Re: [avr-gcc-list] Calling function with hard coded address

[Simon Han]

To reply my own question.  :-)

The problem is that gcc does sign extension to the value.
Changing to value less than 0x7fe fixed the problem.

Simon

On Oct 31, 2006, at 9:30 PM, Simon Han wrote:

> Hi all,
>
>         I am trying to call functions with hard coded address as follow.
>
> typedef void (*func_type)( void );
>
> ((func_type) 0x1D400)();
>
> The problem is that the generated code is slightly different...  
> (shown below)
>
> ff 95 00 ea     call    0x7fd400
>
> Compare to standard function call (shown below)
>
> 0e 94 00 ea   call   0x1d400
>
> What happened was that the upper 8 bits (bit16 to bit23 of address  
> bits) are set to 1's instead of 0's.
>
> My questions are following.
>
> 1. Is this a bug?
>
> 2. is there a way to get around this?
>
> I am using avr-gcc 3.4.3 and binutil 2.15.
>
> Thank you for any suggestion,
> Simon
>
>
>
>
>
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