new

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

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

    if (RB_TYPE_P(str, T_FIXNUM)) {
        long i;
        unsigned char bin[sizeof(long)];
        long n = FIX2LONG(str);
        unsigned long un = labs(n);

        for (i = sizeof(long) - 1; 0 <= i; i--) {
            bin[i] = un&0xff;
            un >>= 8;
        }

        GetBN(self, bn);
        if (!BN_bin2bn(bin, sizeof(bin), bn)) {
            ossl_raise(eBNError, NULL);
        }
        if (n < 0) BN_set_negative(bn, 1);
        return self;
    }
    else if (RB_TYPE_P(str, T_BIGNUM)) {
        size_t len = rb_absint_size(str, NULL);
        unsigned char *bin;
        VALUE buf;
        int sign;

        if (INT_MAX < len) {
            rb_raise(eBNError, "bignum too long");
        }
        bin = (unsigned char*)ALLOCV_N(unsigned char, buf, len);
        sign = rb_integer_pack(str, bin, len, 1, 0, INTEGER_PACK_BIG_ENDIAN);

        GetBN(self, bn);
        if (!BN_bin2bn(bin, (int)len, bn)) {
            ALLOCV_END(buf);
            ossl_raise(eBNError, NULL);
        }
        ALLOCV_END(buf);
        if (sign < 0) BN_set_negative(bn, 1);
        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;
    }

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