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/*
* Copyright (C) 2023, Google LLC
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.internal.storage.file;
/**
* A view of a byte[] as a list of integers stored in 3 bytes.
*
* The ints are stored in big-endian ("network order"), so
* byte[]{aa,bb,cc} becomes the int 0x00aabbcc
*/
final class UInt24Array {
public static final UInt24Array EMPTY = new UInt24Array(
new byte[0]);
private static final int ENTRY_SZ = 3;
private final byte[] data;
private final int size;
UInt24Array(byte[] data) {
this.data = data;
this.size = data.length / ENTRY_SZ;
}
boolean isEmpty() {
return size == 0;
}
int size() {
return size;
}
int get(int index) {
if (index < 0 || index >= size) {
throw new IndexOutOfBoundsException(index);
}
int offset = index * ENTRY_SZ;
int e = data[offset] & 0xff;
e <<= 8;
e |= data[offset + 1] & 0xff;
e <<= 8;
e |= data[offset + 2] & 0xff;
return e;
}
/**
* Search needle in the array.
*
* This assumes a sorted array.
*
* @param needle
* It cannot be bigger than 0xffffff (max unsigned three bytes).
* @return position of the needle in the array, -1 if not found. Runtime
* exception if the value is too big for 3 bytes.
*/
int binarySearch(int needle) {
if ((needle & 0xff000000) != 0) {
throw new IllegalArgumentException("Too big value for 3 bytes"); //$NON-NLS-1$
}
if (size == 0) {
return -1;
}
int high = size;
if (high == 0)
return -1;
int low = 0;
do {
int mid = (low + high) >>> 1;
int cmp;
cmp = Integer.compare(needle, get(mid));
if (cmp < 0)
high = mid;
else if (cmp == 0) {
return mid;
} else
low = mid + 1;
} while (low < high);
return -1;
}
int getLastValue() {
return get(size - 1);
}
}
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