Re: [avr-gcc-list] Avoiding memory initialization

[Lai Kang Tin]

Hi,

I am sorry, it isn't working. You need not to modify anything, the simplest
way to do it:

 extern unsigned __bss_end;
 char *pointer = (char *)(&__bss_end + 1);
 
 void func()
 {
        *pointer = 0x12;
        *(pointer + 1) = 0x34;
        ...
 }

The storage between __bss_start and __bss_end is for all variables of you
application, and will be zero by C startup code of avr lib. After __bss_end
to the rest of RAM, it is free for you.

Cheers!

kang Tin LAI

On Fri, 19 Oct 2001, Lai Kang Tin wrote:

> Hi,
> 
> There is a loop inside the C startup code for zeroing the bss segment,
> to realize your requirement, you need to modify the C startup code
> for your own. The startup code uses symbol __bss_end to stop the zeroing loop,
> you change it to (__bss_end - 10), ten bytes assumed for your application.
> 
> To access these 10 bytes storage, use pointer in your codes:
> 
> extern unsigned __bss_end;
> char *pointer = (char *)(&__bss_end - 10);
> 
> void func()
> {
>       *pointer = 0x12;
> }
> 
> Cheers!
> 
> Kang Tin LAI
> 
> On Wed, 17 Oct 2001, [iso-8859-1] S S wrote:
> 
> > Hello Everybody,
> > 
> > I am using Atmega103. I have declared an array of char
> > which I do not wish to get initialized on every CPU
> > reset signal. I am keeping some acquired data here. In
> > short I want to use this array as battery backed up
> > RAM. However startup code clears the entire bss
> > section on every reset signal. Is there a way to avoid
> > this? Can somebody provide me source code to do the
> > same?
> > 
> > Thanks.
> > Sean.
> > 
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> 
> K.T.LAI
> address@hidden
> 
> 
> 
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K.T.LAI
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