blob: 0b23642fd289455ca3a3a28ac944e20c0cac975c (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
library ieee;
use ieee.std_logic_1164.all;
entity testm is
port (clk : in std_logic;
data : in std_logic_vector(2+1 downto 0);
q1 : out std_logic_vector(3 downto 0)
);
end testm;
architecture rtl of testm is
-- img_log2 function
function tlog2(d : positive) return natural is
variable tmp : positive;
begin
tmp := 1;
for count in 0 to d loop
if (tmp >= d) then
return count;
end if;
tmp := tmp*2;
end loop;
return d;
end;
constant SBITS : integer := tlog2(16);
signal fred : std_logic_vector(SBITS - 1 downto 0);
begin
fred <= data;
process (fred)
begin
case (fred(1 downto 0)) is
when "00" =>
q1 <= data;
when "01" =>
q1 <= "0000";
when "10" =>
q1 <= data;
when others =>
q1 <= "1111";
end case;
end process;
end rtl;
|
