[Icc-avr] Calculations

[Johan H. Bodin]

Bengt,

0 - 1 = -1 = 0xFFFF in 16-bit two-complements notation. 65535 if printed 
as an unsigned int/short.

Bengt Ragnemalm skrev:
> Hi!
> 
>  
> 
> I have spent some of my spare time during Christmas solving some strange 
> problems I have had with a design. My problems was something completely 
> different but I ended up with this:
> 
>  
> 
> - I have found a calculation that may be a compiler error.
> 
>  
> 
> This is my test code, baudrate is 38400:
> 
>  
> 
> #define F_CPU 7372800
> 
> 
> temp2 = F_CPU/(16L*baudrate)-1;    // Normal calculation, result OK
> temp2 = 0/(16L*baudrate)-1;    // Results into 65535
> 
> I guess that the last calculation error is because of some rounding 
> problem but obviously the correct answer is 0.
> 
>  
> 
> /Bengt
> 
> ________________________________________________________________
> 
> Bengt Ragnemalm                        Tel +46 13 22 24 97
> 
> Research engineer                                       FAX: +46 13 10 19 02
> 
> Linköpings Universitet                                
> mailto:bengt.ragnemalm at imt.liu.se
> 
> Inst. för Medicinsk Teknik Internet:        http://www.imt.liu.se 
> <http://www.imt.liu.se/>
> 
> S-581 85 Linköping SWEDEN
> 
>  
> 
>  
> 
> 
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