BN_ZERO(3)                 Library Functions Manual                 BN_ZERO(3)

NAME
     BN_zero, BN_one, BN_value_one, BN_set_word, BN_get_word - BIGNUM
     assignment operations

SYNOPSIS
     #include <openssl/bn.h>

     int
     BN_zero(BIGNUM *a);

     int
     BN_one(BIGNUM *a);

     const BIGNUM *
     BN_value_one(void);

     int
     BN_set_word(BIGNUM *a, BN_ULONG w);

     BN_ULONG
     BN_get_word(const BIGNUM *a);

DESCRIPTION
     BN_ULONG is a macro that expands to an unsigned integral type optimized
     for the most efficient implementation on the local platform.  It is
     unsigned long (= uint64_t) on _LP64 platforms and unsigned int (=
     uint32_t) elsewhere.

     BN_zero(), BN_one(), and BN_set_word() set a to the values 0, 1 and w
     respectively.

     BN_value_one() returns a BIGNUM constant of value 1.  This constant is
     useful for comparisons and assignments.

RETURN VALUES
     BN_get_word() returns the value a, or a number with all bits set if a
     cannot be represented as a BN_ULONG.

     BN_zero(), BN_one(), and BN_set_word() return 1 on success, 0 otherwise.
     BN_value_one() returns the constant.

SEE ALSO
     BN_bn2bin(3), BN_new(3), BN_set_bit(3), BN_set_negative(3)

HISTORY
     BN_zero(), BN_one(), BN_value_one(), and BN_set_word() first appeared in
     SSLeay 0.5.1.  BN_get_word() first appeared in SSLeay 0.6.0.  These
     functions have been available since OpenBSD 2.4.

BUGS
     Someone might change the constant.

     If the value of a BIGNUM is equal to a BN_ULONG with all bits set, the
     return value of BN_get_word() collides with return value used to indicate
     errors.

     BN_ULONG should probably be a typedef rather than a macro.

Linux 6.8.7-arch1-1             April 30, 2023             Linux 6.8.7-arch1-1