.. _subsec:library_constants:

Library Constants
=================

The NVSHMEM library provides a set of compile-time constants that may be
used to specify options to API routines, provide implementation-specific
parameters, or return information about the implementation.

.. c:var:: NVSHMEM_THREAD_SINGLE

The NVSHMEM thread support level which specifies that the program must
not be multithreaded. See
Section :ref:`subsec:thread_support` for more
detail about its use.

.. c:var:: NVSHMEM_THREAD_FUNNELED

The NVSHMEM thread support level which specifies that the program may be
multithreaded but must ensure that only the main thread invokes the
NVSHMEM interfaces. See
Section :ref:`subsec:thread_support` for more
detail about its use.

.. c:var:: NVSHMEM_THREAD_SERIALIZED

The NVSHMEM thread support level which specifies that the program may be
multithreaded but must ensure that the NVSHMEM interfaces are not
invoked concurrently by multiple threads. See
Section :ref:`subsec:thread_support` for more
detail about its use.

.. c:var:: NVSHMEM_THREAD_MULTIPLE

The NVSHMEM thread support level which specifies that the program may be
multithreaded and any thread may invoke the NVSHMEM interfaces. See
Section :ref:`subsec:thread_support` for more
detail about its use.

.. c:var:: NVSHMEM_TEAM_INVALID

A value corresponding to an invalid team. This value can be used to
initialize or update team handles to indicate that they do not reference
a valid team. When managed in this way, applications can use an equality
comparison to test whether a given team handle references a valid team.

.. c:var:: NVSHMEM_SYNC_VALUE

The value used to initialize the elements of *pSync* arrays. The value
of this constant is implementation specific. See
Section :ref:`subsec:coll` for more detail about its use.

.. c:var:: NVSHMEM_SYNC_SIZE

Length of a work array that can be used with any NVSHMEM collective
communication operation. Work arrays sized for specific operations may
consume less memory. The value of this constant is implementation
specific. See Section :ref:`subsec:coll` for more detail
about its use.

.. c:var:: NVSHMEM_BCAST_SYNC_SIZE

Length of the *pSync* arrays needed for broadcast routines. The value of
this constant is implementation specific. See
Section :ref:`subsec:shmem_broadcast` for more
detail about its use.

.. c:var:: NVSHMEM_REDUCE_SYNC_SIZE

Length of the work arrays needed for reduction routines. The value of
this constant is implementation specific. See
Section :ref:`subsec:shmem_reductions` for
more detail about its use.

.. c:var:: NVSHMEM_BARRIER_SYNC_SIZE

Length of the work array needed for barrier routines. The value of this
constant is implementation specific. See
Section :ref:`subsec:shmem_barrier` for more
detail about its use.

.. c:var:: NVSHMEM_COLLECT_SYNC_SIZE

Length of the work array needed for collect routines. The value of this
constant is implementation specific. See
Section :ref:`subsec:shmem_collect` for more
detail about its use.

.. c:var:: NVSHMEM_ALLTOALL_SYNC_SIZE

Length of the work array needed for *nvshmem_alltoall* routines. The
value of this constant is implementation specific. See
Section :ref:`subsec:shmem_alltoall` for more
detail about its use.

.. c:var:: NVSHMEM_REDUCE_MIN_WRKDATA_SIZE

Minimum length of work arrays used in various collective routines.

.. c:var:: NVSHMEM_MAJOR_VERSION

Integer representing the major version of OpenSHMEM Specification in
use.

.. c:var:: NVSHMEM_MINOR_VERSION

Integer representing the minor version of OpenSHMEM Specification in
use.

.. c:var:: NVSHMEM_MAX_NAME_LEN

Integer representing the maximum length of *NVSHMEM_VENDOR_STRING*.

.. c:var:: NVSHMEM_VENDOR_STRING

String representing vendor defined information of size at most
*NVSHMEM_MAX_NAME_LEN*. In *C/C++*, the string is terminated by a null
character.

.. c:var:: NVSHMEM_CMP_EQ

An integer constant expression corresponding to the “equal to”
comparison operation. See
Section :ref:`subsec:p2p_intro` for more detail about
its use.

.. c:var:: NVSHMEM_CMP_NE

An integer constant expression corresponding to the “not equal to”
comparison operation. See
Section :ref:`subsec:p2p_intro` for more detail about
its use.

.. c:var:: NVSHMEM_CMP_LT

An integer constant expression corresponding to the “less than”
comparison operation. See
Section :ref:`subsec:p2p_intro` for more detail about
its use.

.. c:var:: NVSHMEM_CMP_LE

An integer constant expression corresponding to the “less than or equal
to” comparison operation. See
Section :ref:`subsec:p2p_intro` for more detail about
its use.

.. c:var:: NVSHMEM_CMP_GT

An integer constant expression corresponding to the “greater than”
comparison operation. See
Section :ref:`subsec:p2p_intro` for more detail about
its use.

.. c:var:: NVSHMEM_CMP_GE

An integer constant expression corresponding to the “greater than or
equal to” comparison operation. See
Section :ref:`subsec:p2p_intro` for more detail about
its use.