Endianess

[Toon Moene]

>  This really sounds like a FAQ item to me, to clear this
>  up once and for all...

[ Good points snipped, thanks ]

>  If your data file contains only an unstructures stream
>  of 32 bit integers, you can use the following utility
>  program to reverse byte ordering:

This is, unfortunately, not true in general.  A Fortran unformatted  
sequential file *as generated by the f2c run time library* (and  
hence by g77, whether part of egcs or combined with gcc) has the  
following structure:

#-of-bytes-in-record, contents-of-record, #-of-bytes-in-previous-record
...

all concatenated in binary "words".

The problematic thing is the #-of-bytes-in-record.  On some systems  
this is a 32-bit integer, on some (like the Alpha) it is a 64-bit  
integer [An unfortunate situation we're not going to resolve without  
breaking backwards compatibility].

Hence, on Alpha, one can only reverse-endian a file with 64-bit  
INTEGERs and REALs in the simple way shown, and then s/he has to  
change the declaration of N1 and N2 thusly:

      INTEGER*8 N1, N2

and open the files with the following statement:

      OPEN(1,FORM='UNFORMATTED',ACCESS='DIRECT',RECL=8)
      OPEN(2,FORM='UNFORMATTED',ACCESS='DIRECT',RECL=8)

Hope this clarifies,
Toon.