Altera's Megafunction altaccumulator

Hi,

It seems that it is not possible to instantiate an accumulator with the
Megawizard plug-in which has an input wider than 33 bits.

If you set the input wider than 33 bits it gives the following error:

---------------------------------------------------------------------------
Microsoft Visual C++ Runtime Library

Runtime Error!

Program: C:\altera\quartus41\bin\mega_altaccumulate.exe

This application has requested the Runtime to terminate it in an unusual
way,
Please contact the application's support team for more information.
----------------------------------------------------------------------------
--

I have winXP sp1 running QuartusII 4.1 sp2 full version.
I have tried this to other PCs with similar configuration and still did not
work.
Finally, I have read all help files with megawizard and the altaccumulate
and have not seen anywhere stating this limitation.

Thanks to anyone which can help.

Christos

It maybe due to the input types used,unsigned types wider than 32 bits
cannot be used without overflow errors occuring in conversion
functions.I am not sure that is the reason but its worth checking.

Christos wrote:
> Hi,
>
> It seems that it is not possible to instantiate an accumulator with
the
> Megawizard plug-in which has an input wider than 33 bits.
>
> If you set the input wider than 33 bits it gives the following error:
>
>
---------------------------------------------------------------------------
> Microsoft Visual C++ Runtime Library
>
> Runtime Error!
>
> Program: C:\altera\quartus41\bin\mega_altaccumulate.exe
>
> This application has requested the Runtime to terminate it in an
unusual
> way,
> Please contact the application's support team for more information.
>
----------------------------------------------------------------------------
> --
>
> I have winXP sp1 running QuartusII 4.1 sp2 full version.
> I have tried this to other PCs with similar configuration and still
did not
> work.
> Finally, I have read all help files with megawizard and the
altaccumulate
> and have not seen anywhere stating this limitation.
>
> Thanks to anyone which can help.
>

Hi Christos,

  We tested the altaccumulate megafunction with a size of 34 bits and
with all other settings as default, the problem mentioned was not
encountered. Would it be possible to email me the settings that were
chosen in the Megawizard that were no-default? That would help us
reproduce the problem.

- Subroto Datta
Altera Corp.

> Christos

Christos wrote:
> Hi,
>
> It seems that it is not possible to instantiate an accumulator with
the
> Megawizard plug-in which has an input wider than 33 bits.
>
> If you set the input wider than 33 bits it gives the following error:
>
>
---------------------------------------------------------------------------
> Microsoft Visual C++ Runtime Library
>
> Runtime Error!
>
> Program: C:\altera\quartus41\bin\mega_altaccumulate.exe
>
> This application has requested the Runtime to terminate it in an
unusual
> way,
> Please contact the application's support team for more information.
>
----------------------------------------------------------------------------
> --
>
> I have winXP sp1 running QuartusII 4.1 sp2 full version.
> I have tried this to other PCs with similar configuration and still
did not
> work.
> Finally, I have read all help files with megawizard and the
altaccumulate
> and have not seen anywhere stating this limitation.
>
> Thanks to anyone which can help.
>

Hi Christos,

  We tested the altaccumulate megafunction with a size of 34 bits and
with all other settings as default, the problem mentioned was not
encountered. Would it be possible to email me the settings that were
chosen in the Megawizard that were no-default? That would help us
reproduce the problem.

- Subroto Datta
Altera Corp.

> Christos

Hi Subroto,

Sorry for the delay,
look at the bottom.

"Subroto Datta" <sdatta@altera.com> wrote in message
news:1108160336.097087.219950@o13g2000cwo.googlegroups.com...
>
>
> Hi Christos,
>
>   We tested the altaccumulate megafunction with a size of 34 bits and
> with all other settings as default, the problem mentioned was not
> encountered. Would it be possible to email me the settings that were
> chosen in the Megawizard that were no-default? That would help us
> reproduce the problem.
>
> - Subroto Datta
> Altera Corp.
>

settings:
data input 35 bits
result output 36 bits
leave the rest as default and should give the error..

Now that I was trying to reproduce the error I found something else:

I opened the altaccumulate and produced one accumulator with all default
settings (8bit input/output etc..)
then I double-clicked the symbol and the megawizard opens again to change
settings.
then I ask for 33 input, 34 output and the rest as is.
When it finishes it asks to overwrite the old files, I click OK,
then gives:
"Symbol altaccumulate0 has changed? Do you want to update it?", I click
"yes"
"Selected symbol or block" I click "yes"
and now I get the strange message:
"Can't find the block symbol altaccumulate0 -- if the file exists it is not
located in the Altera-provided or user-defined libraries." , I click "ok"
the symbol does not get updated but if I double click and thus re-open the
megawizard of this symbol then I find my settings to have been updated.

--------------------------------

what I need for my design is an accumulator with:
- 35 bit signed number input
- 40 bit result
- clken

---------------------------------

thanks in advance,
Subroto, you can mail me directly if you need more info at:

christos dot zamantzas at cern dot ch