|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
<HTML>
|
|
Packit Service |
c5cf8c |
<HEAD>
|
|
Packit Service |
c5cf8c |
<META NAME="GENERATOR" CONTENT="DOCTEXT">
|
|
Packit Service |
c5cf8c |
<TITLE>MPI_Type_struct</TITLE>
|
|
Packit Service |
c5cf8c |
</HEAD>
|
|
Packit Service |
c5cf8c |
<BODY BGCOLOR="FFFFFF">
|
|
Packit Service |
c5cf8c |
MPI_Type_struct
|
|
Packit Service |
c5cf8c |
Creates a struct datatype
|
|
Packit Service |
c5cf8c |
Synopsis
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
int MPI_Type_struct(int count,
|
|
Packit Service |
c5cf8c |
int *array_of_blocklengths,
|
|
Packit Service |
c5cf8c |
MPI_Aint * array_of_displacements,
|
|
Packit Service |
c5cf8c |
MPI_Datatype * array_of_types, MPI_Datatype * newtype)
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Input Parameters
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
count number of blocks (integer) -- also number of
|
|
Packit Service |
c5cf8c |
entries in arrays array_of_types ,
|
|
Packit Service |
c5cf8c |
array_of_displacements and array_of_blocklengths
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
array_of_blocklengths number of elements in each block (array)
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
array_of_displacements byte displacement of each block (array)
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
array_of_types type of elements in each block (array
|
|
Packit Service |
c5cf8c |
of handles to datatype objects)
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Output Parameters
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
newtype new datatype (handle)
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Deprecated Function
|
|
Packit Service |
c5cf8c |
The MPI-2 standard deprecated a number of routines because MPI-2 provides
|
|
Packit Service |
c5cf8c |
better versions. This routine is one of those that was deprecated. The
|
|
Packit Service |
c5cf8c |
routine may continue to be used, but new code should use the replacement
|
|
Packit Service |
c5cf8c |
routine.
|
|
Packit Service |
c5cf8c |
The replacement for this routine is <tt>MPI_Type_create_struct
|
|
Packit Service |
c5cf8c |
</tt>
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Notes
|
|
Packit Service |
c5cf8c |
If an upperbound is set explicitly by using the MPI datatype <tt>MPI_UB</tt>, the
|
|
Packit Service |
c5cf8c |
corresponding index must be positive.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
The MPI standard originally made vague statements about padding and alignment;
|
|
Packit Service |
c5cf8c |
this was intended to allow the simple definition of structures that could
|
|
Packit Service |
c5cf8c |
be sent with a count greater than one. For example,
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
struct { int a; char b; } foo;
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
may have <tt>sizeof(foo) > sizeof(int) + sizeof(char)</tt>; for example,
|
|
Packit Service |
c5cf8c |
<tt>sizeof(foo) == 2*sizeof(int)</tt>. The initial version of the MPI standard
|
|
Packit Service |
c5cf8c |
defined the extent of a datatype as including an epsilon that would have
|
|
Packit Service |
c5cf8c |
allowed an implementation to make the extent an MPI datatype
|
|
Packit Service |
c5cf8c |
for this structure equal to <tt>2*sizeof(int)</tt>.
|
|
Packit Service |
c5cf8c |
However, since different systems might define different paddings, there was
|
|
Packit Service |
c5cf8c |
much discussion by the MPI Forum about what was the correct value of
|
|
Packit Service |
c5cf8c |
epsilon, and one suggestion was to define epsilon as zero.
|
|
Packit Service |
c5cf8c |
This would have been the best thing to do in MPI 1.0, particularly since
|
|
Packit Service |
c5cf8c |
the <tt>MPI_UB</tt> type allows the user to easily set the end of the structure.
|
|
Packit Service |
c5cf8c |
Unfortunately, this change did not make it into the final document.
|
|
Packit Service |
c5cf8c |
Currently, this routine does not add any padding, since the amount of
|
|
Packit Service |
c5cf8c |
padding needed is determined by the compiler that the user is using to
|
|
Packit Service |
c5cf8c |
build their code, not the compiler used to construct the MPI library.
|
|
Packit Service |
c5cf8c |
A later version of MPICH may provide for some natural choices of padding
|
|
Packit Service |
c5cf8c |
(e.g., multiple of the size of the largest basic member), but users are
|
|
Packit Service |
c5cf8c |
advised to never depend on this, even with vendor MPI implementations.
