WARNING:Xst:795: Size of operands are different : result is

[Chao]

Hi, all.

I have written one entity which has generic definition like the
following:
(the purpose is that I can dynamically generate different components
which is determined by the CLKOUT_PHASE_SFT parameter.)

entity DCM is
generic
(
CLKOUT_PHASE_SFT : STRING := "LOW";
);

architecture STRUCT of DCM is
begin

Line002 VAR_MODE : if (CLKOUT_PHASE_SFT = "VARIABLE") generate
......

Line008 FIX_MODE : if (CLKOUT_PHASE_SFT = "FIXED") generate
......

end STRUCT;

but when I tried to implement it in ISE6.2 with parameter "FIXED", it
gave the following warning message: WARNING:Xst:795: at Line002, Size
of operands are different : result is <false>. My assumption is that
the string length is different, therefore ISE prints out the message.
Does anyone give me some hint how to solve it? Or is it harmless?

Thanks in advance.

Chao. (c.chen@gmx.de)

 

[Mike Treseler]

c.chen@gmx.de (Chao) wrote in message news:<8228a344.0406260707.225cf92a@posting.google.com>...

but when I tried to implement it in ISE6.2 with parameter "FIXED", it
gave the following warning message: WARNING:Xst:795: at Line002, Size
of operands are different : result is <false>. My assumption is that
the string length is different, therefore ISE prints out the message.

That's right. Consider:

"VAR"
"FIX"
"LOW"

or use integers.

Does anyone give me some hint how to solve it? Or is it harmless?

Not harmless.
Sim won't work and generates won't happen until
all the string lengths match the base entity.

-- Mike Treseler

 

[Just an Illusion]

Hi Chao,

Or use a type.

type FOO is ("VARIABLE", "FIXED", "LONG"...);

it is equivalent to Mike proposal about integers.

JaI

Mike Treseler wrote:

c.chen@gmx.de (Chao) wrote in message news:<8228a344.0406260707.225cf92a@posting.google.com>...



but when I tried to implement it in ISE6.2 with parameter "FIXED", it
gave the following warning message: WARNING:Xst:795: at Line002, Size
of operands are different : result is <false>. My assumption is that
the string length is different, therefore ISE prints out the message.



That's right. Consider:

"VAR"
"FIX"
"LOW"

or use integers.



Does anyone give me some hint how to solve it? Or is it harmless?



Not harmless.
Sim won't work and generates won't happen until
all the string lengths match the base entity.

-- Mike Treseler

 

[Chao]

thank you, you two guys.

Meanwhile I tried with your suggestion and want to give my comment to
that:
1. during the simulation, there was no problem at all.
2. during ISE implementation, it gave out ONLY the "warning": the size
is different. But the process was continuing to the end. (I assumed,
well, no problem in fact)
3. but when I downloaded to the HW, I could not get the multiplied
frequency at all. terrible experience. :-( It costed me several hours
to find out this. I hope this will help others to avoid my mistake.

Chao.

 

[Mike Treseler]

Just an Illusion <illusion_to_net@yahoo.fr> wrote in message news:<40E12835.5020807@yahoo.fr>...

Hi Chao,

Or use a type.

type FOO is ("VARIABLE", "FIXED", "LONG"...);

it is equivalent to Mike's proposal about integers.

The only difference is that types string and integer
are built-in. Type foo would need a package and USE clause.

-- Mike Treseler

 

[Just an Illusion]

Hi Mike,

Mike Treseler wrote:

Just an Illusion <illusion_to_net@yahoo.fr> wrote in message news:<40E12835.5020807@yahoo.fr>...


Hi Chao,

Or use a type.

type FOO is ("VARIABLE", "FIXED", "LONG"...);

it is equivalent to Mike's proposal about integers.



The only difference is that types string and integer
are built-in. Type foo would need a package and USE clause.


Not necessarily, because type can be defined into the

architecture_declarative_part
That limit is usage to the current architecture, but it can be enought.;-)

-- Mike Treseler


JaI

 

[Mike Treseler]

Just an Illusion wrote:

Not necessarily, because type can be defined into the
architecture_declarative_part
That limit is usage to the current architecture, but it can be enought.;-)

The OP was discussing an entity generic.

-- Mike Treseler