Re: Data types (was: Re: Access the neighbors of an element)

[Paul Kienzle]

Some more details:

On MIPS it is faster to convert to double and perform the multiplication
than to convert to a wider integer and do it.

On X86 the gains from using integer operations are much bigger than for
MIPS or PPC.

Even bigger gains for X86 32-bit architectures and LONGLONG double 
multiplication are possible by casting the address of the value as
a pointer to two long integers:

# elif defined(LONGLONG)
#if defined(LITTLEENDIAN_32)
  unsigned long *px = &x, *py = &y;
  if ( (px[1] && (py[1] || px[1]*y > LO)) || (py[1] && (py[1]*x > LO)) )
#else
  if ((x > LO && (y > LO || (x>>HALF)*y > LO)) || (y>LO && (y>>HALF)*x 
> LO))
#endif
    z = MX;
  else z = x * y;


- Paul



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