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.\" ========================================================================
.\"
.IX Title "BN_ZERO 3"
.TH BN_ZERO 3 "2023-09-11" "1.1.1w" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
BN_zero, BN_one, BN_value_one, BN_set_word, BN_get_word \- BIGNUM assignment operations
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #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, BN_ULONG w);
\& unsigned BN_ULONG BN_get_word(BIGNUM *a);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fB\s-1BN_ULONG\s0\fR is a macro that will be an unsigned integral type optimized
for the most efficient implementation on the local platform.
.PP
\&\fBBN_zero()\fR, \fBBN_one()\fR and \fBBN_set_word()\fR set \fBa\fR to the values 0, 1 and
\&\fBw\fR respectively.  \fBBN_zero()\fR and \fBBN_one()\fR are macros.
.PP
\&\fBBN_value_one()\fR returns a \fB\s-1BIGNUM\s0\fR constant of value 1. This constant
is useful for use in comparisons and assignment.
.PP
\&\fBBN_get_word()\fR returns \fBa\fR, if it can be represented as a \fB\s-1BN_ULONG\s0\fR.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBBN_get_word()\fR returns the value \fBa\fR, or all-bits-set if \fBa\fR cannot
be represented as a single integer.
.PP
\&\fBBN_one()\fR and \fBBN_set_word()\fR return 1 on success, 0 otherwise.
\&\fBBN_value_one()\fR returns the constant.
\&\fBBN_zero()\fR never fails and returns no value.
.SH "BUGS"
.IX Header "BUGS"
If a \fB\s-1BIGNUM\s0\fR is equal to the value of all-bits-set, it will collide
with the error condition returned by \fBBN_get_word()\fR which uses that
as an error value.
.PP
\&\fB\s-1BN_ULONG\s0\fR should probably be a typedef.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBBN_bn2bin\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
In OpenSSL 0.9.8, \fBBN_zero()\fR was changed to not return a value; previous
versions returned an int.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2000\-2018 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.