ISHA (integer, shift)

  Class:  Elemental function - Generic

  Arithmetically shifts an integer left or right by a specified
  number of bits.

  The "shift" is of type integer; it is the direction and distance of
  shift.

  The result type is the same as "integer".

  If "shift" is positive, the shift is to the left; if "shift" is
  negative, the shift is to the right.  If "shift" is zero, no shift
  is performed.

  Bits shifted out from the left or from the right, as appropriate,
  are lost.  If the shift is to the left, zeros are shifted in on the
  right.  If the shift is to the right, copies of the sign bit (0 for
  non-negative "integer"; 1 for negative "integer") are shifted in on
  the left.

  The kind of integer is important in arithmetic shifting because
  sign varies among integer representations (see the following
  example).  If you want to shift a one-byte or two-byte argument,
  you must declare it as INTEGER(1) or INTEGER(2).

  Examples:

  Consider the following:

    INTEGER(1) i, res1
    INTEGER(2) j, res2
    i = -128             ! equal to  10000000
    j = -32768           ! equal to  10000000 00000000
    res1  = ISHA (i, -4) ! returns 11111000 = -8
    res2  = ISHA (j, -4) ! returns 11111000 00000000 = -2048