|
|
Packit Service |
c5cf8c |
Instead, if you define a structure datatype and wish to send or receive
|
|
Packit Service |
c5cf8c |
multiple items, you should explicitly include an <tt>MPI_UB</tt> entry as the
|
|
Packit Service |
c5cf8c |
last member of the structure. For example, the following code can be used
|
|
Packit Service |
c5cf8c |
for the structure foo
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
blen[0] = 1; array_of_displacements[0] = 0; oldtypes[0] = MPI_INT;
|
|
Packit Service |
c5cf8c |
blen[1] = 1; array_of_displacements[1] = &foo.b - &foo; oldtypes[1] = MPI_CHAR;
|
|
Packit Service |
c5cf8c |
blen[2] = 1; array_of_displacements[2] = sizeof(foo); oldtypes[2] = MPI_UB;
|
|
Packit Service |
c5cf8c |
MPI_Type_struct(3, blen, array_of_displacements, oldtypes, &newtype);
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Thread and Interrupt Safety
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
This routine is thread-safe. This means that this routine may be
|
|
Packit Service |
c5cf8c |
safely used by multiple threads without the need for any user-provided
|
|
Packit Service |
c5cf8c |
thread locks. However, the routine is not interrupt safe. Typically,
|
|
Packit Service |
c5cf8c |
this is due to the use of memory allocation routines such as <tt>malloc
|
|
Packit Service |
c5cf8c |
</tt>or other non-MPICH runtime routines that are themselves not interrupt-safe.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Notes for Fortran
|
|
Packit Service |
c5cf8c |
All MPI routines in Fortran (except for <tt>MPI_WTIME</tt> and <tt>MPI_WTICK</tt>) have
|
|
Packit Service |
c5cf8c |
an additional argument <tt>ierr</tt> at the end of the argument list. <tt>ierr
|
|
Packit Service |
c5cf8c |
</tt>is an integer and has the same meaning as the return value of the routine
|
|
Packit Service |
c5cf8c |
in C. In Fortran, MPI routines are subroutines, and are invoked with the
|
|
Packit Service |
c5cf8c |
<tt>call</tt> statement.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
All MPI objects (e.g., <tt>MPI_Datatype</tt>, <tt>MPI_Comm</tt>) are of type <tt>INTEGER
|
|
Packit Service |
c5cf8c |
</tt>in Fortran.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Errors
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
All MPI routines (except <tt>MPI_Wtime</tt> and <tt>MPI_Wtick</tt>) return an error value;
|
|
Packit Service |
c5cf8c |
C routines as the value of the function and Fortran routines in the last
|
|
Packit Service |
c5cf8c |
argument. Before the value is returned, the current MPI error handler is
|
|
Packit Service |
c5cf8c |
called. By default, this error handler aborts the MPI job. The error handler
|
|
Packit Service |
c5cf8c |
may be changed with <tt>MPI_Comm_set_errhandler</tt> (for communicators),
|
|
Packit Service |
c5cf8c |
<tt>MPI_File_set_errhandler</tt> (for files), and <tt>MPI_Win_set_errhandler</tt> (for
|
|
Packit Service |
c5cf8c |
RMA windows). The MPI-1 routine <tt>MPI_Errhandler_set</tt> may be used but
|
|
Packit Service |
c5cf8c |
its use is deprecated. The predefined error handler
|
|
Packit Service |
c5cf8c |
<tt>MPI_ERRORS_RETURN</tt> may be used to cause error values to be returned.
|
|
Packit Service |
c5cf8c |
Note that MPI does not guarentee that an MPI program can continue past
|
|
Packit Service |
c5cf8c |
an error; however, MPI implementations will attempt to continue whenever
|
|
Packit Service |
c5cf8c |
possible.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
MPI_SUCCESS No error; MPI routine completed successfully.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
MPI_ERR_TYPE Invalid datatype argument. Additionally, this error can
|
|
Packit Service |
c5cf8c |
occur if an uncommitted MPI_Datatype (see <tt>MPI_Type_commit</tt>) is used
|
|
Packit Service |
c5cf8c |
in a communication call.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
MPI_ERR_COUNT Invalid count argument. Count arguments must be
|
|
Packit Service |
c5cf8c |
non-negative; a count of zero is often valid.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
MPI_ERR_INTERN This error is returned when some part of the MPICH
|
|
Packit Service |
c5cf8c |
implementation is unable to acquire memory.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
</BODY></HTML>
|