Dividing array in parts.

Altera_Forum · ‎08-29-2011

Hi, I'm having a problem when I try to take just one part of an array, for example:

I have a 512x512 array, and want just the first 8x8 samples.

I'm having the following error:

"slice of object cannot be specified for object that has an array type of more than one dimension"

Here's part of the code:

Type array_t IS ARRAY (0 to 7, 0 to 7) OF STD_LOGIC_VECTOR(0 to 7);

Type array_t2 IS ARRAY (0 to 511, 0 to 511) OF STD_LOGIC_VECTOR(0 to 7);

SIGNAL input: array_t

SIGNAL output: array_t2

input<=output(0 to 7, 0 to 7);

Thank you!!

Altera_Forum · ‎08-29-2011

you cannot do that with a 2d array, you can only access one entry at a time.

for this, you would need a loop (ps. I think you means to assign output, not input!)


for i in input'range(1) loop
  for j in input'range(2) loop
    output(i,j) <= input(i,j);
  end loop;
end loop;

Altera_Forum · ‎08-29-2011

Thanks Tricky. You are always saving my life.

As soon as possible I will teste and reply.

Thanks again!

Altera_Forum · ‎08-30-2011

--- Quote Start ---

you cannot do that with a 2d array, you can only access one entry at a time.

--- Quote End ---

Respectively a row slice at once. Keep in mind, that a 2D array isn't but a mapping scheme to represent data structures, that are 1D arrays by nature.

Altera_Forum · ‎08-31-2011

It didn't worked, I get an error:

"indexed name returns a value whose type does not match "array_t", the type of the target expression."

Type array_t IS ARRAY (0 to 7, 0 to 7) OF STD_LOGIC_VECTOR(0 to 7);

Type array_t2 IS ARRAY (0 to 511, 0 to 511) OF STD_LOGIC_VECTOR(0 to 7);

SIGNAL output: array_t

SIGNAL input: array_t2

process(clk)

begin

for i in 0 to 7 loop

for j in 0 to 7 loop

output<=input(i, j);

end loop;

end process;

Thank You!

Altera_Forum · ‎08-31-2011

you need to change it to

output(i, j) <= input(i,j);

Altera_Forum · ‎08-31-2011

Oh...Ok,

Thanks!

Altera_Forum · ‎09-05-2011

The code worked fine if I want to do something using the same index:

output(0, 0) <= input(0, 0);

but how about

output(0, 0) <= input(8, 8);

output(0, 1) <= input(8, 9);

How can be done that?

Thank You!

Altera_Forum · ‎09-05-2011

I have tried this before and didn't worked. But the error was somewhere else.

This works.

output(i, j) <= input(i, j+8);