!    Implementation of the IEEE_EXCEPTIONS standard intrinsic module
!    Copyright (C) 2013-2023 Free Software Foundation, Inc.
!    Contributed by Francois-Xavier Coudert <fxcoudert@gcc.gnu.org>
! 
! This file is part of the GNU Fortran runtime library (libgfortran).
! 
! Libgfortran is free software; you can redistribute it and/or
! modify it under the terms of the GNU General Public
! License as published by the Free Software Foundation; either
! version 3 of the License, or (at your option) any later version.
! 
! Libgfortran is distributed in the hope that it will be useful,
! but WITHOUT ANY WARRANTY; without even the implied warranty of
! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
! GNU General Public License for more details.
! 
! Under Section 7 of GPL version 3, you are granted additional
! permissions described in the GCC Runtime Library Exception, version
! 3.1, as published by the Free Software Foundation.
! 
! You should have received a copy of the GNU General Public License and
! a copy of the GCC Runtime Library Exception along with this program;
! see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
! <http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "kinds.inc"
#include "c99_protos.inc"
#include "fpu-target.inc"

module IEEE_EXCEPTIONS

  implicit none
  private

! Derived types and named constants

  type, public :: IEEE_FLAG_TYPE
    private
    integer :: hidden
  end type

  type(IEEE_FLAG_TYPE), parameter, public :: &
    IEEE_INVALID        = IEEE_FLAG_TYPE(GFC_FPE_INVALID), &
    IEEE_OVERFLOW       = IEEE_FLAG_TYPE(GFC_FPE_OVERFLOW), &
    IEEE_DIVIDE_BY_ZERO = IEEE_FLAG_TYPE(GFC_FPE_ZERO), &
    IEEE_UNDERFLOW      = IEEE_FLAG_TYPE(GFC_FPE_UNDERFLOW), &
    IEEE_INEXACT        = IEEE_FLAG_TYPE(GFC_FPE_INEXACT)

  type(IEEE_FLAG_TYPE), parameter, public :: &
    IEEE_USUAL(3) = [ IEEE_OVERFLOW, IEEE_DIVIDE_BY_ZERO, IEEE_INVALID ], &
    IEEE_ALL(5)   = [ IEEE_USUAL, IEEE_UNDERFLOW, IEEE_INEXACT ]

  type, public :: IEEE_STATUS_TYPE
    private
    character(len=GFC_FPE_STATE_BUFFER_SIZE) :: hidden
  end type

  type, public :: IEEE_MODES_TYPE
    private
    integer :: rounding
    integer :: underflow
    integer :: halting
  end type

  interface IEEE_SUPPORT_FLAG
    module procedure IEEE_SUPPORT_FLAG_4, &
                     IEEE_SUPPORT_FLAG_8, &
#ifdef HAVE_GFC_REAL_10
                     IEEE_SUPPORT_FLAG_10, &
#endif
#ifdef HAVE_GFC_REAL_16
                     IEEE_SUPPORT_FLAG_16, &
#endif
                     IEEE_SUPPORT_FLAG_NOARG
  end interface IEEE_SUPPORT_FLAG

  public :: IEEE_SUPPORT_FLAG, IEEE_SUPPORT_HALTING
  public :: IEEE_SET_HALTING_MODE, IEEE_GET_HALTING_MODE
  public :: IEEE_SET_FLAG, IEEE_GET_FLAG
  public :: IEEE_SET_STATUS, IEEE_GET_STATUS
  public :: IEEE_SET_MODES, IEEE_GET_MODES

contains

! Fortran 2018: Saving and restoring floating-point modes
! (rounding modes, underflow mode, and halting mode)
! 
! For now, we only have one rounding mode for all kinds.
! Some targets could optimize getting/setting all modes at once, but for now
! we make three calls.  This code must be kept in sync with:
!   - IEEE_{GET,SET}_ROUNDING_MODE
!   - IEEE_{GET,SET}_UNDERFLOW_MODE
!   - IEEE_{GET,SET}_HALTING_MODE

  subroutine IEEE_GET_MODES (MODES)
    implicit none
    type(IEEE_MODES_TYPE), intent(out) :: MODES

    interface
      integer function helper_rounding() &
        bind(c, name="_gfortrani_get_fpu_rounding_mode")
      end function
      integer function helper_underflow() &
        bind(c, name="_gfortrani_get_fpu_underflow_mode")
      end function
      pure integer function helper_halting() &
          bind(c, name="_gfortrani_get_fpu_trap_exceptions")
      end function
    end interface

    MODES%rounding = helper_rounding()
    MODES%underflow = helper_underflow()
    MODES%halting = helper_halting()
  end subroutine

  subroutine IEEE_SET_MODES (MODES)
    implicit none
    type(IEEE_MODES_TYPE), intent(in) :: MODES

    interface
      subroutine helper_rounding(val) &
          bind(c, name="_gfortrani_set_fpu_rounding_mode")
        integer, value :: val
      end subroutine
      subroutine helper_underflow(val) &
          bind(c, name="_gfortrani_set_fpu_underflow_mode")
        integer, value :: val
      end subroutine
      pure subroutine helper_halting(trap, notrap) &
          bind(c, name="_gfortrani_set_fpu_trap_exceptions")
        integer, intent(in), value :: trap, notrap
      end subroutine
    end interface

    call helper_rounding(MODES%rounding)
    call helper_underflow(MODES%underflow)
    call helper_halting(MODES%halting, NOT(MODES%halting))
  end subroutine

