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Re: Processor-specific code
On Fri, 2005-04-15 at 15:50, Robert Dewar wrote:
> Richard Earnshaw wrote:
> > Not all environments can change the rounding mode dynamically. For
> > example, on the FPA co-processor for ARM, rounding is set by the
> > instruction selected -- so the concept of having an environment variable
> > to control this is meaningless.
> Right, such a feature obviously does not apply to hardware that is this
> far from the IEEE standard (which requires dynamic control). The Alpha
> architecture has similar problems.
Precisely which statement in IEEE 754-1985 states this? As far as I can
tell this standard is a mathematical abstraction for mapping floating
point onto machine types. Chapter 4 describes the required rounding
modes but definitely makes no statement saying that this has to be
selectable in a dynamic manner.