matrix entry in vhdl

[ammassk]

Hi all
How can I store a matrix which has 4 rows and 8 columns in memory? Each element in the matrix is character 0 or 1.

 

[TrickyDicky]

so basically its just 4x 8bit words - 32 bits? its not very big, you could just store it in a single register.

 

[ammassk]

each element is a character. I represented array as shown below.

type hmatrix_array is array(integer range 0 to 3 , integer range 0 to 7)of character;
constant mem:hmatrix_array:=("01011001","11100100","00100111","10011010");

But this is showing error.I need to access each element in this matrix.Please give me the correct syntax to represent this matrix.

 

[TrickyDicky]

the character type is literally that, characters, like 'a', 'c', '5' etc. They have no numerical value. What you have is an array of 4x8 std_logic_vectors. so try:

type hmatrix_array is array(0 to 3, 0 to 7) of std_logic_vector(7 downto 0);

 

[FvM]

What you have is an array of 4x8 std_logic_vectors.

It's not a 4x8 array of std_logic_vector, because '0' and '1' can't be std_logic_vector literals. It can be an array of character, as defined. But if '0' and '1' are the only values, an array of std_logic would be the obvious solution.

type hmatrix_array is array(0 to 3, 0 to 7) of std_logic;
constant mem:hmatrix_array:=("01011001","11100100","00100111","10011010");

Of course it's also a 1D array of std_logic_vector.

type hmatrix_array is array(0 to 3) of std_logic_vector(7 downto 0);

 

[ammassk]

but i dont want to access the whole 8 bits at a time. In my code i actually meant each each bit vector is a row and i need to access each bit in a row. It is working in my simulation model. But not synthesizable. Can you please tell me how to access each bit at a time. What I am trying to do is to find out column and row number of the element '1' in the matrix. That is why i used two dimensional array representation. Here, How can I enter my values accordingly?

 

[FvM]

std_logic_vector elements are individually accessable. The first point is that you don't need characters, just bits (or std_logic type) to represent '0' and '1' values.

I don't understand what's the problem with synthesizing. Characters are synthesizable as well, if you actually need it. I assume a problem of syntax errors.

You didn't yet ask a clear question nor reported a specific error message.