BN_SET_BIT(3)              Library Functions Manual              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, const BIGNUM *a);

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

     int
     BN_rshift1(BIGNUM *r, const 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).
     Note that n must be non-negative.  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).  Note that n must be non-negative.  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_add(3), BN_new(3), BN_num_bytes(3), BN_set_negative(3), BN_zero(3)

HISTORY
     BN_set_bit(), BN_clear_bit(), BN_is_bit_set(), BN_mask_bits(),
     BN_lshift(), BN_lshift1(), BN_rshift(), and BN_rshift1() first appeared
     in SSLeay 0.5.1 and have been available since OpenBSD 2.4.

Linux 6.8.2-arch2-1            November 30, 2021           Linux 6.8.2-arch2-1