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package it.unimi.dsi.fastutil;

import static org.junit.Assert.assertTrue;
import static org.junit.Assert.assertEquals;

import org.junit.Test;

public class HashCommonTest {
	@Test
	public void testMaxFillSmall() {
		for(float f: new float[] { 0.0001f, .25f, .50f, .75f, .9999f }) {
			for(int i = 0; i < 16; i++) {
				final int n = HashCommon.arraySize(i, f);
				final int maxFill = HashCommon.maxFill(n, f);
				assertTrue(n + " <= " + maxFill, n > maxFill);
			}

			for(long i = 0; i < 16; i++) {
				final long n = HashCommon.bigArraySize(i, f);
				final long maxFill = HashCommon.maxFill(n, f);
				assertTrue(n + " <= " + maxFill, n > maxFill);
			}
		}
	}

	@Test
	public void testInverses() {
		for(int i = 0 ; i < 1 << 30; i += 10000) {
			assertEquals(i, HashCommon.invMix(HashCommon.mix(i)));
			assertEquals(i, HashCommon.mix(HashCommon.invMix(i)));
		}
		for(long i = 0 ; i < 1 << 62; i += 1000000) {
			assertEquals(i, HashCommon.invMix(HashCommon.mix(i)));
			assertEquals(i, HashCommon.mix(HashCommon.invMix(i)));
		}
	}
}