal a[32];  multiplier--signal b[32];  multiplicand--signal c[64];  productlibrary STD;use STD.textio.all;library IEEE;use IEEE.std_logic_1164.all;use IEEE.std_logic_textio.all;use IEEE.std_logic_arith.all;entity mul32c_test isend mul32c_test;architecture circuits of mul32c_test is  signal cntr : std_logic_vector(3 downto 0) := B"0001";  signal a    : std_logic_vector(31 downto 0) := X"00000000";  signal b    : std_logic_vector(31 downto 0) := X"00000000";  signal prod : std_logic_vector(63 downto 0);  component mul32c   -- 32 x 32 = 64 bit product multiplier    port(a    : in  std_logic_vector(31 downto 0);  -- multiplicand         b    : in  std_logic_vector(31 downto 0);  -- multiplier         prod : out std_logic_vector(63 downto 0)); -- product  end component mul32c;  procedure my_printout(a   : std_logic_vector(31 downto 0);                        b   : std_logic_vector(31 downto 0);                        prod: std_logic_vector(63 downto 0)) is    variable my_line : line;    alias swrite is write [line, string, side, width] ;  begin    swrite(my_line, "a=");    hwrite(my_line, a);    swrite(my_line, ", b=");    hwrite(my_line, b);    swrite(my_line, ",  prod=");    hwrite(my_line, prod);    swrite(my_line, ", cntr=");    write(my_line, cntr);    swrite(my_line, ",  at=");    write(my_line, now);    writeline(output, my_line);    writeline(output, my_line); -- blank line  end my_printout;  begin  -- circuits of mul32c_test  mult32:  mul32c port map(a, b, prod); -- parallel circuit  driver: process                      -- serial code            variable my_line : LINE;          begin  -- process driver            write(my_line, string'("Driver starting."));            writeline(output, my_line);                        for i in 0 to 4 loop              a( 3 downto  0) <= cntr; -- or "0001";              a( 7 downto  4) <= cntr;              a(11 downto  8) <= cntr;              a(15 downto 12) <= cntr;              a(19 downto 16) <= cntr;              a(23 downto 20) <= cntr;              a(27 downto 24) <= cntr;              a(31 downto 28) <= cntr;              b( 3 downto  0) <= cntr;              b( 7 downto  4) <= cntr;              b(11 downto  8) <= cntr;              b(15 downto 12) <= cntr;              b(19 downto 16) <= cntr;              b(23 downto 20) <= cntr;              b(27 downto 24) <= cntr;              b(31 downto 28) <= cntr;              wait for 319 ns;  -- pseudo clock wait for propogation              my_printout(a, b, prod);  -- write output              cntr <= unsigned(cntr) + unsigned(cntr);              wait for 1 ns;            end loop;  -- i            a <= x"FFFFFFFF";            b <= x"FFFFFFFF";            wait for 319 ns;  -- pseudo clock wait for propogation            my_printout(a, b, prod);  -- write output            cntr <= unsigned(cntr) + unsigned(cntr);            a <= x"7FFFFFFF";            b <= x"7FFFFFFF";            wait for 319 ns;  -- pseudo clock wait for propogation            my_printout(a, b, prod);  -- write output            cntr <= unsigned(cntr) + unsigned(cntr);          end process driver;end architecture circuits; -- of mul32c_testconfiguration mul32c_config of mul32c_test is  for circuits -- of mul32c_test    for all: mul32c      use entity WORK.mul32c(circuits);                for circuits -- of mul32c        for stage            for all: add32csa            use entity WORK.add32csa(circuits);            for circuits -- of add32csa              for stage                  for all: fadd                  use entity WORK.fadd(circuits);                end for;              end for;            end for;          end for;        end for;        for all: add32csa          use entity WORK.add32csa(circuits);          for circuits -- of add32csa            for stage                for all: fadd                use entity WORK.fadd(circuits);              end for;            end for;          end for;        end for;        for all: add32          use entity WORK.add32(circuits);          for circuits -- of add32            for all: add4              use entity WORK.add4(circuits);              for circuits -- of add4                for all: fadd                  use entity WORK.fadd(circuits);                end for;              end for;            end for;          end for;        end for;      end for;      end for;  end for;end configuration mul32c_config;