libressl-BN_set_bit3
Bit operations on bignums
Usage
Crypto Library (libcrypto, -lcrypto)
#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);
Overview
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).