[MPlayer-dev-eng] [PATCH] Yet another batch of warning fixes :->

[Anders Johansson]

Hi,

> On Tuesday, 10 December 2002, Anders Johansson wrote:
> > Hi,
> > 
> > > Hi,
> > > 
> > > > > >  #define ADDQUE(xi,xq,in)\
> > > > > >    xq[xi]=xq[xi+L]=(*in);\
> > > > > > -  xi=(--xi)&(L-1);
> > > > > > +  xi=(xi-1)&(L-1);\
> > > > > > +  xi--;
> > > > > 
> > > > > why?
> > > > 
> > > > He's correct that something's wrong here. Read the comp.lang.c faq.
> > > > The result of an expression similar to x=--x; is undefined. I have no
> > > ah. you're right
> > > but then, that extra xi--; is unneeded and wrong
> > > 
> > > so, the right fix would be:
> > > -  xi=(--xi)&(L-1);
> > > +  xi=(xi-1)&(L-1);
> > > 
> > > IMHO, Anders should confirm.
> > 
> > It is the index for a circular buffer, the sulution Arpi suggests
> > should work fine, but I haven't got time to test it right now.
> 
> Then why was xi decreased if it's not needed? My code does exactly the same
> thing as the original one. I won't insist on my solution, though. My
> intention was to tell you something was wrong there, and I've succeeded. :->

I am sorry but your code:

> > > > > > +  xi=(xi-1)&(L-1);\
> > > > > > +  xi--;

does not do the same thing as:

> > > +  xi=(xi-1)&(L-1);

You have to observe that this is a macro, not a function, your code
would result in irregular indexing of the circular buffer.

//Anders