Array at specific address

[Don]

Hi I have an array of unsigned chars, like:
MyArray[2048] = {0x00};

For memory-mapping purposes I need to store this array at a specific address
(0xFFFF1199)

How do I declare this?

I cant't do MyArray[2048] = {0x00} @ 0xFFFF1199 :-(

I am using the gnu compiler.

Best Regards
Don

[Joona I Palaste]

Re: Array at specific address

Don <nono@spam.dk > scribbled the following:[color=blue]
> Hi I have an array of unsigned chars, like:
> MyArray[2048] = {0x00};[/color]
[color=blue]
> For memory-mapping purposes I need to store this array at a specific address
> (0xFFFF1199)[/color]
[color=blue]
> How do I declare this?[/color]

You can't. Not under ISO standard C. On some implementations , you can't
declare it at all.
[color=blue]
> I cant't do MyArray[2048] = {0x00} @ 0xFFFF1199 :-([/color]

No, you can't.
[color=blue]
> I am using the gnu compiler.[/color]

It depends on more than your compiler. Some operating systems don't
allow specific addresses at all, due to security reasons. What happens
if some other process is already using that memory?
Please ask in gnu.gcc.help or a system-specific newsgroup.

--
/-- Joona Palaste (palaste@cc.hel sinki.fi) ---------------------------\
| Kingpriest of "The Flying Lemon Tree" G++ FR FW+ M- #108 D+ ADA N+++|
| http://www.helsinki.fi/~palaste W++ B OP+ |
\----------------------------------------- Finland rules! ------------/

[Derk Gwen]

Re: Array at specific address

"Don" <nono@spam.dk > wrote:
# Hi I have an array of unsigned chars, like:
# MyArray[2048] = {0x00};

If it _has_ to be an array instead of (unsigned char*), many linkers allow you to
specify the address of extern objects. You might try checking what your linker
permits.

--
Derk Gwen http://derkgwen.250free.com/html/index.html
You face forward, or you face the possibility of shock and damage.

[Kevin Easton]

Re: Array at specific address

Derk Gwen <derkgwen@hotpo p.com> wrote:[color=blue]
> "Don" <nono@spam.dk > wrote:
> # Hi I have an array of unsigned chars, like:
> # MyArray[2048] = {0x00};
>
> If it _has_ to be an array instead of (unsigned char*), many linkers allow you to
> specify the address of extern objects. You might try checking what your linker
> permits.[/color]

You can do it without linker magic also:

#define MyArray (*(volatile unsigned char (*)[2048])(0xdeadbeef))

- Kevin.

[Darrell Grainger]

Re: Array at specific address

On Thu, 25 Sep 2003, Don wrote:
[color=blue]
> Hi I have an array of unsigned chars, like:
> MyArray[2048] = {0x00};
>
> For memory-mapping purposes I need to store this array at a specific address
> (0xFFFF1199)
>
> How do I declare this?
>
> I cant't do MyArray[2048] = {0x00} @ 0xFFFF1199 :-(
>
> I am using the gnu compiler.[/color]

If possible, just use:

unsigned char *MyArray = (unsigned char *)0xFFFF1199;

and then use MyArray as if you declared it as an array. The only
difference is that sizeof(MyArray) will not return 2048.

If you have to have it as an array then check with a newsgroup that deals
with your compiler. You can sometimes define a section of data to a linker
section name (.text, .bss. data, etc.) and then instruct the linker to put
that section at a specific memory location. This is highly dependent on
your linker and completely off topic for comp.lang.c.

