Re: Porting ADA source

["Steve" <nospam_steved94@comcast.net>]

"Giacomo Polizzi" <mio@.mio> wrote in message
news:cdfu3s$k1a$1@e3k.asi.ansaldo.it...
> Hello,
>
> I have to port an ADA program from an Unix DEC Alpha machine with a DEC
ADA
> compiler to a Linux pc machine with gnat (gcc) compiler.
>
> The task is to have, if possible, an unique source code compilable on both
> platforms but there are the following problems:
>
> 1) some system packages that execute the same kind of operations have
> different names in the two compilers
>
> 2) some system functions (for example mathematical function) have
different
> names in the two compilers

Have you considered obtaining GNAT for DEC Alpha Unix?  This may resolve
the different names issue.

>
> 3) the word length is 64 bits on DEC Alpha and 32 bits on pc so it is not
> always possible to use the same standard type (for example the long type
is
> 64 bits on Alpha and 32 bits on pc)
>
> 4) the standard type (long long) used by gcc on pc to solve the previous
> problem is not supported by the DEC ADA compiler

The basic answer here is: don't use the standard types.  Define your own
or use the definitions in the Interfaces package.  If you have a large base
or code using the predefined types, look for a tool to convert these to
your own definitions.

> 5) the different word length modifies some structure length used to define
> interface messages with other external programs
>

Use representation clauses to explicitly define structure layout the same on
both systems.

> Is there something like #IFDEF of C language that I can use in ADA ?
>
I believe GNAT has a pre-processor you could use, but I have never used it.

Steve
(The Duck)

> Is there any other kind of solution for the above problems ?
>
> Thanks to everybody
>
> Giacomo
>
>