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.Dd $Mdocdate: July 5 2016 $
.Dt BN_ADD_WORD 3
.Os
.Sh NAME
.Nm BN_add_word ,
.Nm BN_sub_word ,
.Nm BN_mul_word ,
.Nm BN_div_word ,
.Nm BN_mod_word
.Nd arithmetic functions on BIGNUMs with integers
.Sh SYNOPSIS
.In openssl/bn.h
.Ft int
.Fo BN_add_word
.Fa "BIGNUM *a"
.Fa "BN_ULONG w"
.Fc
.Ft int
.Fo BN_sub_word
.Fa "BIGNUM *a"
.Fa "BN_ULONG w"
.Fc
.Ft int
.Fo BN_mul_word
.Fa "BIGNUM *a"
.Fa "BN_ULONG w"
.Fc
.Ft BN_ULONG
.Fo BN_div_word
.Fa "BIGNUM *a"
.Fa "BN_ULONG w"
.Fc
.Ft BN_ULONG
.Fo BN_mod_word
.Fa "const BIGNUM *a"
.Fa "BN_ULONG w"
.Fc
.Sh DESCRIPTION
These functions perform arithmetic operations on BIGNUMs with unsigned
integers.
They are much more efficient than the normal BIGNUM arithmetic
operations.
.Pp
.Fn BN_add_word
adds
.Fa w
to
.Fa a
.Pq Li a+=w .
.Pp
.Fn BN_sub_word
subtracts
.Fa w
from
.Fa a
.Pq Li a-=w .
.Pp
.Fn BN_mul_word
multiplies
.Fa a
and
.Fa w
.Pq Li a*=w .
.Pp
.Fn BN_div_word
divides
.Fa a
by
.Fa w
.Pq Li a/=w
and returns the remainder.
.Pp
.Fn BN_mod_word
returns the remainder of
.Fa a
divided by
.Fa w
.Pq Li a%w
or (BN_ULONG)-1 on error.
.Pp
For
.Fn BN_div_word
and
.Fn BN_mod_word ,
.Fa w
must not be 0.
.Sh RETURN VALUES
.Fn BN_add_word ,
.Fn BN_sub_word ,
and
.Fn BN_mul_word
return 1 for success, 0 on error.
The error codes can be obtained by
.Xr ERR_get_error 3 .
.Pp
.Fn BN_mod_word
and
.Fn BN_div_word
return
.Fa a Ns % Ns Fa w
on success and
.Pq Vt BN_ULONG Ns -1
if an error occurred.
.Sh SEE ALSO
.Xr bn 3 ,
.Xr BN_add 3 ,
.Xr ERR_get_error 3
.Sh HISTORY
.Fn BN_add_word
and
.Fn BN_mod_word
are available in all versions of SSLeay and OpenSSL.
.Fn BN_div_word
was added in SSLeay 0.8, and
.Fn BN_sub_word
and
.Fn BN_mul_word
in SSLeay 0.9.0.
.Pp
Before 0.9.8a, the return value for
.Fn BN_div_word
and
.Fn BN_mod_word
in case of an error was 0.
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