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Altera_Forum's avatar
Altera_Forum
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9 years ago

Array of integer to std_logic_vector !?

Hello guys !

Description : the input is an std_logic_vector ..... the outpout must be an std_logic_vector BUT,

I read every element of the input and check if it is '1' then write 1 to an array else write -1 .

the final array should be converted to an output which is an std_logic_vector !!!!

For example

INput : std_logic_vector (5 downto 0) :="010101";

====> array = { -1 1 -1 1 -1 1}

OUTput : std_logic_vector (5 downto 0);

What are the possible solution to go from array to my output?!!!

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    That sounds like a crazy idea. Why are you converting a 6 bit bus into a 12 bit bus (2 bits is required to cover 1 and -1) AND the original 6 bit data. Im guessing you're trying to find the number of 1s compared to number of 0s?

    anyway you can easily do it. 

    
type int_array_t is array(5 downto 0) of integer range -1 to 1;
signal my_ar : int_array_t;
...
for i in my_ar'range loop
  if input(i) = '0' then
    my_ar(i) = -1;
  elsif input(i) = '1' then
    my_ar(i) = 1;
  else --cover illegal states in simulation
    my_ar(i) = 0;
  end if;
end loop;
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    Obviously it is easy to do the 1 and -1 statements, I've already did it, BUT my problem is with the output of 12 bits !!! How to do it ?!

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    convert the integer to the signed type: 

    
use ieee.numeric_std.all;;
op : out signed(1 downto 0);
op <= to_signed(some_integer, op'length);

    Ill let you work out the arrays of 12 bits etc as I assume this is some assignment. There are plenty of VHDL tutorials out there.