Re: How to control code segments ?

[Dong Phuong <dongphuong2410 at yahoo dot com>]

"Linker relaxation" is maybe what I'm looking for. 

But I've searched it on google , but there are few
doccuments about it, now I haven't imagined yet how to
implement Linker Relaxation. 

Could you tell me some of doccuments about it and
where in the binutils that it was implemented ? 

--- Alan Lehotsky <qsmgmt@earthlink.net> wrote:

> Look at the implementation of the IP2K compiler and
> linker.
> It uses a segmented paged architecture just like the
> machine you are  
> describing.
> 
> In essence what we did was implement linker
> relaxation to deal with  
> this.
> When we called any function, we emitted the
> appropriate long-call by  
> setting
> the page register and jumping to the location on
> that page.
> 
> In the linker, we implemented relaxation code that
> looked to see if
> we were changing to the SAME page, and if so deleted
> the instruction  
> changing
> the PAGE and did a local jump to the destination. 
> Now, because a  
> function could cross a page
> boundary (we only had 4kb pages (and 16 bit
> instructions), all our  
> branches were done this way
> (if I recall correctly).
> 
> It's a little tedious, but not too technically
> demanding a solution....
> 
> Al Lehotsky
> 
> On Nov 30, 2008, at 2:06 PM, Dong Phuong wrote:
> 
> > I'm porting for a microcontroler which has
> segmented
> > memory.
> >
> > THe memory is devided into many pages, each page
> is
> > 16K. And I'm going to use 256 pages for code. But
> > these 256 pages are not continuous in physical
> memory,
> > so when I want to jump to a function, I have to
> know
> > what is the segment address of this function, and
> then
> > set the CSP with this value, and jump to it.
> >
> > So what I want to know is if I'm in a function, is
> > there any way for me to know what code segments
> I'm
> > locating in ? If I know this,  when I have to jump
> to
> > another function, I can decide wheather this
> function
> > is in the same segment with the function that I'm
> > locating in, and then can decide if I have to
> change
> > the CSP.
> >
> > And when I compile a long long program with so
> many
> > methods, is there any way for GCC so that it can
> > realize that the code has exceeded 16K and have to
> use
> > a new segments ? or the user must explicit declare
> > this in the C source program ?
> >
> > If you know any hints or any doccument about this,
> > please show me. THank you very much.
> >
> >
> >
> 
>