--
darrell at cs dot toronto dot edu
or
main(){int j=1234;char t[]=":@abcdefghijk lmnopqrstuvwxyz .\n",*i=
"iqgbgxmdbjlgdv .lksrqek.n";cha r *strchr(const char *,int);while(
*i){j+=strchr(t ,*i++)-t;j%=sizeof t-1;putchar(t[j]);} return 0;}

[Mark McIntyre]

Re: Array at specific address

On Thu, 25 Sep 2003 10:02:07 GMT, in comp.lang.c , Kevin Easton
<kevin@-nospam-pcug.org.au> wrote:
[color=blue]
>Derk Gwen <derkgwen@hotpo p.com> wrote:[color=green]
>> "Don" <nono@spam.dk > wrote:
>> # Hi I have an array of unsigned chars, like:
>> # MyArray[2048] = {0x00};
>>
>> If it _has_ to be an array instead of (unsigned char*), many linkers allow you to
>> specify the address of extern objects. You might try checking what your linker
>> permits.[/color]
>
>You can do it without linker magic also:
>
>#define MyArray (*(volatile unsigned char (*)[2048])(0xdeadbeef))[/color]

When I tried this on my DS9K, it said "moo" and printed out a recipe
for making cow from hamburger.


--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.angelfire.c om/ms3/bchambless0/welcome_to_clc. html>

[Martijn]

Re: Array at specific address

>> #define MyArray (*(volatile unsigned char (*)[2048])(0xdeadbeef))[color=blue]
>
> When I tried this on my DS9K, it said "moo" and printed out a recipe
> for making cow from hamburger.[/color]

liar

[Micah Cowan]

Re: Array at specific address

Joona I Palaste <palaste@cc.hel sinki.fi> writes:
[color=blue]
> Don <nono@spam.dk > scribbled the following:[color=green]
> > Hi I have an array of unsigned chars, like:
> > MyArray[2048] = {0x00};[/color]
>[color=green]
> > For memory-mapping purposes I need to store this array at a specific address
> > (0xFFFF1199)[/color]
>[color=green]
> > How do I declare this?[/color]
>
> You can't. Not under ISO standard C. On some implementations , you can't
> declare it at all.[/color]

Of course you can.

memcpy((void*)0 xFFFF1199, MyArray, sizeof MyArray);

Now, whether or not this does what you want is
implementation-defined, but you certainly can do it, if it's
doable. The Standard specifically says so.

-Micah

[Default User]

Re: Array at specific address

Martijn wrote:[color=blue]
>[color=green][color=darkred]
> >> #define MyArray (*(volatile unsigned char (*)[2048])(0xdeadbeef))[/color]
> >
> > When I tried this on my DS9K, it said "moo" and printed out a recipe
> > for making cow from hamburger.[/color]
>
> liar[/color]


It would be just like the DS9000 to print out a bogus recipe. That's the
kind of thing it likes to do.




Brian Rodenborn

[Micah Cowan]

Re: Array at specific address

Default User <first.last@com pany.com> writes:
[color=blue]
> Martijn wrote:[color=green]
> >[color=darkred]
> > >> #define MyArray (*(volatile unsigned char (*)[2048])(0xdeadbeef))
> > >
> > > When I tried this on my DS9K, it said "moo" and printed out a recipe
> > > for making cow from hamburger.[/color]
> >
> > liar[/color]
>
>
> It would be just like the DS9000 to print out a bogus recipe. That's the
> kind of thing it likes to do.
>[/color]

Should be thankful it didn't launch nukes

http://dspace.dial.pipex.com/town/green/gfd34/art/

-Micah

[Jack Klein]

Re: Array at specific address

On 25 Sep 2003 15:33:28 -0700, Micah Cowan <micah@cowan.na me> wrote in
comp.lang.c:
[color=blue]
> Joona I Palaste <palaste@cc.hel sinki.fi> writes:
>[color=green]
> > Don <nono@spam.dk > scribbled the following:[color=darkred]
> > > Hi I have an array of unsigned chars, like:
> > > MyArray[2048] = {0x00};[/color]
> >[color=darkred]
> > > For memory-mapping purposes I need to store this array at a specific address
> > > (0xFFFF1199)[/color]
> >[color=darkred]
> > > How do I declare this?[/color]
> >
> > You can't. Not under ISO standard C. On some implementations , you can't
> > declare it at all.[/color]
>
> Of course you can.
>
> memcpy((void*)0 xFFFF1199, MyArray, sizeof MyArray);
>
> Now, whether or not this does what you want is
> implementation-defined, but you certainly can do it, if it's
> doable. The Standard specifically says so.
>
> -Micah[/color]

Exactly how does this declare an array of 2048 unsigned characters at
all?

