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

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

Samir asks

<<Does anyone know whether the Ada 95 standard say anything about the conformance
of Ada 95 to the IEEE 754 standard (i.e. floating point standard). I checked
some sections of the standard and could not find such information. Any pointers
(especially to the standard) are highly appreciated.
>>

The IEEE 754 standard is a combined hardware/software standard that requires
certain facilities to be available at the programming language level.

Most certainly the Ada 95 RM does not require IEEE conformance, since it is
designed to run on machines which do not implement reasonable hardware for
this purpose. The intention is that Ada 95 compilers map to the underlying
floating-point hardware, whether or not it is IEEE compliant or consistent.

Even on an IEEE machine, Ada 95 will implement only a subset of the
754 (or 854 remember the update) standard. 

However, a big difference in Ada 95, compared to Ada 83, is that
Ada 95 is "IEEE-ready", in that it is not inconsistent with the
standard, whereas with Ada 83 there were some definite glitches
in this respect.

What you need in Ada 95 is a package that provides required features,
plus some additional support from the compiler. My PhD thesis student
Sam Figueroa is working on a thesis that examines the issues of IEEE
compliance in high level languages, and one of the work products is
a complete binding for IEEE that we intend to fully implement in GNAT.

Robert Dewar