Re: Fortran/PR19303 PATCH: Runtime selection of record markers forunformatted sequential io

[Tobias Schlüter <tobias dot schlueter at physik dot uni-muenchen dot de>]

(adding the Fortran list again)

Steve Ellcey wrote:
> The information I sent was from the Fortran Engineer who implemented it,
> I don't know if there is any externally available documentation but I
> will look around.

Well, that's as much authority as we can get without documentation.

> The description he gave was that they did check all the bits i.e.  the
> 32 bit value had to be -1.  I think the reasoning was to allow other
> negative values to be used for other encodings if that was ever needed.
> 
> I think you may be under the impression that the header size is either
> 32 bits or 64 bits, but actually the header size is either 32 bits or 96
> bits.  If the first 32 bits == -1, then the full size is encoded in the
> next 64 bits, with the initial 32 bits playing no part in the size
> encoding but simply indicating that a 64 bit value follows the 32 bit
> -1.  The trailer is also 96 bits with the 64 bit size followed by the 32
> bit -1 value.

Thanks for clarifying.

- Tobi