/*******************************************************************************
* Copyright 2011 See AUTHORS file.
*
* 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 com.badlogic.gdx.utils;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
/** Extends {@link DataInputStream} with additional convenience methods.
* @author Nathan Sweet */
public class DataInput extends DataInputStream {
private char[] chars = new char[32];
public DataInput (InputStream in) {
super(in);
}
/** Reads a 1-5 byte int. */
public int readInt (boolean optimizePositive) throws IOException {
int b = read();
int result = b & 0x7F;
if ((b & 0x80) != 0) {
b = read();
result |= (b & 0x7F) << 7;
if ((b & 0x80) != 0) {
b = read();
result |= (b & 0x7F) << 14;
if ((b & 0x80) != 0) {
b = read();
result |= (b & 0x7F) << 21;
if ((b & 0x80) != 0) {
b = read();
result |= (b & 0x7F) << 28;
}
}
}
}
return optimizePositive ? result : ((result >>> 1) ^ -(result & 1));
}
/** Reads the length and string of UTF8 characters, or null.
* @return May be null. */
public String readString () throws IOException {
int charCount = readInt(true);
switch (charCount) {
case 0:
return null;
case 1:
return "";
}
charCount--;
if (chars.length < charCount) chars = new char[charCount];
char[] chars = this.chars;
// Try to read 7 bit ASCII chars.
int charIndex = 0;
int b = 0;
while (charIndex < charCount) {
b = read();
if (b > 127) break;
chars[charIndex++] = (char)b;
}
// If a char was not ASCII, finish with slow path.
if (charIndex < charCount) readUtf8_slow(charCount, charIndex, b);
return new String(chars, 0, charCount);
}
private void readUtf8_slow (int charCount, int charIndex, int b) throws IOException {
char[] chars = this.chars;
while (true) {
switch (b >> 4) {
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
case 7:
chars[charIndex] = (char)b;
break;
case 12:
case 13:
chars[charIndex] = (char)((b & 0x1F) << 6 | read() & 0x3F);
break;
case 14:
chars[charIndex] = (char)((b & 0x0F) << 12 | (read() & 0x3F) << 6 | read() & 0x3F);
break;
}
if (++charIndex >= charCount) break;
b = read() & 0xFF;
}
}
}