The library routines are external functions with “C” linkage.

Prototypes for the C/C++ runtime library routines described in this chapter shall be provided in a header file named omp.h. This file also defines the following:

• The type omp_lock_t;
• The type omp_nest_lock_t;
• The type omp_sync_hint_t;
• The type omp_lock_hint_t (deprecated);
• The type omp_sched_t;
• The type omp_proc_bind_t;
• The type omp_control_tool_t;
• The type omp_control_tool_result_t;
• The type omp_depend_t;
• The type omp_memspace_handle_t, which must be an implementation-defined enum type with an enumerator for at least each predefined memory space in Table 2.8 on page 427;
• The type omp_allocator_handle_t, which must be an implementation-defined enum type with at least the omp_null_allocator enumerator with the value zero and an enumerator for each predefined memory allocator in Table 2.10 on page 434;
• The type omp_uintptr_t, which is an unsigned integer type capable of holding a pointer on any device;
• The type omp_pause_resource_t; and
• The type omp_event_handle_t, which must be an implementation-defined enum type.

The omp.h header file also defines a class template that models the Allocator concept in the omp::allocator namespace for each predefined memory allocator in Table 2.10 on page 434 for which the name includes neither the omp_ prefix nor the _alloc suffix.

The OpenMP Fortran API runtime library routines are external procedures. The return values of these routines are of default kind, unless otherwise specified.

Interface declarations for the OpenMP Fortran runtime library routines described in this chapter shall be provided in the form of a Fortran include file named omp_lib.h or a Fortran 90 module named omp_lib. It is implementation defined whether the include file or the module file (or both) is provided.

These files also define the following:

• The integer parameter omp_lock_kind;
• The integer parameter omp_nest_lock_kind;
• The integer parameter omp_sync_hint_kind;
• The integer parameter omp_lock_hint_kind (deprecated);
• The integer parameter omp_sched_kind;
• The integer parameter omp_proc_bind_kind;
• The integer parameter omp_control_tool_kind;
• The integer parameter omp_control_tool_result_kind;
• The integer parameter omp_depend_kind;
• The integer parameter omp_memspace_handle_kind;
• The integer parameter omp_allocator_handle_kind;
• The integer parameter omp_alloctrait_key_kind;
• The integer parameter omp_alloctrait_val_kind;
• An integer parameter of kind omp_memspace_handle_kind for each predefined memory space in Table 2.8 on page 427;
• An integer parameter of kind omp_allocator_handle_kind for each predefined memory allocator in Table 2.10 on page 434;
• The integer parameter omp_pause_resource_kind;
• The integer parameter omp_event_handle_kind; and
• The integer parameter openmp_version with a value yyyymm where yyyy and mm are the year and month designations of the version of the OpenMP Fortran API that the implementation supports; this value matches that of the C preprocessor macro _OPENMP, when a macro preprocessor is supported (see Section 2.2 on page 128).

It is implementation defined whether any of the OpenMP runtime library routines that take an argument are extended with a generic interface so arguments of different KIND type can be accommodated.