I am trying to use the function shift_left() in my project, but I'm getting 2 errors I can't explain:
Error: type error near 'shift left'; expected type 'std_logic_vector'
but temp IS a std_logic_vector!
Error: no feasible entry for subprogram 'shift_left' found
the signals used in the code are defined as:
signal shifted_pixel, temp : std_logic_vector(15 downto 0);
signal i_data : std_logic_vector(7 downto 0);
the snippet below is written within a process
temp <= "00000000" & i_data;
shifted_pixel <= shift_left(temp, 5);
full code below:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.numeric_std.ALL;
entity project is
port (
i_clk : in std_logic;
i_rst : in std_logic;
i_start : in std_logic;
i_data : in std_logic_vector(7 downto 0);
);
end project;
architecture rtl of project is
signal shifted_pixel, temp : std_logic_vector(15 downto 0);
begin
process(i_data)
begin
temp <= "00000000" & i_data;
shifted_pixel <= shift_left(temp, 5);
end process;
end rtl;
The shift_left function in numeric_std package takes an unsigned as first argument and it returns an unsigned value.
So you have to cast your values:
shifted_pixel <= std_logic_vector(shift_left(unsigned(temp), 5));
HTH
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.std_logic_arith.all;
use ieee.numeric_bit.all;
use ieee.numeric_std.all;
entity multiplexer is
port (
A,B: in std_logic_vector (7 downto 0);
CI: in std_logic;
CO: out std_logic;
ANS: out std_logic_vector (7 downto 0);
OP: in std_logic_vector(1 downto 0);
EN: in std_logic);
end multiplexer;
architecture archi of multiplexer is
signal tmp: std_logic_vector (8 downto 0);
begin
process (EN) begin
if (EN = '1') Then
case OP is
when "00" =>
tmp <= conv_std_logic_vector((conv_integer(A)+conv_integer(B)+conv_integer(CI)),9);
ANS<= tmp(7 downto 0);
CO <= tmp(8);
when "01" =>
tmp <= conv_std_logic_vector((conv_integer(A)-conv_integer(B)+conv_integer(CI)),9);
ANS<= tmp(7 downto 0);
CO <= tmp(8);
when others => NULL;
end case;
else
NULL;
end if;
end process;
end archi;
error is coming at line 19 No feasible entries for infix operator '=' also Type error resolving infix expression "=" as type std.STANDARD.BOOLEAN. Where am I going wrong?
wave output
Surely this:
EN: in std_logic_vector
should be this:
EN: in std_logic
Your error message is complaining that there is no "=" operator defined that can compare a std_logic_vector to a '1', which is a literal of type std_logic.
I'm writing something in VHDL about an essay and I'm facing a strange situation. I've written some components, simulated and tested them, and everything seems to works fine. However, when simulating the top entity, I'm getting zeros as a result! Please take a look at the following listings:
Top Entity:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
entity foobar is
port ( data_i : in std_logic_vector(39 downto 0);
sum_12bit_o : out std_logic_vector(11 downto 0)
);
end foobar;
architecture Behavioral of foobar is
--Declare components
component four_10bit_word_adder is
port( --Input signals
a_byte_in: in std_logic_vector(9 downto 0);
b_byte_in: in std_logic_vector(9 downto 0);
c_byte_in: in std_logic_vector(9 downto 0);
d_byte_in: in std_logic_vector(9 downto 0);
cin: in std_logic;
--Output signals
val12bit_out: out std_logic_vector(11 downto 0)
);
end component;
-- Signal declaration
signal int: std_logic_vector(11 downto 0);
signal intdata: std_logic_vector(39 downto 0);
begin
intdata <= data_i; --DEBUG
U1: four_10bit_word_adder port map (intdata(39 downto 30), intdata(29 downto 20),
intdata(19 downto 10), intdata(9 downto 0),
'0', int);
end Behavioral;
four_10bit_word_adder:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
