.\" $OpenBSD: BN_cmp.3,v 1.10 2022/11/22 19:02:07 schwarze Exp $
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.\" This file was written by Ulf Moeller <ulf@openssl.org>.
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.Dd $Mdocdate: November 22 2022 $
.Dt BN_CMP 3
.Os
.Sh NAME
.Nm BN_cmp ,
.Nm BN_ucmp ,
.Nm BN_is_zero ,
.Nm BN_is_one ,
.Nm BN_is_word ,
.Nm BN_abs_is_word ,
.Nm BN_is_odd
.Nd BIGNUM comparison and test functions
.Sh SYNOPSIS
.In openssl/bn.h
.Ft int
.Fo BN_cmp
.Fa "const BIGNUM *a"
.Fa "const BIGNUM *b"
.Fc
.Ft int
.Fo BN_ucmp
.Fa "const BIGNUM *a"
.Fa "const BIGNUM *b"
.Fc
.Ft int
.Fo BN_is_zero
.Fa "const BIGNUM *a"
.Fc
.Ft int
.Fo BN_is_one
.Fa "const BIGNUM *a"
.Fc
.Ft int
.Fo BN_is_word
.Fa "const BIGNUM *a"
.Fa "const BN_ULONG w"
.Fc
.Ft int
.Fo BN_abs_is_word
.Fa "const BIGNUM *a"
.Fa "const BN_ULONG w"
.Fc
.Ft int
.Fo BN_is_odd
.Fa "const BIGNUM *a"
.Fc
.Sh DESCRIPTION
.Fn BN_cmp
compares the numbers
.Fa a
and
.Fa b .
.Fn BN_ucmp
compares their absolute values.
.Pp
.Fn BN_is_zero ,
.Fn BN_is_one
and
.Fn BN_is_word
test if
.Fa a
equals 0, 1, or
.Fa w
respectively.
.Fn BN_abs_is_word
tests if the absolute value of
.Fa a
equals
.Fa w .
.Fn BN_is_odd
tests if a is odd.
.Pp
.Vt BN_ULONG
is a macro that expands to
.Vt unsigned long Pq = Vt uint64_t
on
.Dv _LP64
platforms and
.Vt unsigned int Pq = Vt uint32_t
elsewhere.
.Sh RETURN VALUES
.Fn BN_cmp
returns -1 if
.Fa a Ns < Ns Fa b ,
0 if
.Fa a Ns == Ns Fa b ,
and 1 if
.Fa a Ns > Ns Fa b .
.Fn BN_ucmp
is the same using the absolute values of
.Fa a
and
.Fa b .
.Pp
.Fn BN_is_zero ,
.Fn BN_is_one ,
.Fn BN_is_word ,
.Fn BN_abs_is_word ,
and
.Fn BN_is_odd
return 1 if the condition is true, 0 otherwise.
.Sh SEE ALSO
.Xr BN_new 3
.Sh HISTORY
.Fn BN_cmp ,
.Fn BN_ucmp ,
.Fn BN_is_zero ,
.Fn BN_is_one ,
and
.Fn BN_is_word
first appeared in SSLeay 0.5.1.
.Fn BN_is_odd
first appeared in SSLeay 0.8.0.
These functions have been available since
.Ox 2.4 .
.Pp
.Fn BN_abs_is_word
first appeared in OpenSSL 0.9.7 and has been available since
.Ox 3.2 .