rdieee.F90

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subroutine rdieee(rieee,a,num)
  implicit none
  
  real(4), intent(in) :: rieee(num)
  real, intent(out) :: a(num)
  integer, intent(in) :: num
 
  integer(4) :: ieee
  real, parameter :: two23 = scale(1.0,-23)
  real, parameter :: two126 = scale(1.0,-126)
  integer :: iexp, imant, isign, j
  real :: sign, temp
 
  do j = 1, num
     ! Transfer IEEE bit string to integer variable.
     ieee = transfer(rieee(j), ieee)
 
     ! Extract sign bit, exponent, and mantissa.
     isign = ibits(ieee, 31, 1)
     iexp = ibits(ieee, 23, 8)
     imant = ibits(ieee, 0, 23)
     sign = 1.0
     if (isign .eq. 1) sign = -1.0
 
     if (iexp .gt. 0 .and. iexp .lt. 255) then
        temp = 2.0**(iexp - 127)
        a(j) = sign * temp * (1.0 + (two23 * real(imant)))
     elseif (iexp .eq. 0) then
        if (imant .ne. 0) then
           a(j) = sign * two126 * two23 * real(imant)
        else
           a(j) = sign * 0.0
        endif
     elseif (iexp .eq. 255) then
        a(j) = sign * huge(a(j))
     endif
  enddo
end subroutine rdieee