int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
                       int prediction_resistance,
                       const unsigned char *adin, size_t adinlen)
{
    if (drbg->state == DRBG_ERROR) {
        RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
        return 0;
    }
    if (drbg->state == DRBG_UNINITIALISED) {
        RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
        return 0;
    }
    if (outlen > drbg->max_request) {
        RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
        return 0;
    }
    if (adinlen > drbg->max_adin) {
        RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
        return 0;
    }

    if (drbg->reseed_counter >= drbg->reseed_interval)
        drbg->state = DRBG_RESEED;

    if (drbg->state == DRBG_RESEED || prediction_resistance) {
        if (!RAND_DRBG_reseed(drbg, adin, adinlen)) {
            RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
            return 0;
        }
        adin = NULL;
        adinlen = 0;
    }

    if (!ctr_generate(drbg, out, outlen, adin, adinlen)) {
        drbg->state = DRBG_ERROR;
        RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
        return 0;
    }

    if (drbg->reseed_counter >= drbg->reseed_interval)
        drbg->state = DRBG_RESEED;
    else
        drbg->reseed_counter++;
    return 1;
}