entity four_10bit_word_adder is
generic (
bits: integer := 10
);
port( --Input signals
a_byte_in: in std_logic_vector(bits-1 downto 0);
b_byte_in: in std_logic_vector(bits-1 downto 0);
c_byte_in: in std_logic_vector(bits-1 downto 0);
d_byte_in: in std_logic_vector(bits-1 downto 0);
cin: in std_logic;
--Output signals
val12bit_out: out std_logic_vector(bits+1 downto 0)
);
end four_10bit_word_adder;
architecture Behavioral of four_10bit_word_adder is
-- Component Declaration
component compressor_4_2 is
port(a,b,c,d,cin : in std_logic;
cout, sum, carry : out std_logic
);
end component;
--------------------------------------------------------+
component generic_11bit_adder
port (
A: in std_logic_vector(10 downto 0); --Input A
B: in std_logic_vector(10 downto 0); --Input B
CI: in std_logic; --Carry in
O: out std_logic_vector(10 downto 0); --Sum
CO: out std_logic --Carry Out
);
end component;
--------------------------------------------------------+
-- Declare internal signals
signal int: std_logic_vector(bits-1 downto 0); -- int(8) is the final Cout signal
signal byte_out: std_logic_vector(bits-1 downto 0);
signal carry: std_logic_vector(bits-1 downto 0);
signal int11bit: std_logic_vector(bits downto 0);
-- The following signals are necessary to produce concatenated inputs for the 10-bit adder.
-- See the paper for more info.
signal Concat_A: std_logic_vector(bits downto 0);
signal Concat_B: std_logic_vector(bits downto 0);
signal co : std_logic;
begin
A0: compressor_4_2 port map (a_byte_in(0), b_byte_in(0),
c_byte_in(0), d_byte_in(0),
'0', int(0), byte_out(0), carry(0));
instances: for i in 1 to bits-1 generate
A: compressor_4_2 port map (a_byte_in(i), b_byte_in(i),
c_byte_in(i), d_byte_in(i), int(i-1),
int(i), byte_out(i), carry(i));
end generate;
R9: generic_11bit_adder port map (Concat_A, Concat_B, '0', int11bit, co);
Concat_A <= int(8) & byte_out;
Concat_B <= carry & '0';
process (co)
begin
if (co = '1') then
val12bit_out <= '1' & int11bit;
else
val12bit_out <= '0' & int11bit;
end if;
end process;
end Behavioral;
4:2 Compressor
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
entity compressor_4_2 is
port(a,b,c,d,cin : in std_logic;
cout, sum, carry : out std_logic
);
end compressor_4_2;
architecture Behavioral of compressor_4_2 is
-- Internal Signal Definitions
signal stage_1: std_logic;
begin
stage_1 <= d XOR (b XOR c);
cout <= NOT((b NAND c) AND (b NAND d) AND (c NAND d));
sum <= (a XOR cin) XOR stage_1;
carry <= NOT((a NAND cin) AND (stage_1 NAND cin) AND (a NAND stage_1));
end Behavioral;
Generic 11-bit Adder:
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity generic_11bit_adder is
generic (
bits: integer := 11
);
port (
A: in std_logic_vector(bits-1 downto 0);
B: in std_logic_vector(bits-1 downto 0);
CI: in std_logic;
O: out std_logic_vector(bits-1 downto 0);
CO: out std_logic
);
end entity generic_11bit_adder;
architecture Behavioral of generic_11bit_adder is
begin
process(A,B,CI)
variable sum: integer;
-- Note: we have one bit more to store carry out value.
variable sum_vector: std_logic_vector(bits downto 0);
begin
-- Compute our integral sum, by converting all operands into integers.
sum := conv_integer(A) + conv_integer(B) + conv_integer(CI);
-- Now, convert back the integral sum into a std_logic_vector, of size bits+1
sum_vector := conv_std_logic_vector(sum, bits+1);
-- Assign outputs
O <= sum_vector(bits-1 downto 0);
CO <= sum_vector(bits); -- Carry is the most significant bit
end process;
end Behavioral;
I've tried a ton of things, but without any success. Do you have any idea what am I doing wrong? Sorry for the long question and thank you for your time.
