OpenSSL::BN.new

static VALUE
ossl_bn_initialize(int argc, VALUE *argv, VALUE self)
{
    BIGNUM *bn;
    VALUE str, bs;
    int base = 10;
    char *ptr;

    if (rb_scan_args(argc, argv, "11", &str, &bs) == 2) {
        base = NUM2INT(bs);
    }

    if (NIL_P(str)) {
        ossl_raise(rb_eArgError, "invalid argument");
    }

    rb_check_frozen(self);
    if (RB_INTEGER_TYPE_P(str)) {
        GetBN(self, bn);
        integer_to_bnptr(str, bn);

        return self;
    }

    if (RTEST(rb_obj_is_kind_of(str, cBN))) {
        BIGNUM *other;

        GetBN(self, bn);
        GetBN(str, other); /* Safe - we checked kind_of? above */
        if (!BN_copy(bn, other)) {
            ossl_raise(eBNError, NULL);
        }
        return self;
    }

    GetBN(self, bn);
    switch (base) {
      case 0:
        ptr = StringValuePtr(str);
        if (!BN_mpi2bn((unsigned char *)ptr, RSTRING_LENINT(str), bn)) {
            ossl_raise(eBNError, NULL);
        }
        break;
      case 2:
        ptr = StringValuePtr(str);
        if (!BN_bin2bn((unsigned char *)ptr, RSTRING_LENINT(str), bn)) {
            ossl_raise(eBNError, NULL);
        }
        break;
      case 10:
        if (!BN_dec2bn(&bn, StringValueCStr(str))) {
            ossl_raise(eBNError, NULL);
        }
        break;
      case 16:
        if (!BN_hex2bn(&bn, StringValueCStr(str))) {
            ossl_raise(eBNError, NULL);
        }
        break;
      default:
        ossl_raise(rb_eArgError, "invalid radix %d", base);
    }
    return self;
}