Lpc2000

I too gave a suspicious look at the startup code. But the thing is, 
in order to copy the modifiable data to RAM it must be in the ROM in 
the first place! It doesn't show in the lst file, whilst puts() 
parameters do.

I tried giving a const to the function's declaration, with no luck. 
However, I narrowed down the problem to auto-inlining: if I move the 
do_something() function to another source (I was testing with an 
empty body on the function!), the strings do show in the .data. This 
kinda makes sense, since the compiler realized that there was no 
point for that constant to be in the code in the first place. What do 
not makes much sense (but works well somehow) is:

char   d[20];
char* c = "AAAAAAAAAAAAAAAAA";

d[0] = *(c++);
d[1] = *(c++);
d[2] = *(c++);
d[3] = *(c++);

Here there's some weird optimization choices: instead of storing a 
number of A's and copying them without hesitation, the compiler 
*knows* they're all A's, so it loads an A in r2 and repeats it along d
[n]... :P If I change "AAAAAAA..." for "ABCDEF....".... it changes an 
A in r2, a D in r3, stores them in d[0],d[3], then performs ADD r2, 
r2, #2 and SUB r3, r3, #2 and stores r2 and r3 in d[1], d[2]. 
WTF!!!!!!!

OK, then it works. Oddly, but works. It's my fault for making so 
small test cases.

Guille


--- In lpc2000@yahoogroups.com, Robert Adsett <subscriptions@a...> 
wrote:
>
> At 11:08 PM 10/17/05 +0000, Guillermo Prandi wrote:
> >Hi! Has anybody found this? I'm using gcc 4.01 (latest WinARM) and 
I'm
> >compiling for LPC2138 (ARM7). If I use this kind of stuff, 
constants
> >don't get to the HEX file:
> 
> It sounds like a problem with your startup code.
> 
> 
> >char *c = "Hello";
> 
> 
> This string, for instance needs to be copied to RAM since your 
declaration 
> indicates it's modifiable.
> 
> 
> >or
> >
> >my_func("Hello");
> 
> 
> As will this if my_func is prototyped as void my_func (char *)
> I think that's the case.
> 
> 
> >However, if I use a built-in function like printf or puts, they 
do!:
> >
> >printf("Hello");
> 
> 
> This however can point to the string in flash since printf expects 
a const 
> string.
> 
> The prototype is something like
> 
> int printf( const char *, ...);
> 
> 
> Question:  Does the problem disappear if you declare the first case 
as
> 
> const char *c = "Hello";
> 
> and prototype the function in the second as
> 
> void my_func( const char *);
> 
> 
> 
> 
> >This only happens with -On, where n != 0.
> 
> 
> I'd be really confident that was the problem, except I don't see 
how this 
> final statement fits in.
> 
> Still the const/non-const nature of the two cases cries out as 
being 
> critical.  Maybe you are writing over the strings in RAM?
> 
> Robert
> 
> " 'Freedom' has no meaning of itself.  There are always 
restrictions,   be 
> they legal, genetic, or physical.  If you don't believe me, try to 
chew a 
> radio signal. "  -- Kelvin Throop, III
> http://www.aeolusdevelopment.com/
>