Re: Does Ada 95 conform to the IEEE 754 floating point standard?

[dewar@merv.cs.nyu.edu (Robert Dewar)]

Samir asks

<<        I was wondering whether Ada 95 conform to the IEEE 754 floating point
standard. Pointers to URLs, papers, etc. are highly appreciated.
>>

Unlike the Language Independent Arithmetic standard, IEEE is NOT a standard
about what programming languages should do. Rather it is a standard that
specifies a set of functions that must be available.

Obviously Ada itself does not mandate IEEE, because then it could not be
implemented with reasonable efficiency on non-IEEE machines, or more
accurately on machines not providing full IEEE facilities in hardware.

Java *does* mandate such support, and a consequence is that it is impossible
to implement Java with reasonable efficiency on machines (like the SGI
MIPS R10000, or the Alpha) which do not provide full IEEE support in
hardware. In practice everyone just ignores this requirement in java and
uses native arithmetic, assuming it is near enough.

Ada 95 is carefully designed to be compatible with the IEEE 754 and 854
standards, but to actually provide a full IEEE environment requires, in
addition to operation on a machine fully supporting IEEE semantics, a
package of appropriate interface definitions.

A student of mine, Sam Figueroa, is working on a thesis that among other
aspects, will provide a full implementation of these interfaces, and we
expect to be providing this with GNAT sometime in the future.