From: "Marc Snir ((914) 945-3204)" <[email-masked]>
Date: Sun, 10 Jul 94 20:28:42 EDT

cc: frankeh, gropp at mcs.anl.gov, otto at cse.ogi.edu
Subject: Correction of Bill Gropp
Reply-To: [email-masked]

Difference between 2 pointers to the same storage area should be of type
MPI_Aint, rather than int.  This is the assumption we go by in the
definition of MPI_Type_hvector and MPI_Tpe_hindexed.
If we want to be consistent, then we should use the same type MPI_Aint in
the functions that return such difference; thus,
MPI_Type_extent(..., MPI_Aint* extent)
MPI_Type_size(..., MPI_Aint* size)
MPI_Type_lb(..., MPI_Aint* displacement)
MPI_Type_ub(..., MPI_Aint *displacement)

Unless somebody objects, I would take this to be a bug in the current text,
which will be corrected as outlined above.

A similar issue:  Should the arguments POSITION and OUTCOUNT
in  MPI_PACK be of type int (as they are now) or of type MPI_Aint?
I.e., do we want to allow for a buffer with more than 2 Gbytes?

Finally, a syntactic correction:  MPI_PACK(..., OUTCOUNT,...) should be
MPI_PACK(..., OUTSIZE,...), similar to MPI_UNPACK(..., INSIZE,...).
OUTCOUNT is not a count of elements inserted in the buffer, but the
total buffer size.