BN_set_bit(3)

     NAME
          BN_set_bit, BN_clear_bit, BN_is_bit_set, BN_mask_bits,
          BN_lshift, BN_lshift1, BN_rshift, BN_rshift1 - bit
          operations on BIGNUMs

     SYNOPSIS
           #include <openssl/bn.h>

           int BN_set_bit(BIGNUM *a, int n);
           int BN_clear_bit(BIGNUM *a, int n);

           int BN_is_bit_set(const BIGNUM *a, int n);

           int BN_mask_bits(BIGNUM *a, int n);

           int BN_lshift(BIGNUM *r, const BIGNUM *a, int n);
           int BN_lshift1(BIGNUM *r, BIGNUM *a);

           int BN_rshift(BIGNUM *r, BIGNUM *a, int n);
           int BN_rshift1(BIGNUM *r, BIGNUM *a);


     DESCRIPTION
          BN_set_bit() sets bit n in a to 1 (a|=(1<<n)). The number is
          expanded if necessary.

          BN_clear_bit() sets bit n in a to 0 (a&=~(1<<n)). An error
          occurs if a is shorter than n bits.

          BN_is_bit_set() tests if bit n in a is set.

          BN_mask_bits() truncates a to an n bit number
          (a&=~((~0)>>n)).  An error occurs if a already is shorter
          than n bits.

          BN_lshift() shifts a left by n bits and places the result in
          r (r=a*2^n). BN_lshift1() shifts a left by one and places
          the result in r (r=2*a).

          BN_rshift() shifts a right by n bits and places the result
          in r (r=a/2^n). BN_rshift1() shifts a right by one and
          places the result in r (r=a/2).

          For the shift functions, r and a may be the same variable.

     RETURN VALUES
          BN_is_bit_set() returns 1 if the bit is set, 0 otherwise.

          All other functions return 1 for success, 0 on error. The
          error codes can be obtained by ERR_get_error(3).

     SEE ALSO
          bn(3), BN_num_bytes(3), BN_add(3)

     HISTORY
          BN_set_bit(), BN_clear_bit(), BN_is_bit_set(),
          BN_mask_bits(), BN_lshift(), BN_lshift1(), BN_rshift(), and
          BN_rshift1() are available in all versions of SSLeay and
          OpenSSL.