Re: floating point problem

[eachus@spectre.mitre.org (Robert I. Eachus)]

   Robert Dewar said:

   > Sure there are tons of such machines, but for serious development work,
   > which is what GNAT is intended for, it is silly to use an ancient 386

In article <1997Mar16.113256.1@eisner> kilgallen@eisner.decus.org (Larry Kilgallen) writes:

   > That is too bad.  I had hoped GNAT might be useful for deployment.
   > Just to make sure we are on the same wavelength, my concern is
   > entirely with what happens at runtime with generated programs.
   > For running the compiler I can buy (actually already have) some
   > appropriate machines.

   Ah, I see the confusion.  If you want programs that will run on
"any" PC, you need to avoid the use of floating point in your
programs.  (And to test on a 386 with no FPU, just to check.)  The
GNAT compiler itself uses floating point, in some cases even when your
program doesn't, so you need to develop on an FP equipped machine.
(And the random number generator is one library package which uses
float, even if your program doesn't explicitly.  Any others?)

   Now for some value added.  Several years ago for a procurement, we
went looking for Ada (83) compilers that could be validated on PCs
without an FPU.  We couldn't find one, we couldn't find a compiler
vendor willing to build and sell one, and we couldn't even find a
compiler which ran on a machine with an FPU and produced validatable
code for a non-FPU machine.  This was back when the 286 and 386 were
the "standard" CPU chips.

    However, in the machines which used Motorola 680x0 chips, all
machines/compilers seemed to support emulation of the FPU if not
present.  In fact some compilers gave you a choice between non-IEEE
(and therefore non-hardware) floating-point libraries, and those which
relied on IEEE hardware support, but ran much slower if the emulator
was invoked.
--

					Robert I. Eachus

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