character to std_logic_vector

Greetings,

I recently tried to open some files for reading and I managed to read
characters and then putting them in hexadecimal format. ( I used HREAD
form ieee.std_textio ). My question is the following: is there anyway
for reading characters ( from 0-255 in ascii ) and then converting them
do a std_logic_vector or an integer.
For example if I have a "K" on the file the output would be "4B" since
its the hexadecimal code of the character "K".

Thanks in advance,

Pedro Claro

Pedro Claro

Hi Pedro!


> I recently tried to open some files for reading and I managed to read
> characters and then putting them in hexadecimal format.

I've posted a quick&very dirty solution some time ago:
http://groups.google.de/groups?q=Ral...ncis.de&rnum=2


Ralf

Ralf Hildebrandt

This works for me:

...
use ieee.std_logic_arith.all;
...
MyStdLogicVector <= CONV_STD_LOGIC_VECTOR(character'pos(MyChar),;
...

HTH

Francisco Camarero



Pedro Claro wrote:
>
> Greetings,
>
> I recently tried to open some files for reading and I managed to read
> characters and then putting them in hexadecimal format. ( I used HREAD
> form ieee.std_textio ). My question is the following: is there anyway
> for reading characters ( from 0-255 in ascii ) and then converting them
> do a std_logic_vector or an integer.
> For example if I have a "K" on the file the output would be "4B" since
> its the hexadecimal code of the character "K".
>
> Thanks in advance,
>
> Pedro Claro

Francisco Camarero

"Francisco Camarero" <> wrote in message
news:...
> This works for me:
> MyStdLogicVector <= CONV_STD_LOGIC_VECTOR(character'pos(MyChar),;

Fine for simulation. It doesn't work correctly in most synthesis tools,
sadly.
--

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Jonathan Bromley

I tried that. And it worked.
Thanks for the replies.

Pedro Claro


Francisco Camarero <> wrote in message news:<>...
> This works for me:
>
> ..
> use ieee.std_logic_arith.all;
> ..
> MyStdLogicVector <= CONV_STD_LOGIC_VECTOR(character'pos(MyChar),;
> ..
>
> HTH
>
> Francisco Camarero
>
>
>
> Pedro Claro wrote:
> >
> > Greetings,
> >
> > I recently tried to open some files for reading and I managed to read
> > characters and then putting them in hexadecimal format. ( I used HREAD
> > form ieee.std_textio ). My question is the following: is there anyway
> > for reading characters ( from 0-255 in ascii ) and then converting them
> > do a std_logic_vector or an integer.
> > For example if I have a "K" on the file the output would be "4B" since
> > its the hexadecimal code of the character "K".
> >
> > Thanks in advance,
> >
> > Pedro Claro

Pedro Claro

Jonathan Bromley wrote:
>
> "Francisco Camarero" <> wrote in message
> news:...
> > This works for me:
> > MyStdLogicVector <= CONV_STD_LOGIC_VECTOR(character'pos(MyChar),;
>
> Fine for simulation. It doesn't work correctly in most synthesis tools,
> sadly.


I know.

I could assume from Pedro's message that,
if he was opening some files for reading,
he was not trying to synthesize that code.

Fran.



Pedro Claro wrote:
>
> Greetings,
>
> I recently tried to open some files for reading and I managed to read
> characters and then putting them in hexadecimal format. ( I used HREAD
> form ieee.std_textio ).

Francisco Camarero

Amontec Team wrote:
>
> Pedro Claro wrote:
> > Greetings,
> >
> > I recently tried to open some files for reading and I managed to read
> > characters and then putting them in hexadecimal format. ( I used HREAD
> > form ieee.std_textio ). My question is the following: is there anyway
> > for reading characters ( from 0-255 in ascii ) and then converting them
> > do a std_logic_vector or an integer.
> > For example if I have a "K" on the file the output would be "4B" since
> > its the hexadecimal code of the character "K".
> >
> > Thanks in advance,
> >
> > Pedro Claro
> For synthesis, you have to write a big mux (using case) including all
> conversion (has a rom description).
>
> I wrote this conversion table before.

Excuse me if I don't understand the issue here.

Why would someone want to synthesize a 'character to std_logic_vector' function?

File handling is not synthesizable, and I don't think any synthesis could can
handle character types, can they?

Fran.

Francisco Camarero

[Ruudiculus]

Hi,

I also use character to std_logic_vector conversion, by means of a charToByte(charIn) function:

to_unsigned(character'pos(charIn),8);

During simulation I use this to insert characters from files, but I also need it for synthesis, since I have an entity that parses serial data that is in ASCII. For readability in my code it is nicer to do a compare like:

... if serialByteIn = charToByte('{') then ...

Instead of:

... if serialByteIn = X"7B" then ...

So I do find it useful for synthesis as well.

Ruudiculus