can I have unconstrained String as record element?

T

Tricky

Guest
Can I do what I asked, I suspect not, so Im thinking along the lines:

type my_record_type is
record
name : string(1 to 20);
....
end record my_record;

Basically, I want to be able to give the record name a constant string
when it is delcared like:

CONSTANT my_record : my_record_type := ( name => "Betty Swollocks",
--length only 15, complains unless I pad to 20 chars.
.......)

Or am I just going to have to pad the name with whitespace to make it
up to name'length?
 
On Jun 24, 11:48 am, Tricky <Trickyh...@gmail.com> wrote:
Can I do what I asked, I suspect not, so Im thinking along the lines:
Click to expand...
You suspect correctly, you can not have an unconstrained vector of any
type as a record element.

Basically, I want to be able to give the record name a constant string
when it is delcared like:

CONSTANT my_record : my_record_type := ( name => "Betty Swollocks",
--length only 15, complains unless I pad to 20 chars.
                                                                      .......)

Or am I just going to have to pad the name with whitespace to make it
up to name'length?
Click to expand...
A cleaner way than simply typing in the extra whitespace is to define
a function that pads on the appropriate spaces and put that in the
same package where 'my_type' is defined.

function Padder(s: string) return string is
variable s0: string(1 to s'length) := s;
variable RetVal: string(my_record_type.name'range);
begin
RetVal := (others => ' ');
RetVal(s0'range) := s0;
...
end function Padder;

That way you can initialize constants like this...
CONSTANT my_record : my_record_type := ( name => Padder("Betty
Swollocks"),...

KJ
 
On Jun 24, 11:48 am, Tricky <Trickyh...@gmail.com> wrote:
Can I do what I asked, I suspect not, so Im thinking along the lines:

type my_record_type is
  record
    name    : string(1 to 20);
    ....
  end record my_record;

Basically, I want to be able to give the record name a constant string
when it is delcared like:

CONSTANT my_record : my_record_type := ( name => "Betty Swollocks",
--length only 15, complains unless I pad to 20 chars.
                                                                      .......)

Or am I just going to have to pad the name with whitespace to make it
up to name'length?
Click to expand...
If you want variable length strings you can use an access type to
define a string pointer.

eg: type string_ptr is access string;

Your record would look something like this:

type my_record_type is
record
name : string_ptr;
....
end record my_record;

To set the string you use the "new" keyword to allocate memory.

my_record.name <= new string'("Betty Swollocks");

When you are done using my_record.name, you deallocate the memory
using the deallocate procedure.

Read up on access types.
 
On Jun 24, 1:27 pm, Andrew <sharp...@gmail.com> wrote:
On Jun 24, 11:48 am, Tricky <Trickyh...@gmail.com> wrote:





Can I do what I asked, I suspect not, so Im thinking along the lines:

type my_record_type is
  record
    name    : string(1 to 20);
    ....
  end record my_record;

Basically, I want to be able to give the record name a constant string
when it is delcared like:

CONSTANT my_record : my_record_type := ( name => "Betty Swollocks",
--length only 15, complains unless I pad to 20 chars.
                                                                      ........)

Or am I just going to have to pad the name with whitespace to make it
up to name'length?

If you want variable length strings you can use an access type to
define a string pointer.

eg: type string_ptr is access string;

Your record would look something like this:

type my_record_type is
  record
    name    : string_ptr;
    ....
  end record my_record;

To set the string you use the "new" keyword to allocate memory.

my_record.name <= new string'("Betty Swollocks");

When you are done using my_record.name, you deallocate the memory
using the deallocate procedure.

Read up on access types.- Hide quoted text -

- Show quoted text -
Click to expand...
Can a record containing access types be an entity port?
 
On Jun 24, 7:07 pm, Reuven <rpaley...@gmail.com> wrote:
On Jun 24, 1:27 pm, Andrew <sharp...@gmail.com> wrote:



On Jun 24, 11:48 am, Tricky <Trickyh...@gmail.com> wrote:

Can I do what I asked, I suspect not, so Im thinking along the lines:

type my_record_type is
  record
    name    : string(1 to 20);
    ....
  end record my_record;

Basically, I want to be able to give the record name a constant string
when it is delcared like:

CONSTANT my_record : my_record_type := ( name => "Betty Swollocks",
--length only 15, complains unless I pad to 20 chars.
                                                                      ........)

Or am I just going to have to pad the name with whitespace to make it
up to name'length?

If you want variable length strings you can use an access type to
define a string pointer.

eg: type string_ptr is access string;

Your record would look something like this:

type my_record_type is
  record
    name    : string_ptr;
    ....
  end record my_record;

To set the string you use the "new" keyword to allocate memory.

my_record.name <= new string'("Betty Swollocks");

When you are done using my_record.name, you deallocate the memory
using the deallocate procedure.

Read up on access types.- Hide quoted text -

- Show quoted text -

Can a record containing access types be an entity port?
Click to expand...
I don't think so... Signals and constants can't be declared as access
types. Access types are not synthesizable but they are incredibly
useful for testbenches.
 
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