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/*
* Copyright (C) 2011 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package benchmarks.regression;
import com.google.caliper.Param;
import com.google.caliper.SimpleBenchmark;
public class IntegerBenchmark extends SimpleBenchmark {
public int timeLongSignumBranch(int reps) {
int t = 0;
for (int i = 0; i < reps; ++i) {
t += signum1(-i);
t += signum1(0);
t += signum1(i);
}
return t;
}
public int timeLongSignumBranchFree(int reps) {
int t = 0;
for (int i = 0; i < reps; ++i) {
t += signum2(-i);
t += signum2(0);
t += signum2(i);
}
return t;
}
private static int signum1(long v) {
return v < 0 ? -1 : (v == 0 ? 0 : 1);
}
private static int signum2(long v) {
return ((int)(v >> 63)) | (int) (-v >>> 63); // Hacker's delight 2-7
}
public int timeLongBitCount_BitSet(int reps) {
int t = 0;
for (int i = 0; i < reps; ++i) {
t += pop((long) i);
}
return t;
}
private static int pop(long l) {
int count = popX(l & 0xffffffffL);
count += popX(l >>> 32);
return count;
}
private static int popX(long x) {
// BEGIN android-note
// delegate to Integer.bitCount(i); consider using native code
// END android-note
x = x - ((x >>> 1) & 0x55555555);
x = (x & 0x33333333) + ((x >>> 2) & 0x33333333);
x = (x + (x >>> 4)) & 0x0f0f0f0f;
x = x + (x >>> 8);
x = x + (x >>> 16);
return (int) x & 0x0000003f;
}
public int timeLongBitCount_2Int(int reps) {
int t = 0;
for (int i = 0; i < reps; ++i) {
t += pop2((long) i);
}
return t;
}
private static int pop2(long l) {
int count = Integer.bitCount((int) (l & 0xffffffffL));
count += Integer.bitCount((int) (l >>> 32));
return count;
}
public int timeLongBitCount_Long(int reps) {
int t = 0;
for (int i = 0; i < reps; ++i) {
t += Long.bitCount((long) i);
}
return t;
}
/**
* Table for Seal's algorithm for Number of Trailing Zeros. Hacker's Delight
* online, Figure 5-18 (http://www.hackersdelight.org/revisions.pdf)
* The entries whose value is -1 are never referenced.
*/
private static final byte[] NTZ_TABLE = {
32, 0, 1, 12, 2, 6, -1, 13, 3, -1, 7, -1, -1, -1, -1, 14,
10, 4, -1, -1, 8, -1, -1, 25, -1, -1, -1, -1, -1, 21, 27, 15,
31, 11, 5, -1, -1, -1, -1, -1, 9, -1, -1, 24, -1, -1, 20, 26,
30, -1, -1, -1, -1, 23, -1, 19, 29, -1, 22, 18, 28, 17, 16, -1
};
private static int numberOfTrailingZerosHD(int i) {
// Seal's algorithm - Hacker's Delight 5-18
i &= -i;
i = (i << 4) + i; // x *= 17
i = (i << 6) + i; // x *= 65
i = (i << 16) - i; // x *= 65535
return NTZ_TABLE[i >>> 26];
}
private static int numberOfTrailingZerosOL(int i) {
return NTZ_TABLE[((i & -i) * 0x0450FBAF) >>> 26];
}
public int timeNumberOfTrailingZerosHD(int reps) {
int t = 0;
for (int i = 0; i < reps; ++i) {
t += numberOfTrailingZerosHD(i);
}
return t;
}
public int timeNumberOfTrailingZerosOL(int reps) {
int t = 0;
for (int i = 0; i < reps; ++i) {
t += numberOfTrailingZerosOL(i);
}
return t;
}
}
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