VHDL: Assigning elements from a 2D array to 1D array

Question

I have a 2D array of records which I have to select column by column for processing. I am marshaling the column records into a column array, something like this:

col_array(0) <= ( td_array(0)(0), td_array(1)(0), td_array(2)(0), td_array(3)(0) );

Essentially an array append operation.

I have several arrays like this. Is this possible to do with a for-generate loop ?

This looks like an array append kind of operation. How do you do this ?

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Addenda: Each record in the 2D array looks like:

type foo is record:
  enable : std_logic;
  index  : std_logic_vector(7 downto 0);
  cmd    : std_logic_vector(2 downto 0);
end record;

So I will have interfaces like these in a row-column arrangement:

30  31  32
20  21  22   
10  11  12
00  01  02

I will need to break-out the record signals by the column (using a multiplexer). So (00, 10, 20, 30) will be accessed on the output of a MUX.

Answer 1

Not quite sure of the actual usage you are looking for (how does the index of col_array relate to the indices of td_array if at all), but does this help? (I've rearranged things as a 2-d array rather than a vector of vectors)

architecture a1 of test is
    type std_ulogic_2d is array(natural range <>, natural range <>) of std_ulogic;
    signal td_array : std_ulogic_2d(0 to 3, 0 to 4);
    signal col_array : std_ulogic_vector(td_array'range(1));
begin  -- architecture a1
    iloop : for i in td_array'range(1) generate
        col_array(i) <= td_array(i,0);
    end generate;
end architecture a1;