Take a look at your process to generate val12bit_out in your four_10bit_word_adder entity. It's missing an input.
Also, there are several other issues. Fixing this one issue will not fix everything. But once you fix it, I think things will be a lot more clear.
I am getting some erros that I cant make sense and was hoping I could get some help.
ERROR: [VRFC 10-469] cannot update 'in' object shift_reg [C:/Users/Darren/Desktop/project_6_1_3/project_6_1_3.srcs/sources_1/new/1Bit_delay_register.vhd:25]
ERROR: [VRFC 10-925] indexed name is not a std_logic_vector [C:/Users/Darren/Desktop/project_6_1_3/project_6_1_3.srcs/sources_1/new/1Bit_delay_register.vhd:27]
ERROR: [VRFC 10-1504] unit simple_one_bit_serial_shift_register_behavior ignored due to previous errors [C:/Users/Darren/Desktop/project_6_1_3/project_6_1_3.srcs/sources_1/new/1Bit_delay_register.vhd:16]
INFO: [VRFC 10-240] VHDL file C:/Users/Darren/Desktop/project_6_1_3/project_6_1_3.srcs/sources_1/new/1Bit_delay_register.vhd ignored due to errors
I have tried altering the code to suit but nothing works ! this is the code:
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity simple_one_bit_serial_shift_register is
port(
clk : in std_logic;
reset : in std_logic;
shift_in : in std_logic_vector(31 downto 0);
shift_reg : in std_logic_vector(1 downto 0);
shift_out : out std_logic_vector(31 downto 0)
);
end simple_one_bit_serial_shift_register;
architecture simple_one_bit_serial_shift_register_behavior of simple_one_bit_serial_shift_register is
begin
--signal shift_reg : std_logic_vector(31 downto 0);
--signal shift_in : std_logic;
--signal shift_out : std_logic;
process (clk)
begin
if rising_edge(clk) then
shift_reg <= shift_reg(30 downto 0) & shift_in;
end if;
shift_out <= shift_reg(31);
end process;
end simple_one_bit_serial_shift_register_behavior
;
In line 25 the input shift_reg port is assigned, using shift_reg <= ..., but it is not legal to assign to an input port.
In line 27 there is reference to bit 31 in shift_reg(31), but shift_reg only has index 1 and 0 in declaration with shift_reg : in std_logic_vector(1 downto 0);. And indexing a single bit like (31) has type std_logic, which does not match the std_logic_vector type of target shift_out.
Recently i'm using VHDL to write a 16-but RAM. My code is:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use IEEE.Numeric_Std.all;
entity RAM is
port(
PC_in: in std_logic_vector (5 downto 0);
EN_WR_in: in std_logic_vector (1 downto 0);
RAM_in : in std_logic_vector(15 downto 0);
RAM_out : out std_logic_vector(15 downto 0);
test : out integer
);
end RAM;
architecture Behavioral of RAM is
type ram_t is array (63 downto 0) of std_logic_vector(15 downto 0);
signal ram : ram_t;
begin
PROCESS (EN_WR_in)
BEGIN
if (EN_WR_in(1)='1') then
IF (EN_WR_in(0) = '1') THEN
ram(conv_integer(unsigned(PC_in))) <= RAM_in;
else
RAM_out <= ram(conv_integer(unsigned(PC_in)));
end if;
else
RAM_out <="ZZZZZZZZZZZZZZZZ";
end if;
END PROCESS;
ram(20) <= "0000100010010000";
end Behavioral;
The problem that i facing with is i need to set some constant data in the ram just like
ram(20) <= "0000100010010000";
But the constant data didn't exist during simulation. Is there any way to solve it?
Thanks.
You can initialize the ram when you declare it:
signal ram : ram_t := ( "0000100010010000", x"1234", ... );
or perhaps
signal ram : ram_t := ( 20 => "0000100010010000", others => (others=>'0') );