openssl/doc/crypto/BN_zero.pod
Viktor Dukhovni 98186eb4e4 Backwards-compatibility subject to OPENSSL_API_COMPAT
Provide backwards-compatiblity for functions, macros and include
files if OPENSSL_API_COMPAT is either not defined or defined less
than the version number of the release in which the feature was
deprecated.

Reviewed-by: Richard Levitte <levitte@openssl.org>
2016-01-07 20:53:18 -05:00

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=pod
=head1 NAME
BN_zero, BN_one, BN_value_one, BN_set_word, BN_get_word - BIGNUM assignment
operations
=head1 SYNOPSIS
#include <openssl/bn.h>
void BN_zero(BIGNUM *a);
int BN_one(BIGNUM *a);
const BIGNUM *BN_value_one(void);
int BN_set_word(BIGNUM *a, unsigned long w);
unsigned long BN_get_word(BIGNUM *a);
Deprecated:
#if OPENSSL_API_COMPAT < 0x00908000L
int BN_zero(BIGNUM *a);
#endif
=head1 DESCRIPTION
BN_zero(), BN_one() and BN_set_word() set B<a> to the values 0, 1 and
B<w> respectively. BN_zero() and BN_one() are macros.
BN_value_one() returns a B<BIGNUM> constant of value 1. This constant
is useful for use in comparisons and assignment.
BN_get_word() returns B<a>, if it can be represented as an unsigned
long.
=head1 RETURN VALUES
BN_get_word() returns the value B<a>, and 0xffffffffL if B<a> cannot
be represented as an unsigned long.
BN_one(), BN_set_word() and the deprecated version of BN_zero()
return 1 on success, 0 otherwise.
BN_value_one() returns the constant.
The preferred version of BN_zer() never fails and returns no value.
=head1 BUGS
Someone might change the constant.
If a B<BIGNUM> is equal to 0xffffffffL it can be represented as an
unsigned long but this value is also returned on error.
=head1 SEE ALSO
L<bn(3)>, L<BN_bn2bin(3)>
=cut