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. R.
