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.