Language Directives
*******************

This chapter describes the OmpSs-2 language, this is, all the necessary elements to understand how an OmpSs-2 application executes and/or behaves in a parallel architecture.
OmpSs-2 provides a simple path for users already familiarized with the OpenMP programming model to easily write (or port) their programs to OmpSs-2.

This description is completely guided by the list of OmpSs-2 directives.
In each of the following sections we will find a short description of the directive, its specific syntax, the list of clauses (including  the list of valid parameters for each clause and a short description for them).
In addition, each section finalizes with a simple example showing how this directive can be used in a valid OmpSs-2 program.

As is the case of OpenMP in C and C++, OmpSs-2 directives are specified using the `#pragma` mechanism (provided by the base language) and in Fortran they are specified using special comments that are identified by a unique sentinel.
The sentinel used in OmpSs-2 is `oss`.
Compilers will typically ignore OmpSs-2 directives if support is disabled or not provided.

.. highlight:: c

C/C++ format::

 #pragma oss directive-name [clause[ [,] clause] ... ] new-line

Fortran format::

 sentinel directive-name [clause[ [,] clause]...]

Where depend on Fortran fixed/free form:

* The sentinels for *fixed form* can be: ``!$oss``, ``c$oss`` or ``*$oss``.
  Sentinels must start in column 1. Continued directive line must have a character other than a space or a zero in column 6.
* The sentinel for *free form* must be ``!$oss``.
  This sentinel can appear in any column as long as is not preceeded by any character different than space. Continued directive line must have an ampersand (&).


.. include:: task.rst
.. include:: target.rst
.. include:: loop.rst
.. include:: taskwait.rst
.. include:: release.rst
.. include:: taskyield.rst
.. include:: atomic.rst
.. include:: critical.rst
.. include:: declare_reduction.rst
.. include:: assert.rst
.. include:: restrictions.rst