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bbs prng simulation done, but no result waveform

Altera_Forum
Honored Contributor II
1,443 Views

currently i am using Cyclone II family libraries to implement a bbs prng 

i have insert a coding that i copy from internet, but i quite confuse on understanding the coding 

 

the coding i'm using to make modification: 

 

library IEEE; 

use IEEE.STD_LOGIC_1164.ALL; 

use IEEE.STD_LOGIC_ARITH.ALL; 

use IEEE.STD_LOGIC_UNSIGNED.ALL; 

 

 

entity bbs is 

Port ( p : in integer; 

q : in integer; 

s : in integer; 

b : out STD_LOGIC_VECTOR(7 downto 0) ); 

end bbs; 

 

 

architecture Behavioral of bbs is 

begin 

 

 

process(p,q,s) 

variable x0,x1,s1,x_0:integer; 

constant p:integer:=11; 

constant q:integer:=19; 

constant n:integer:=551; 

variable b1:integer ; 

variable b2:std_logic; 

variable r:std_logic_vector(7 downto 0); 

 

 

begin 

s1:=s*s; 

x0:=s1 mod 1024; 

for i in 0 to 7 loop 

x_0:=x0*x0; 

x1:=x_0 mod 1024; 

b1:=x1 mod 2; 

if b1=1 then 

b2:='1'; 

else b2:='0'; 

end if; 

r(6):=r(7); 

r(5):=r(6); 

r(4):=r(5); 

r(3):=r(4); 

r(2):=r(3); 

r(1):=r(2); 

r(0):=r(1); 

r(7):=b2;--so it will be serially transmitted but parallelly observed 

x0:=x1; 

b<=r; 

end loop; 

end process; 

end Behavioral; 

 

 

 

please if there is someone can help me on explaining the coding?
0 Kudos
4 Replies
Altera_Forum
Honored Contributor II
115 Views

Hi, 

 

Try to simulate and understand the operation, Also refer the following points, 

 

In given code input ‘s’ has significance. 

Check operation of Mod operator. 

When s=0 leads to b1=0 so b2 =0 hence r<=b<=00000000, 

When s=1 leads to b1=1 so b2 =1 hence r<=b<=11111111. 

 

--- Quote Start ---  

r(7):=b2;--so it will be serially transmitted but parallelly observed  

--- Quote End ---  

 

In for loop, eventually output vector b (b<=r) is updated, Check screen shot. 

 

Let me know if this has helped resolve the issue you are facing or if you need any further assistance. 

 

Best Regards 

Vikas Jathar  

Intel Customer Support – Engineering 

(Under Contract to Intel)
Altera_Forum
Honored Contributor II
115 Views

hi jatharvk, thanks for your information 

i refer to your sreenshot, how you assign the input p, q, and s as 1 bit? 

because when i assign p, q and s node into the quartus II waveform window, it show 3 of these nodes are in 32 bits 

and since i need my output should be in random value, the output result is only showed as "00000000" and "11111111" 

how can i modify it to show the output in random value form?
Altera_Forum
Honored Contributor II
115 Views

Hi, 

 

 

--- Quote Start ---  

how you assign the input p, q, and s as 1 bit? 

--- Quote End ---  

 

 

No, in the code p, q, s are declared as integer, check screen shot. Output of the given code either 00000000 or 11111111. It depends on the value of b1. 

 

 

--- Quote Start ---  

how can i modify it to show the output in random value form? 

--- Quote End ---  

 

Refer attached IEEE paper & modify your code. 

 

 

Let me know if this has helped resolve the issue you are facing. 

 

Best Regards 

Vikas Jathar  

Intel Customer Support – Engineering 

(Under Contract to Intel)
Altera_Forum
Honored Contributor II
115 Views

 

--- Quote Start ---  

Hi, 

 

 

 

No, in the code p, q, s are declared as integer, check screen shot. Output of the given code either 00000000 or 11111111. It depends on the value of b1. 

 

 

Refer attached IEEE paper & modify your code. 

 

 

Let me know if this has helped resolve the issue you are facing. 

 

Best Regards 

Vikas Jathar  

Intel Customer Support – Engineering 

(Under Contract to Intel) 

--- Quote End ---  

 

 

hi jatharvk, thanks for your helping, seen i just try to design the bbs algorithm, now i will use back my lfsr prng design to continue my FYP project 

appreciate for your helping 

 

Your sincerely 

Vahn Heng
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