mirror of
https://github.com/openssl/openssl.git
synced 2024-12-09 05:51:54 +08:00
b6ef3c7089
CLA: trivial Correct right shift to left shift. Pseudo code `a&=~((~0)>>n)` means "get higher n-bits of a", but actually crypto lib gives lower n-bits. Reviewed-by: Matt Caswell <matt@openssl.org> Reviewed-by: Paul Dale <paul.dale@oracle.com> (Merged from https://github.com/openssl/openssl/pull/12727)
70 lines
2.0 KiB
Plaintext
70 lines
2.0 KiB
Plaintext
=pod
|
|
|
|
=head1 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
|
|
|
|
=head1 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);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
BN_set_bit() sets bit B<n> in B<a> to 1 (C<a|=(1E<lt>E<lt>n)>). The
|
|
number is expanded if necessary.
|
|
|
|
BN_clear_bit() sets bit B<n> in B<a> to 0 (C<a&=~(1E<lt>E<lt>n)>). An
|
|
error occurs if B<a> is shorter than B<n> bits.
|
|
|
|
BN_is_bit_set() tests if bit B<n> in B<a> is set.
|
|
|
|
BN_mask_bits() truncates B<a> to an B<n> bit number
|
|
(C<a&=~((~0)E<lt>E<lt>n)>). An error occurs if B<a> already is
|
|
shorter than B<n> bits.
|
|
|
|
BN_lshift() shifts B<a> left by B<n> bits and places the result in
|
|
B<r> (C<r=a*2^n>). Note that B<n> must be nonnegative. BN_lshift1() shifts
|
|
B<a> left by one and places the result in B<r> (C<r=2*a>).
|
|
|
|
BN_rshift() shifts B<a> right by B<n> bits and places the result in
|
|
B<r> (C<r=a/2^n>). Note that B<n> must be nonnegative. BN_rshift1() shifts
|
|
B<a> right by one and places the result in B<r> (C<r=a/2>).
|
|
|
|
For the shift functions, B<r> and B<a> may be the same variable.
|
|
|
|
=head1 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 L<ERR_get_error(3)>.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<BN_num_bytes(3)>, L<BN_add(3)>
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2000-2020 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
|
|
L<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|