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Manual Reference Pages  - atomic_cas (3)

NAME
atomic_cas(3f) - [FORTRAN:INTRINSIC:ATOMIC] Atomic compare and swap

SYNTAX
call atomic_cas (atom, old, compare, new [, stat])

DESCRIPTION
atomic_cas compares the variable ATOM with the value of COMPARE; if the value is the same, ATOM is set to the value of NEW. Additionally, OLD is set to the value of ATOM that was used for the comparison. When STAT is present and the invocation was successful, it is assigned the value 0. If it is present and the invocation has failed, it is assigned a positive value; in particular, for a coindexed ATOM, if the remote image has stopped, it is assigned the value of iso_fortran_env’s stat_stopped_image and if the remote image has failed, the value stat_failed_image.

ARGUMENTS
ATOM Scalar coarray or coindexed variable of either integer type with atomic_int_kind kind or logical type with atomic_logical_kind kind.
OLD Scalar of the same type and kind as ATOM.
COMPARE
  Scalar variable of the same type and kind as ATOM.
NEW Scalar variable of the same type as ATOM. If kind is different, the value is converted to the kind of ATOM.
STAT (optional) Scalar default-kind integer variable.

EXAMPLE
Sample program: 

   program demo_atomic_cas
   use iso_fortran_env
   implicit none
   logical(atomic_logical_kind) :: atom[*], prev
      call atomic_cas(atom[1], prev, .false., .true.)
   end program demo_atomic_cas

STANDARD
[[TS 18508]] or later

CLASS
Atomic subroutine

SEE ALSO
atomic_define(3), atomic_ref(3), iso_fortran_env(3)

atomic_cas (3) March 11, 2021
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