/*
 * Simple random number generator for testing.
 * Copyright © 2022-2024 Nick Bowler
 *
 * Directly compare the test lib RNG against the reference implementation.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <config.h>
#include "tap.h"

#if !HAVE_FOR_DECLS
int main(void)
{
	tap_skip_all("cannot compile reference xoshiro256+");
}
#else
#define TEST_RNG_NO_EXTERNAL_API 1
#include "rng.c"
#include "xos256p.c"

int main(void)
{
	unsigned long long test_result, ref_result;
	unsigned long long ref_state[4], test_state[4];
	uint_least32_t seed_state = 0xdeadbeef;
	int i, ret = 0;

	tap_plan(200);
	for (i = 0; i < 100; i++) {
		s[0] = ref_state[0] = test_state[0] = seed64(&seed_state);
		s[1] = ref_state[1] = test_state[1] = seed64(&seed_state);
		s[2] = ref_state[2] = test_state[2] = seed64(&seed_state);
		s[3] = ref_state[3] = test_state[3] = seed64(&seed_state);

		ref_result = next();
		test_result = xoshiro256p(test_state);

		if (!tap_result(ref_result == test_result, "rng output")) {
			tap_diag("Failed, unexpected result");
			tap_diag("   with initial state %llx %llx %llx %llx",
			                          ref_state[0], ref_state[1],
			                          ref_state[2], ref_state[3]);
			tap_diag("   received: %llx", test_result);
			tap_diag("   expected: %llx", ref_result);
		}

		if (!tap_result(s[0] == test_state[0] && s[1] == test_state[1]
		             && s[2] == test_state[2] && s[3] == test_state[3],
		                "rng state update"))
		{
			tap_diag("Failed, state update differed");
			tap_diag("   with initial state %llx %llx %llx %llx",
			                          ref_state[0], ref_state[1],
			                          ref_state[2], ref_state[3]);
			tap_diag("   received: %llx %llx %llx %llx",
			               test_state[0], test_state[1],
			               test_state[2], test_state[3]);
			tap_diag("   expected: %llx %llx %llx %llx",
			               (unsigned long long)s[0],
			               (unsigned long long)s[1],
			               (unsigned long long)s[2],
			               (unsigned long long)s[3]);
		}
	}

	tap_done();
}
#endif