blob: 01549ed0e95d82062c1f92b4201ea73f21034824 (
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
53
54
55
56
57
58
59
60
61
62
63
64
|
library ieee;
use ieee.std_logic_1164.all;
library ieee;
use ieee.numeric_std.all;
entity sub_206 is
port (
gt : out std_logic;
output : out std_logic_vector(40 downto 0);
sign : in std_logic;
in_b : in std_logic_vector(40 downto 0);
in_a : in std_logic_vector(40 downto 0)
);
end sub_206;
architecture augh of sub_206 is
signal carry_inA : std_logic_vector(42 downto 0);
signal carry_inB : std_logic_vector(42 downto 0);
signal carry_res : std_logic_vector(42 downto 0);
-- Signals to generate the comparison outputs
signal msb_abr : std_logic_vector(2 downto 0);
signal tmp_sign : std_logic;
signal tmp_eq : std_logic;
signal tmp_le : std_logic;
signal tmp_ge : std_logic;
begin
-- To handle the CI input, the operation is '0' - CI
-- If CI is not present, the operation is '0' - '0'
carry_inA <= '0' & in_a & '0';
carry_inB <= '0' & in_b & '0';
-- Compute the result
carry_res <= std_logic_vector(unsigned(carry_inA) - unsigned(carry_inB));
-- Set the outputs
output <= carry_res(41 downto 1);
-- Other comparison outputs
-- Temporary signals
msb_abr <= in_a(40) & in_b(40) & carry_res(41);
tmp_sign <= sign;
tmp_eq <= '1' when in_a = in_b else '0';
tmp_le <=
tmp_eq when msb_abr = "000" or msb_abr = "110" else
'1' when msb_abr = "001" or msb_abr = "111" else
'1' when tmp_sign = '0' and (msb_abr = "010" or msb_abr = "011") else
'1' when tmp_sign = '1' and (msb_abr = "100" or msb_abr = "101") else
'0';
tmp_ge <=
'1' when msb_abr = "000" or msb_abr = "110" else
'1' when tmp_sign = '0' and (msb_abr = "100" or msb_abr = "101") else
'1' when tmp_sign = '1' and (msb_abr = "010" or msb_abr = "011") else
'0';
gt <= not(tmp_le);
end architecture;
|
