1*2175Sjp161948=pod 2*2175Sjp161948 3*2175Sjp161948=head1 NAME 4*2175Sjp161948 5*2175Sjp161948BN_set_bit, BN_clear_bit, BN_is_bit_set, BN_mask_bits, BN_lshift, 6*2175Sjp161948BN_lshift1, BN_rshift, BN_rshift1 - bit operations on BIGNUMs 7*2175Sjp161948 8*2175Sjp161948=head1 SYNOPSIS 9*2175Sjp161948 10*2175Sjp161948 #include <openssl/bn.h> 11*2175Sjp161948 12*2175Sjp161948 int BN_set_bit(BIGNUM *a, int n); 13*2175Sjp161948 int BN_clear_bit(BIGNUM *a, int n); 14*2175Sjp161948 15*2175Sjp161948 int BN_is_bit_set(const BIGNUM *a, int n); 16*2175Sjp161948 17*2175Sjp161948 int BN_mask_bits(BIGNUM *a, int n); 18*2175Sjp161948 19*2175Sjp161948 int BN_lshift(BIGNUM *r, const BIGNUM *a, int n); 20*2175Sjp161948 int BN_lshift1(BIGNUM *r, BIGNUM *a); 21*2175Sjp161948 22*2175Sjp161948 int BN_rshift(BIGNUM *r, BIGNUM *a, int n); 23*2175Sjp161948 int BN_rshift1(BIGNUM *r, BIGNUM *a); 24*2175Sjp161948 25*2175Sjp161948=head1 DESCRIPTION 26*2175Sjp161948 27*2175Sjp161948BN_set_bit() sets bit B<n> in B<a> to 1 (C<a|=(1E<lt>E<lt>n)>). The 28*2175Sjp161948number is expanded if necessary. 29*2175Sjp161948 30*2175Sjp161948BN_clear_bit() sets bit B<n> in B<a> to 0 (C<a&=~(1E<lt>E<lt>n)>). An 31*2175Sjp161948error occurs if B<a> is shorter than B<n> bits. 32*2175Sjp161948 33*2175Sjp161948BN_is_bit_set() tests if bit B<n> in B<a> is set. 34*2175Sjp161948 35*2175Sjp161948BN_mask_bits() truncates B<a> to an B<n> bit number 36*2175Sjp161948(C<a&=~((~0)E<gt>E<gt>n)>). An error occurs if B<a> already is 37*2175Sjp161948shorter than B<n> bits. 38*2175Sjp161948 39*2175Sjp161948BN_lshift() shifts B<a> left by B<n> bits and places the result in 40*2175Sjp161948B<r> (C<r=a*2^n>). BN_lshift1() shifts B<a> left by one and places 41*2175Sjp161948the result in B<r> (C<r=2*a>). 42*2175Sjp161948 43*2175Sjp161948BN_rshift() shifts B<a> right by B<n> bits and places the result in 44*2175Sjp161948B<r> (C<r=a/2^n>). BN_rshift1() shifts B<a> right by one and places 45*2175Sjp161948the result in B<r> (C<r=a/2>). 46*2175Sjp161948 47*2175Sjp161948For the shift functions, B<r> and B<a> may be the same variable. 48*2175Sjp161948 49*2175Sjp161948=head1 RETURN VALUES 50*2175Sjp161948 51*2175Sjp161948BN_is_bit_set() returns 1 if the bit is set, 0 otherwise. 52*2175Sjp161948 53*2175Sjp161948All other functions return 1 for success, 0 on error. The error codes 54*2175Sjp161948can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>. 55*2175Sjp161948 56*2175Sjp161948=head1 SEE ALSO 57*2175Sjp161948 58*2175Sjp161948L<bn(3)|bn(3)>, L<BN_num_bytes(3)|BN_num_bytes(3)>, L<BN_add(3)|BN_add(3)> 59*2175Sjp161948 60*2175Sjp161948=head1 HISTORY 61*2175Sjp161948 62*2175Sjp161948BN_set_bit(), BN_clear_bit(), BN_is_bit_set(), BN_mask_bits(), 63*2175Sjp161948BN_lshift(), BN_lshift1(), BN_rshift(), and BN_rshift1() are available 64*2175Sjp161948in all versions of SSLeay and OpenSSL. 65*2175Sjp161948 66*2175Sjp161948=cut 67