BN_SET_BIT(3SSL) OpenSSL BN_SET_BIT(3SSL)
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 n is negative. An error is also returned if the internal
representation of a is already shorter than n bits. The internal
representation depends on the platform's word size, and this error can
be safely ignored. Use BN_num_bits(3) to determine the exact number of
bits if needed.
BN_lshift() shifts a left by n bits and places the result in r
("r=a*2^n"). Note that n must be nonnegative. 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 nonnegative. 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_num_bytes(3), BN_add(3)
COPYRIGHT
Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
3.5.7 2026-06-09 BN_SET_BIT(3SSL)
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