NAME

       MPI_Buffer_detach -  Removes an existing buffer (for use in MPI_Bsend etc)

SYNOPSIS

       #include <mpi.h>
       int MPI_Buffer_detach(void *pbuf, int *psize)

OUTPUT PARAMETERS

       pbuf   - initial buffer address (choice)
       psize  - buffer size, in bytes (integer)

NOTES

       The  reason  that MPI_Buffer_detach returns the address and size of the buffer being detached is to allow
       nested libraries to replace and restore the buffer.  For example, consider

       int size, mysize, idummy;
       void *ptr, *myptr, *dummy;
       MPI_Buffer_detach(&ptr, &size);
       MPI_Buffer_attach(myptr, mysize);
       // ...library code...
       MPI_Buffer_detach(&dummy, &idummy);
       MPI_Buffer_attach(ptr, size);

       This is much like the action of the Unix signal routine and has the same strengths  (it  is  simple)  and
       weaknesses (it only works for nested usages).

       Note  that  for  this  approach  to work, MPI_Buffer_detach must return MPI_SUCCESS even when there is no
       buffer to detach.  In that case, it returns a size of zero.  The MPI 1.1 standard  for  MPI_BUFFER_DETACH
       contains the text

       The statements made in this section describe the behavior of MPI
       for buffered-mode sends. When no buffer is currently associated,
       MPI behaves as if a zero-sized buffer is associated with the
       process.

       This  could  be  read  as  applying  only  to  the various Bsend routines.  This implementation takes the
       position that this applies to MPI_BUFFER_DETACH as well.

NOTES FOR FORTRAN

       All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have an additional argument ierr at the
       end of the argument list.  ierr is an integer and has the same meaning as the return value of the routine
       in C.  In Fortran, MPI routines are subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

       The Fortran binding for this routine is different.   Because  Fortran  does  not  have  pointers,  it  is
       impossible  to  provide  a way to use the output of this routine to exchange buffers.  In this case, only
       the size field is set.

NOTES FOR C

       Even though the pbuf argument is declared as void * , it is really the address of a void  pointer  (i.e.,
       void ** ).  See the rationale in the MPI Standard for more details.

MORE INFORMATION

       For  more  information,  please  see the official MPI Forum web site, which contains the text of both the
       MPI-1 and MPI-2 standards.  These documents contain detailed information about each MPI function (most of
       which is not duplicated in these man pages).

       http://www.mpi-forum.org/

ACKNOWLEDGEMENTS

       The LAM Team would like the thank the MPICH Team for the handy program to generate man  pages  ("doctext"
       from  ftp://ftp.mcs.anl.gov/pub/sowing/sowing.tar.gz ), the initial formatting, and some initial text for
       most of the MPI-1 man pages.

LOCATION

       bufdetach.c

LAM/MPI 7.1.4                                       6/24/2006                               MPI_Buffer_detach(3)