Re: Error --unconstrained record or array type is not supported
Alan Fitch
> I was trying to compile the VHDL code with generic (Width:positive:=
> 8);
>
> In Quartus, I got the following error.
> Error (10427): VHDL aggregate error at GCD.vhd(49): OTHERS choice used
> in aggregate for unconstrained record or array type is not supported
<snip>
> -----------------------------------------------------------------
> library IEEE;
> use IEEE.STD_Logic_1164.all, IEEE.Numeric_STD.all;
> entity GCD is
> generic (Width:positive:= 8); ---I have also tried natural and
> integer, but all failed.
> port (Clock,Reset,Load: in std_logic;
> A,B: in unsigned(Width-1 downto 0);
> Done: out std_logic;
> Y: out unsigned(Width-1 downto 0));
> end entity GCD;
> architecture RTL of GCD is
> signal A_New,A_Hold,B_Hold: unsigned(Width-1 downto 0);
> signal A_lessthan_B: std_logic;
> begin
<snip>
> if (B_Hold = (others => '0')) then -- here is the error B_Hold =
> (others => '0')
> -------------------------------------------------------------------------------
> I also googled some topic about it, is it true that when using
> generics, B_Hold = (others => '0') OTHERS choice used in aggregate for
> unconstrained record or array type is not supported?
Yes it's true. The expression (others => '0') doesn't hold enough type
information to make the compiler happy.
There are various ways round this:
1. use a subtype, e.g.
subtype vecT is unsigned (width -1 downto 0);
...
if B_hold = VecT'(others => '0')
2. The other way is to use the aggregate itself by naming the aggregate
choices, e.g.
if B_hold = (Width -1 downto 0 => '0') then
I haven't tried these in Quartus,
regards
Alan
--
Alan Fitch
Doulos
http://www.doulos.com
Brian Drummond
<Zhey...@googlemail.com> wrote:
>I was trying to compile the VHDL code with generic (Width:positive:=
>8);
>
>In Quartus, I got the following error.
>Error (10427): VHDL aggregate error at GCD.vhd(49): OTHERS choice used
>in aggregate for unconstrained record or array type is not supported
> if (B_Hold = (others => '0')) then
-- here is the error
It is an error because you can overload "=" with an "=" operator which works on
different size operands (typically returning false if different size).
Therefore the parser cannot possibly know how many "others" there are.
The solution is to make the RHS operand explicitly the same size as the LHS
operand, whatever that size is.
One reliable way is simply
if (B_Hold = (B_Hold'range => '0')) then
- Brian
JimLewis
Since B_hold is unsigned, you can take advantage of the overloading
and compare to an integer:
if B_hold = 0 then
Cheers,
Jim
SynthWorks VHDL Training
http://www.synthworks.com