Feeling kind of stupid about pointers

[PullnOutHair]

I know that I should know how to do this, but for some reason it is
escapeing me right now and I was hoping someone here could help. I
need to setup a pointer to the memory location 0x30000000. I am
working on a linux system that has hardware inputs remapped to that
address and I have to read them. I am just drawing a blank on how to
actually assign the address of a pointer to point to.

[red floyd]

PullnOutHair wrote:

I know that I should know how to do this, but for some reason it is
escapeing me right now and I was hoping someone here could help. I
need to setup a pointer to the memory location 0x30000000. I am
working on a linux system that has hardware inputs remapped to that
address and I have to read them. I am just drawing a blank on how to
actually assign the address of a pointer to point to.

You don't do it in userland. That said.
assert(sizeof(void*) >= sizeof(unsigned long))
void* ptr = reinterpret_cast<void*>(0x30000000UL);

[PullnOutHair]

red floyd <no*****@here.dude> wrote in message news:<ID****************@newssvr27.news.prodigy.co m>...

You don't do it in userland. That said.
What do you mean?

assert(sizeof(void*) >= sizeof(unsigned long))
void* ptr = reinterpret_cast<void*>(0x30000000UL);

[Jonathan Turkanis]

"PullnOutHair" <di*********@hotmail.com> wrote in message
news:ca**************************@posting.google.c om...

red floyd <no*****@here.dude> wrote in message news:<ID****************@newssvr27.news.prodigy.co m>...

You don't do it in userland. That said.

What do you mean?

http://info.astrian.net/jargon/terms/u/userland.html

Jonathan

[Ioannis Vranos]

PullnOutHair wrote:

I know that I should know how to do this, but for some reason it is
escapeing me right now and I was hoping someone here could help. I
need to setup a pointer to the memory location 0x30000000. I am
working on a linux system that has hardware inputs remapped to that
address and I have to read them. I am just drawing a blank on how to
actually assign the address of a pointer to point to.

Assuming that the platform will allow you, and assuming the pointer is
of type whatever, you can do:

whatever *p = reinterpret_cast<whatever *>(0x30000000);


Regards,

Ioannis Vranos

http://www23.brinkster.com/noicys

[JKop]

Ioannis Vranos posted:

PullnOutHair wrote:

I know that I should know how to do this, but for some reason it is escapeing me right now and I was hoping someone here could help. I need to setup a pointer to the memory location 0x30000000. I am working on a linux system that has hardware inputs remapped to that address and I have to read them. I am just drawing a blank on how to actually assign the address of a pointer to point to.
Assuming that the platform will allow you, and assuming

the pointer is of type whatever, you can do:

whatever *p = reinterpret_cast<whatever *>(0x30000000);


Regards,

Ioannis Vranos

http://www23.brinkster.com/noicys

Should the "volatile" keyword be in there at all?

-JKop

[red floyd]

JKop wrote:

Ioannis Vranos posted:

whatever *p = reinterpret_cast<whatever *>(0x30000000);

Should the "volatile" keyword be in there at all?

-JKop

Depends on whether it's data that can change out from underneath him.

My favorite variant of this (embedded system, C, not C++) was:

const volatile unsigned long * const PREGISTER =
(const volatile unsigned long *) 0xC0000000L;

It was a read-only memory mapped register.

[Ioannis Vranos]

JKop wrote:

whatever *p = reinterpret_cast<whatever *>(0x30000000);

Should the "volatile" keyword be in there at all?

volatile is used when the value of the variable can change between reads
outside of the program (e.g. an external thermometer). It has as a
result the compiler to not perform some optimisations.


Regards,

Ioannis Vranos

http://www23.brinkster.com/noicys