Xref: utzoo comp.sys.dec:724 comp.os.vms:7539
Path: utzoo!attcan!uunet!husc6!mailrus!ames!ncar!acdpyr!pack
From: pack@acdpyr.ucar.edu (Dan Packman)
Newsgroups: comp.sys.dec,comp.os.vms
Subject: Re: difference between vax floating point representation and IEEE
Summary: IEEE floating point to/from VAX floating point
Keywords: IEEE vax floating
Message-ID: <471@ncar.ucar.edu>
Date: 22 Jul 88 22:37:55 GMT
References: <2256@hubcap.UUCP>
Sender: news@ncar.ucar.edu
Reply-To: pack@acdpyr.UCAR.EDU (Dan Packman)
Organization: Atmospheric Chemistry Division/NCAR, Boulder CO
Lines: 62

In article <2256@hubcap.UUCP> ghosh@hubcap.UUCP (Amitava Ghosh) writes:
>does anyone know what the difference is between the IEEE floating
>point representation and the way the VAX stores numbers. If so
>how does one convert from one format to the other...
The following program converts from vax f format to IEEE (UNIX point of view)
--------cut here-------------
      subroutine vax2lcl(n,iarray)
      dimension iarray(n)
      character*1 conv(4),ccc
      integer iconv
      equivalence (iconv,conv)
c Convert from vax floating point f format to pyramid IEEE single
      do 10 i=1,n
        iconv=iarray(i)
        if (iconv.ne.0) then
         ccc=conv(1)
         iii=ichar(conv(2))-1
         if (iii.lt.0)then
           write(0,100)iconv
 100       format(' vax2lcl: overflow int in =',i10)
           call exit(1)
         endif
         conv(1)=char(iii)
         conv(2)=ccc
         ccc=conv(3)
         conv(3)=conv(4)
         conv(4)=ccc
         iarray(i)=iconv
        endif
  10  continue
      return
      end
--------cut here-------------
The following converts an array of IEEE single floats to vax floats
It is written to work on a VAX/VMS machine
--------cut here-------------
      subroutine pyr2lcl(n,iarray)
      dimension iarray(n)
      byte conv(4),ccc
      integer iconv
      equivalence (iconv,conv)
c Convert from pyramid IEEE single to vax floating point f format
      do 10 i=1,n
        iconv=iarray(i)
        if (iconv.ne.0) then
         ccc=conv(2)
         iii=conv(1)+1
         if (iii.gt.255)then
           write(0,100)iconv
 100       format(' pyr2lcl: overflow int in =',i10)
           call exit(1)
         endif
         conv(2)=iii
         conv(1)=ccc
         ccc=conv(3)
         conv(3)=conv(4)
         conv(4)=ccc
         iarray(i)=iconv
        endif
  10  continue
      return
      end