popcnt(3I)

NAME
     _popcnt, POPCNT - Counts number of set bits

SYNOPSIS
     C/C++:

     #include <intrinsics.h>
     int _popcnt (long i);

     Fortran:

     POPCNT ([I=]i)

IMPLEMENTATION
     C/C++:  UNICOS and UNICOS/mk systems

     Fortran:  UNICOS, UNICOS/mk, and IRIX systems

STANDARDS
     C/C++:  Cray Research extension

     Fortran:  CF90 and MIPSpro 7 Fortran 90 compiler extension to Fortran
     90

C/C++ DESCRIPTION
     The _popcnt function returns the number of bits set to 1 (the
     population count) in argument i.

FORTRAN DESCRIPTION
     This intrinsic function counts the number of bits set in the argument.
     It accepts the following argument:

     i    A Boolean, integer, real, or Cray pointer value.  On IRIX
          systems, i cannot be declared as REAL(KIND=16).

     POPCNT is an elemental function.  The name of this intrinsic cannot be
     passed as an argument.

C/C++ NOTES
     Because _popcnt is an intrinsic function, no externally visible
     library function is available for it.  The compiler generates inline
     code to produce the result.

FORTRAN NOTES
     The bit representation of the logical data type is not consistent
     among Cray Research systems.  For further details, see your compiler's
     reference manuals.

FORTRAN RETURN VALUES
     POPCNT returns a value of type integer.

EXAMPLES
     Fortran: The following section of Fortran code shows the POPCNT
     function used with an argument of type integer.  The bit pattern of
     the argument and the value of the result are also given.  For
     simplicity, a 16-bit object is used.

          INTEGER I1, I2
          ...
          I2 = POPCNT(I1)


           ---------------------------------------------------------------
          | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 0 |
           ---------------------------------------------------------------
                                         I1

     The POPCNT function returns the value 6 to the integer variable I2.

SEE ALSO
     A complete list of C/C++ intrinsic functions available on Cray
     Research systems is in the Cray C/C++ Reference Manual, publication SR
     -2179.

     Intrinsic Procedures Reference Manual, publication SR-2138, for the
     printed version of this man page.