# BN_set_bit

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUES
HISTORY

## 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 ``` ``` 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)). 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).