Logical and Bit Manipulation Functions
======================================

   These functions behave as if two's complement arithmetic were used
(although sign-magnitude is used by the actual implementation).

 - Function: void mpz_and (mpz_t ROP, mpz_t OP1, mpz_t OP2)
     Set ROP to OP1 logical-and OP2.

 - Function: void mpz_ior (mpz_t ROP, mpz_t OP1, mpz_t OP2)
     Set ROP to OP1 inclusive-or OP2.

 - Function: void mpz_com (mpz_t ROP, mpz_t OP)
     Set ROP to the one's complement of OP.

 - Function: unsigned long int mpz_popcount (mpz_t OP)
     For non-negative numbers, return the population count of OP.  For
     negative numbers, return the largest possible value (MAX_ULONG).

 - Function: unsigned long int mpz_hamdist (mpz_t OP1, mpz_t OP2)
     If OP1 and OP2 are both non-negative, return the hamming distance
     between the two operands.  Otherwise, return the largest possible
     value (MAX_ULONG).

     It is possible to extend this function to return a useful value
     when the operands are both negative, but the current
     implementation returns MAX_ULONG in this case.  *Do not depend on
     this behavior, since it will change in future versions of the
     library.*

 - Function: unsigned long int mpz_scan0 (mpz_t OP, unsigned long int
          STARTING_BIT)
     Scan OP, starting with bit STARTING_BIT, towards more significant
     bits, until the first clear bit is found.  Return the index of the
     found bit.

 - Function: unsigned long int mpz_scan1 (mpz_t OP, unsigned long int
          STARTING_BIT)
     Scan OP, starting with bit STARTING_BIT, towards more significant
     bits, until the first set bit is found.  Return the index of the
     found bit.

 - Function: void mpz_setbit (mpz_t ROP, unsigned long int BIT_INDEX)
     Set bit BIT_INDEX in OP1.

 - Function: void mpz_clrbit (mpz_t ROP, unsigned long int BIT_INDEX)
     Clear bit BIT_INDEX in OP1.