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!===-- module/ieee_arithmetic.f90 ------------------------------------------===!
!
! Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
! See https://llvm.org/LICENSE.txt for license information.
! SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
!
!===------------------------------------------------------------------------===!
! See Fortran 2018, clause 17.2
module ieee_arithmetic
type :: ieee_class_type
private
integer(kind=1) :: which = 0
end type ieee_class_type
type(ieee_class_type), parameter :: &
ieee_signaling_nan = ieee_class_type(1), &
ieee_quiet_nan = ieee_class_type(2), &
ieee_negative_inf = ieee_class_type(3), &
ieee_negative_normal = ieee_class_type(4), &
ieee_negative_denormal = ieee_class_type(5), &
ieee_negative_zero = ieee_class_type(6), &
ieee_positive_zero = ieee_class_type(7), &
ieee_positive_subnormal = ieee_class_type(8), &
ieee_positive_normal = ieee_class_type(9), &
ieee_positive_inf = ieee_class_type(10), &
ieee_other_value = ieee_class_type(11)
type(ieee_class_type), parameter :: &
ieee_negative_subnormal = ieee_negative_denormal, &
ieee_positive_denormal = ieee_negative_subnormal
type :: ieee_round_type
private
integer(kind=1) :: mode = 0
end type ieee_round_type
type(ieee_round_type), parameter :: &
ieee_nearest = ieee_round_type(1), &
ieee_to_zero = ieee_round_type(2), &
ieee_up = ieee_round_type(3), &
ieee_down = ieee_round_type(4), &
ieee_away = ieee_round_type(5), &
ieee_other = ieee_round_type(6)
interface operator(==)
module procedure class_eq
module procedure round_eq
end interface operator(==)
interface operator(/=)
module procedure class_ne
module procedure round_ne
end interface operator(/=)
! See Fortran 2018, 17.10 & 17.11
interface ieee_class
module procedure ieee_class_a2
module procedure ieee_class_a3
module procedure ieee_class_a4
module procedure ieee_class_a8
module procedure ieee_class_a10
module procedure ieee_class_a16
end interface ieee_class
interface ieee_copy_sign
module procedure ieee_copy_sign_a2
module procedure ieee_copy_sign_a3
module procedure ieee_copy_sign_a4
module procedure ieee_copy_sign_a8
module procedure ieee_copy_sign_a10
module procedure ieee_copy_sign_a16
end interface ieee_copy_sign
! TODO: more interfaces (_fma, &c.)
private :: classify
contains
elemental logical function class_eq(x,y)
type(ieee_class_type), intent(in) :: x, y
class_eq = x%which == y%which
end function class_eq
elemental logical function class_ne(x,y)
type(ieee_class_type), intent(in) :: x, y
class_ne = x%which /= y%which
end function class_ne
elemental logical function round_eq(x,y)
type(ieee_round_type), intent(in) :: x, y
round_eq = x%mode == y%mode
end function round_eq
elemental logical function round_ne(x,y)
type(ieee_round_type), intent(in) :: x, y
round_ne = x%mode /= y%mode
end function round_ne
elemental type(ieee_class_type) function classify( &
expo,maxExpo,negative,significandNZ,quietBit)
integer, intent(in) :: expo, maxExpo
logical, intent(in) :: negative, significandNZ, quietBit
if (expo == 0) then
if (significandNZ) then
if (negative) then
classify = ieee_negative_denormal
else
classify = ieee_positive_denormal
end if
else
if (negative) then
classify = ieee_negative_zero
else
classify = ieee_positive_zero
end if
end if
else if (expo == maxExpo) then
if (significandNZ) then
if (quietBit) then
classify = ieee_quiet_nan
else
classify = ieee_signaling_nan
end if
else
if (negative) then
classify = ieee_negative_inf
else
classify = ieee_positive_inf
end if
end if
else
if (negative) then
classify = ieee_negative_normal
else
classify = ieee_positive_normal
end if
end if
end function classify
#define _CLASSIFY(RKIND,IKIND,TOTALBITS,PREC,IMPLICIT) \
type(ieee_class_type) elemental function ieee_class_a##RKIND(x); \
real(kind=RKIND), intent(in) :: x; \
integer(kind=IKIND) :: raw; \
integer, parameter :: significand = PREC - IMPLICIT; \
integer, parameter :: exponentBits = TOTALBITS - 1 - significand; \
integer, parameter :: maxExpo = shiftl(1, exponentBits) - 1; \
integer :: exponent, sign; \
logical :: negative, nzSignificand, quiet; \
raw = transfer(x, raw); \
exponent = ibits(raw, significand, exponentBits); \
negative = btest(raw, TOTALBITS - 1); \
nzSignificand = ibits(raw, 0, significand) /= 0; \
quiet = btest(raw, significand - 1); \
ieee_class_a##RKIND = classify(exponent, maxExpo, negative, nzSignificand, quiet); \
end function ieee_class_a##RKIND
_CLASSIFY(2,2,16,11,1)
_CLASSIFY(3,2,16,8,1)
_CLASSIFY(4,4,32,24,1)
_CLASSIFY(8,8,64,53,1)
_CLASSIFY(10,16,80,64,0)
_CLASSIFY(16,16,128,112,1)
#undef _CLASSIFY
! TODO: This might need to be an actual Operation instead
#define _COPYSIGN(RKIND,IKIND,BITS) \
real(kind=RKIND) elemental function ieee_copy_sign_a##RKIND(x,y); \
real(kind=RKIND), intent(in) :: x, y; \
integer(kind=IKIND) :: xbits, ybits; \
xbits = transfer(x, xbits); \
ybits = transfer(y, ybits); \
xbits = ior(ibclr(xbits, BITS-1), iand(ybits, shiftl(1_##IKIND, BITS-1))); \
ieee_copy_sign_a##RKIND = transfer(xbits, x); \
end function ieee_copy_sign_a##RKIND
_COPYSIGN(2,2,16)
_COPYSIGN(3,2,16)
_COPYSIGN(4,4,32)
_COPYSIGN(8,8,64)
_COPYSIGN(10,16,80)
_COPYSIGN(16,16,128)
#undef _COPYSIGN
end module ieee_arithmetic
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