[FFmpeg-devel] [PATCH] AAC: type puns for 16 bit floating point rounding

[Uoti Urpala]

On Thu, 2008-12-04 at 03:13 +0000, M?ns Rullg?rd wrote:
> > @@ -838,24 +842,45 @@ static int decode_spectrum_and_dequant(AACContext * ac, float coef[1024], GetBit
> >  }
> >  
> >  static av_always_inline float flt16_round(float pf) {
> > +#ifdef ENABLE_IEEE754_PUN
> > +    union float754 tmp;
> > +    tmp.f = pf;
> > +    tmp.i = (tmp.i + 0x00008000U) & 0xFFFF0000U;
> > +    return tmp.f;
> > +#else
> 
> Are this things safe under strict aliasing rules?

Yes GCC does guarantee that it will work (all the accesses use
unionvalue.field syntax with the same union).