ColdFire/68K Microcontrollers and ProcessorsのトピックRe: storage variable in the specific location in memory

storage variable in the specific location in memory

VeronicaFNX — Thu, 15 Mar 2007 15:09:59 GMT

Hello,
how I can storage variable in the specific location in memory?
For example I have

char variable; //I want have variable on address 0x2000 1500

but how it say to compiler?
I'm using Code warrior 6.3 and m52233demo
please help.
Regards
Vero

Re: storage variable in the specific location in memory

SimonMarsden_de — Thu, 15 Mar 2007 15:56:46 GMT

Hi Vero

You can use the Linker Control File (LCF) to do this. Have a look at the following thread, where a similar question was discussed:

http://forums.freescale.com/freescale/board/message?board.id=CFCOMM&message.id=1578#M1578

In particular, the second and third posts in this thread gives some details which might be helpful.

Good luck

Simon

Re: storage variable in the specific location in memory

mccPaul — Thu, 15 Mar 2007 15:59:42 GMT

Hi Vero,

If you declare an automatic variable in a function it will be created somewhere on the heap, if it is a static variable, it will be in the bss section of your linked binary. In both cases there is no way in C to make the compiler create a variable at a specific location.

What you can do is create a pointer variable and set that to point to the location you wish to use:

Code:

char *p_variable;p_variable = 0x20001500;// Now you just dereference the pointer to access your char// e.g. to set the variable to *:*p_variable = '*';

It is a good idea to declare this type of variable in your linker command file, along with your other memory map declarations in the way that Simon has pointed out.

Cheers,

Paul.

Message Edited by mccp on 2007-03-1510:02 AM

Message Edited by mccp on 2007-03-1510:03 AM