BTW, you're another one who could use a proper signature separator.

--
Jack Klein
Home: http://JK-Technology.Com
FAQs for
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alt.comp.lang.l earn.c-c++ ftp://snurse-l.org/pub/acllc-c++/faq

[James]

Re: Array at specific address

Hi,

To declare an array in C:
{
char temp[100] ;

}

Compiler must know its size. If the array is declared in a context the
compiler places it in stack and if a global it places it in heap.



Now how to place an array at a specified location.

I think a static array u can't place it.


With a pointer u can do it.

char * p = (char *) 1000 ;


Now u can use p like u use an array.

p [10] works



Hope this helps,



Regards,
James

[Kevin Easton]

Re: Array at specific address

Mark McIntyre <markmcintyre@s pamcop.net> wrote:[color=blue]
> On Thu, 25 Sep 2003 10:02:07 GMT, in comp.lang.c , Kevin Easton
> <kevin@-nospam-pcug.org.au> wrote:
>[color=green]
>>Derk Gwen <derkgwen@hotpo p.com> wrote:[color=darkred]
>>> "Don" <nono@spam.dk > wrote:
>>> # Hi I have an array of unsigned chars, like:
>>> # MyArray[2048] = {0x00};
>>>
>>> If it _has_ to be an array instead of (unsigned char*), many linkers allow you to
>>> specify the address of extern objects. You might try checking what your linker
>>> permits.[/color]
>>
>>You can do it without linker magic also:
>>
>>#define MyArray (*(volatile unsigned char (*)[2048])(0xdeadbeef))[/color]
>
> When I tried this on my DS9K, it said "moo" and printed out a recipe
> for making cow from hamburger.[/color]

A legal preprocessor directive did all that? I think you need to get a
conforming implementation (I'm reliably informed that one exists for the
DS9000).

- Kevin.

[Mark McIntyre]

Re: Array at specific address

On Fri, 26 Sep 2003 00:00:56 +0200, in comp.lang.c , "Martijn"
<subscription-NOSPAM-101@hotNOFILTER mail.com> wrote:
[color=blue][color=green][color=darkred]
>>> #define MyArray (*(volatile unsigned char (*)[2048])(0xdeadbeef))[/color]
>>
>> When I tried this on my DS9K, it said "moo" and printed out a recipe
>> for making cow from hamburger.[/color]
>
>liar[/color]

No, thats a greek musical instrument, beloved by muses the world over.
I do admit its often strung with cowgut though.

--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.angelfire.c om/ms3/bchambless0/welcome_to_clc. html>

[Mark McIntyre]

Re: Array at specific address

On Fri, 26 Sep 2003 10:32:04 GMT, in comp.lang.c , Kevin Easton
<kevin@-nospam-pcug.org.au> wrote:
[color=blue]
>Mark McIntyre <markmcintyre@s pamcop.net> wrote:[color=green]
>> On Thu, 25 Sep 2003 10:02:07 GMT, in comp.lang.c , Kevin Easton[color=darkred]
>>>
>>>#define MyArray (*(volatile unsigned char (*)[2048])(0xdeadbeef))[/color]
>>
>> When I tried this on my DS9K, it said "moo" and printed out a recipe
>> for making cow from hamburger.[/color]
>
>A legal preprocessor directive did all that?[/color]

The message appeared at runtime. The result of the directive is just a
tad implementation defined, I believe.
[color=blue]
>I think you need to get a
>conforming implementation (I'm reliably informed that one exists for the
>DS9000).[/color]

The one I have is as conforming as it gets, if somewhat
pathological...


--
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.angelfire.c om/ms3/bchambless0/welcome_to_clc. html>