VHDL code to find square root of number? - vhdl

Question

Is there is any in built function or any library that can be included in the design to find square root of a number?

Answer 1

Restoring square root algorithm is easy to implement on fpga, wikipedia has an example.
FPGA vendors should have cores available, it hides inside the general purpose CORDIC core on Xilinx. They also have square root cores for floating points, if that's what you need.

Answer 2

For non-synthesizable (simulation/test-bench only) operation, square root for real can be done with:
y := math_real.sqrt(x)
For synthesizable operation, see answer from Jonathan Drolet.

Answer 3

This one worked for me.
library ieee;
use ieee.std_logic_1164.all;
use IEEE.STD_LOGIC_unsigned.ALL;
entity squart is port(
clock : in std_logic;
data_in : in std_logic_vector(7 downto 0);
data_out : out std_logic_vector(3 downto 0)); end squart;
architecture behaviour of squart is
signal part_done : std_logic := '0';
signal part_count : integer := 3;
signal result : std_logic_vector(4 downto 0) := "00000";
signal partialq : std_logic_vector(5 downto 0) := "000000";
begin
part_done_1: process(clock, data_in, part_done)
begin
if(clock'event and clock='1')then
if(part_done='0')then
if(part_count>=0)then
partialq(1 downto 0) <= data_in((part_count*2)+ 1 downto part_count*2);
part_done <= '1'; else
data_out <= result(3 downto 0);
end if;
part_count <= part_count - 1;
elsif(part_done='1')then
if((result(3 downto 0) & "01") <= partialq)then
result <= result(3 downto 0) & '1';
partialq(5 downto 2) <= partialq(3 downto 0) - (result(1 downto 0)&"01");
else
result <= result(3 downto 0) & '0';
partialq(5 downto 2) <= partialq(3 downto 0);
end if;
part_done <= '0';
end if;
end if;
end process;
end behaviour;

Answer 4

Check this one:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;
entity SQRT is
Generic ( b : natural range 4 to 32 := 16 );
Port ( value : in STD_LOGIC_VECTOR (15 downto 0);
result : out STD_LOGIC_VECTOR (7 downto 0));
end SQRT;
architecture Behave of SQRT is
begin
process (value)
variable vop : unsigned(b-1 downto 0);
variable vres : unsigned(b-1 downto 0);
variable vone : unsigned(b-1 downto 0);
begin
vone := to_unsigned(2**(b-2),b);
vop := unsigned(value);
vres := (others=>'0');
while (vone /= 0) loop
if (vop >= vres+vone) then
vop := vop - (vres+vone);
vres := vres/2 + vone;
else
vres := vres/2;
end if;
vone := vone/4;
end loop;
result <= std_logic_vector(vres(result'range));
end process;
end;