1 /*
2 * This file is part of Waarp Project (named also Waarp or GG).
3 *
4 * Copyright (c) 2019, Waarp SAS, and individual contributors by the @author
5 * tags. See the COPYRIGHT.txt in the distribution for a full listing of
6 * individual contributors.
7 *
8 * All Waarp Project is free software: you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation, either version 3 of the License, or (at your
11 * option) any later version.
12 *
13 * Waarp is distributed in the hope that it will be useful, but WITHOUT ANY
14 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
15 * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License along with
18 * Waarp . If not, see <http://www.gnu.org/licenses/>.
19 */
20
21 /*
22 * Licensed under the Apache License, Version 2.0 (the "License");
23 * you may not use this file except in compliance with the License.
24 * You may obtain a copy of the License at
25 *
26 * http://www.apache.org/licenses/LICENSE-2.0
27 *
28 * Unless required by applicable law or agreed to in writing, software
29 * distributed under the License is distributed on an "AS IS" BASIS,
30 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
31 * See the License for the specific language governing permissions and
32 * limitations under the License.
33 */
34 package org.waarp.compress.zstdunsafe;
35
36 import java.util.Arrays;
37
38 class Histogram {
39 private Histogram() {
40 }
41
42 // TODO: _count parallel heuristic for large inputs
43 private static void _count(final Object inputBase, final int inputSize,
44 final int[] counts) {
45 long input = sun.misc.Unsafe.ARRAY_BYTE_BASE_OFFSET;
46
47 Arrays.fill(counts, 0);
48
49 for (int i = 0; i < inputSize; i++) {
50 final int symbol = UnsafeUtil.UNSAFE.getByte(inputBase, input) & 0xFF;
51 input++;
52 counts[symbol]++;
53 }
54 }
55
56 public static int findLargestCount(final int[] counts, final int maxSymbol) {
57 int max = 0;
58 for (int i = 0; i <= maxSymbol; i++) {
59 if (counts[i] > max) {
60 max = counts[i];
61 }
62 }
63
64 return max;
65 }
66
67 public static int findMaxSymbol(final int[] counts, int maxSymbol) {
68 while (counts[maxSymbol] == 0) {
69 maxSymbol--;
70 }
71 return maxSymbol;
72 }
73
74 public static void count(final byte[] input, final int length,
75 final int[] counts) {
76 _count(input, length, counts);
77 }
78 }