Re: [avr-gcc-list] can't compile simple test.c

[Gregory Berardi]

You're right.  I had seen that output and didn't realize it meant that
it was the stack pointer.  The original code used SP and I hadn't tried
another variable name, I thought it was very unconventional to use an
uppercase variable name.  IAR must not define SP as the stack pointer. 
Changing SP to sp fixed it.


Thanks for your help.


-greg



Outside of a dog, a book is a man's best friend. Inside of a dog it's
too dark to read. 

-Groucho Marx


 
On Sun, 2003-08-24 at 15:17, Christian Vogel wrote:
> Hi Gregory,
> 
> > If I add -E to the CFLAGS, as suggested by Joerg Wunsch so that I may
> > see the preprocessor output, the code compiles and I get no errors but
> > the linker doesn't recognize the file format of the object file.
> 
> Of course. Because the linker wants to link object files... and by using
> -E you are giving him C-Code :-)
> 
> So if you convert yout test.c to the preprocessor output-file (test.e)
> with this command:
> 
>       avr-gcc -g -Os -mmcu=atmega103 -I/usr/local/avr/include/ -E -o test.E 
> test.c
> 
> you will notice, that the line where the compiler complains:
> 
>       float foo(float SP);
> 
> was converted after the pre-processor did his work (look at test.E) to:
> 
>       float foo(float (*(volatile unsigned int *)((0x3D) + 0x20)));
> 
> this is, because SP is defined to be a macro for the stack pointer (which
> in avr's unified memory/register space is at address 0x3D+0x20!
> 
> If you rename all SP-variables to, for example, _SP, your code compiles!
> 
>       Chris