AVR-Chat

Thanks for pointing me to the div functions.  I believe I will be 
always working with positive numbers, but I have not finalized that 
part of the work.  I will have to see how it evolves.  Right now I 
am getting up to speed on the use and programming of the ATmega128.  
Then get back into C (it is almost like riding a bike), then I will 
actually write the software.  It is actually pretty simple 
software.  I just have to be sure never to have the off-by-one 
error, and there are MANY MANY ways to get this error in complex 
timing and 

-Tony

--- In AVR-Chat@yahoogroups.com, "Paul Curtis" <plc@r...> wrote:
> Robert et al, 
> 
> > At 02:18 PM 4/22/05 +0000, arhodes19044 wrote:
> > >I see the modulo function for floats, but is there an 
> > integer version 
> > >of modulo?  I did not see that.
> > 
> > %
> 
> % is indeed the integer modulus (remainder after division) 
operator, but
> implementations are allowed to implement this using either 
symmertic or
> floored division.  This is only a problem if you use '%' with 
integer
> operands which could possibly be negative.  In that case, two C
> implementations could produce different results on the SAME 
processor.
> 
> In order to get a guaranteed-consistent remainder after division, 
the C
> library provides div, ldiv and (optionally) lldiv functions that 
have a

> DEFINED quotient and remainder that is the same for every C
> implementation irrespective of processor or underlying division
> opcode/algorithm.
> 
> Regards,
> 
> --
> Paul Curtis, Rowley Associates Ltd  http://www.rowley.co.uk
> CrossWorks for MSP430, ARM, AVR and (soon) MAXQ processors

Robert et al, 

> At 02:18 PM 4/22/05 +0000, arhodes19044 wrote:
> >I see the modulo function for floats, but is there an 
> integer version 
> >of modulo?  I did not see that.
> 
> %

% is indeed the integer modulus (remainder after division) operator, but
implementations are allowed to implement this using either symmertic or
floored division.  This is only a problem if you use '%' with integer
operands which could possibly be negative.  In that case, two C
implementations could produce different results on the SAME processor.

In order to get a guaranteed-consistent remainder after division, the C
library provides div, ldiv and (optionally) lldiv functions that have a
DEFINED quotient and remainder that is the same for every C
implementation irrespective of processor or underlying division
opcode/algorithm.

Regards,

--
Paul Curtis, Rowley Associates Ltd  http://www.rowley.co.uk
CrossWorks for MSP430, ARM, AVR and (soon) MAXQ processors