! Saving and restoring floating-point status

  subroutine IEEE_GET_STATUS (STATUS_VALUE)
    implicit none
    type(IEEE_STATUS_TYPE), intent(out) :: STATUS_VALUE

    interface
      subroutine helper(ptr) &
          bind(c, name="_gfortrani_get_fpu_state")
        use, intrinsic :: iso_c_binding, only : c_char
        character(kind=c_char) :: ptr(*)
      end subroutine
    end interface

    call helper(STATUS_VALUE%hidden)
  end subroutine

  subroutine IEEE_SET_STATUS (STATUS_VALUE)
    implicit none
    type(IEEE_STATUS_TYPE), intent(in) :: STATUS_VALUE

    interface
      subroutine helper(ptr) &
          bind(c, name="_gfortrani_set_fpu_state")
        use, intrinsic :: iso_c_binding, only : c_char
        character(kind=c_char) :: ptr(*)
      end subroutine
    end interface

    call helper(STATUS_VALUE%hidden)
  end subroutine

! Getting and setting flags

  elemental subroutine IEEE_GET_FLAG (FLAG, FLAG_VALUE)
    implicit none
    type(IEEE_FLAG_TYPE), intent(in) :: FLAG
    logical, intent(out) :: FLAG_VALUE

    interface
      pure integer function helper() &
        bind(c, name="_gfortrani_get_fpu_except_flags")
      end function
    end interface

    FLAG_VALUE = (IAND(helper(), FLAG%hidden) /= 0)
  end subroutine

  elemental subroutine IEEE_SET_FLAG (FLAG, FLAG_VALUE)
    implicit none
    type(IEEE_FLAG_TYPE), intent(in) :: FLAG
    logical, intent(in) :: FLAG_VALUE

    interface
      pure subroutine helper(set, clear) &
          bind(c, name="_gfortrani_set_fpu_except_flags")
        integer, intent(in), value :: set, clear
      end subroutine
    end interface

    if (FLAG_VALUE) then
      call helper(FLAG%hidden, 0)
    else
      call helper(0, FLAG%hidden)
    end if
  end subroutine

! Querying and changing the halting mode

  elemental subroutine IEEE_GET_HALTING_MODE (FLAG, HALTING)
    implicit none
    type(IEEE_FLAG_TYPE), intent(in) :: FLAG
    logical, intent(out) :: HALTING

    interface
      pure integer function helper() &
          bind(c, name="_gfortrani_get_fpu_trap_exceptions")
      end function
    end interface

    HALTING = (IAND(helper(), FLAG%hidden) /= 0)
  end subroutine

  elemental subroutine IEEE_SET_HALTING_MODE (FLAG, HALTING)
    implicit none
    type(IEEE_FLAG_TYPE), intent(in) :: FLAG
    logical, intent(in) :: HALTING

    interface
      pure subroutine helper(trap, notrap) &
          bind(c, name="_gfortrani_set_fpu_trap_exceptions")
        integer, intent(in), value :: trap, notrap
      end subroutine
    end interface

    if (HALTING) then
      call helper(FLAG%hidden, 0)
    else
      call helper(0, FLAG%hidden)
    end if
  end subroutine

! Querying support

  pure logical function IEEE_SUPPORT_HALTING (FLAG)
    implicit none
    type(IEEE_FLAG_TYPE), intent(in) :: FLAG

    interface
      pure integer function helper(flag) &
          bind(c, name="_gfortrani_support_fpu_trap")
        integer, intent(in), value :: flag
      end function
    end interface

    IEEE_SUPPORT_HALTING = (helper(FLAG%hidden) /= 0)
  end function

  pure logical function IEEE_SUPPORT_FLAG_NOARG (FLAG)
    implicit none
    type(IEEE_FLAG_TYPE), intent(in) :: FLAG

    interface
      pure integer function helper(flag) &
          bind(c, name="_gfortrani_support_fpu_flag")
        integer, intent(in), value :: flag
      end function
    end interface

    IEEE_SUPPORT_FLAG_NOARG = (helper(FLAG%hidden) /= 0)
  end function

  pure logical function IEEE_SUPPORT_FLAG_4 (FLAG, X) result(res)
    implicit none
    type(IEEE_FLAG_TYPE), intent(in) :: FLAG
    real(kind=4), intent(in) :: X
    res = IEEE_SUPPORT_FLAG_NOARG(FLAG)
  end function

  pure logical function IEEE_SUPPORT_FLAG_8 (FLAG, X) result(res)
    implicit none
    type(IEEE_FLAG_TYPE), intent(in) :: FLAG
    real(kind=8), intent(in) :: X
    res = IEEE_SUPPORT_FLAG_NOARG(FLAG)
  end function

#ifdef HAVE_GFC_REAL_10
  pure logical function IEEE_SUPPORT_FLAG_10 (FLAG, X) result(res)
    implicit none
    type(IEEE_FLAG_TYPE), intent(in) :: FLAG
    real(kind=10), intent(in) :: X
    res = IEEE_SUPPORT_FLAG_NOARG(FLAG)
  end function
#endif

#ifdef HAVE_GFC_REAL_16
  pure logical function IEEE_SUPPORT_FLAG_16 (FLAG, X) result(res)
    implicit none
    type(IEEE_FLAG_TYPE), intent(in) :: FLAG
    real(kind=16), intent(in) :: X
    res = IEEE_SUPPORT_FLAG_NOARG(FLAG)
  end function
#endif

end module IEEE_EXCEPTIONS