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_allocator_handle_t, which must be an implementation-defined (for C++ possibly scoped) enum type with at least the omp_null_allocator enumerator with the value zero and an enumerator for each predefined memory allocator in 6.3;
• omp_atv_default, which is an instance of a type compatible with omp_uintptr_t with the value -1;
• The type omp_control_tool_result_t;
• The type omp_control_tool_t;
• The type omp_depend_t;
• The type omp_event_handle_t, which must be an implementation-defined (for C++ possibly scoped) enum type;
• The enumerator omp_initial_device with value -1;
• The type omp_interop_t, which must be an implementation-defined integral or pointer type;
• The type omp_interop_fr_t, which must be an implementation-defined enum type with enumerators named omp_ifr_name where name is a foreign runtime name that is defined in the OpenMP Additional Definitions document;
• The type omp_intptr_t, which is a signed integer type that is at least the size of a pointer on any device;
• The enumerator omp_invalid_device with an implementation-defined value less than -1;
• The type omp_lock_hint_t (deprecated);
• The type omp_lock_t;
• The type omp_memspace_handle_t, which must be an implementation-defined (for C++ possibly scoped) enum type with an enumerator for at least each predefined memory space in 6.1;
• The type omp_nest_lock_t;
• The type omp_pause_resource_t;
• The type omp_proc_bind_t;
• The type omp_sched_t;
• The type omp_sync_hint_t; and
• The type omp_uintptr_t, which is an unsigned integer type capable of holding a pointer on any device.

The OpenMP enumeration types provided in the omp.h header file shall not be scoped enumeration types unless explicitly allowed.

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 6.3 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 module named omp_lib or a Fortran include file named omp_lib.h. Whether the omp_lib.h file provides derived-type definitions or those routines that require an explicit interface is implementation defined. Whether the include file or the module file (or both) is provided is also implementation defined.

These files also define the following:

• The default integer named constant omp_allocator_handle_kind;
• An integer named constant of kind omp_allocator_handle_kind for each predefined memory allocator in 6.3;
• The default integer named constant omp_alloctrait_key_kind;
• The default integer named constant omp_alloctrait_val_kind;
• The default integer named constant omp_control_tool_kind;
• The default integer named constant omp_control_tool_result_kind;
• The default integer named constant omp_depend_kind;
• The default integer named constant omp_event_handle_kind;
• The default integer named constant omp_initial_device with value -1;
• The default integer named constant omp_interop_kind;
• The default integer named constant omp_interop_fr_kind;
• An integer named constant omp_ifr_name of kind omp_interop_fr_kind for each name that is a foreign runtime name that is defined in the OpenMP Additional Definitions document;
• The default integer named constant omp_invalid_device with an implementation-defined value less than -1;
• The default integer named constant omp_lock_hint_kind (deprecated);
• The default integer named constant omp_lock_kind;
• The default integer named constant omp_memspace_handle_kind;
• An integer named constant of kind omp_memspace_handle_kind for each predefined memory space in 6.1;
• The default integer named constant omp_nest_lock_kind;
• The default integer named constant omp_pause_resource_kind;
• The default integer named constant omp_proc_bind_kind;
• The default integer named constant omp_sched_kind;
• The default integer named constant omp_sync_hint_kind; and
• The default integer named constant 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 3.3).

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 is implementation defined.