com.mchange.lang.ByteUtils Maven / Gradle / Ivy
/*
* Distributed as part of mchange-commons-java v.0.2.3
*
* Copyright (C) 2012 Machinery For Change, Inc.
*
* Author: Steve Waldman
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1, as
* published by the Free Software Foundation.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this software; see the file LICENSE. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*/
package com.mchange.lang;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.IOException;
public final class ByteUtils
{
public final static short UNSIGNED_MAX_VALUE = (Byte.MAX_VALUE * 2) + 1;
public static short toUnsigned(byte b)
{return (short) (b < 0 ? (UNSIGNED_MAX_VALUE + 1) + b : b);}
public static String toHexAscii(byte b)
{
StringWriter sw = new StringWriter(2);
addHexAscii(b, sw);
return sw.toString();
}
public static String toHexAscii(byte[] bytes)
{
int len = bytes.length;
StringWriter sw = new StringWriter(len * 2);
for (int i = 0; i < len; ++i)
addHexAscii(bytes[i], sw);
return sw.toString();
}
public static byte[] fromHexAscii(String s) throws NumberFormatException
{
try
{
int len = s.length();
if ((len % 2) != 0)
throw new NumberFormatException("Hex ascii must be exactly two digits per byte.");
int out_len = len / 2;
byte[] out = new byte[out_len];
int i = 0;
StringReader sr = new StringReader(s);
while (i < out_len)
{
int val = (16 * fromHexDigit(sr.read())) + fromHexDigit(sr.read());
out[i++] = (byte) val;
}
return out;
}
catch (IOException e)
{throw new InternalError("IOException reading from StringReader?!?!");}
}
static void addHexAscii(byte b, StringWriter sw)
{
short ub = toUnsigned(b);
int h1 = ub / 16;
int h2 = ub % 16;
sw.write(toHexDigit(h1));
sw.write(toHexDigit(h2));
}
private static int fromHexDigit(int c) throws NumberFormatException
{
if (c >= 0x30 && c < 0x3A)
return c - 0x30;
else if (c >= 0x41 && c < 0x47)
return c - 0x37;
else if (c >= 0x61 && c < 0x67)
return c - 0x57;
else
throw new NumberFormatException('\'' + c + "' is not a valid hexadecimal digit.");
}
/* note: we do no arg. checking, because */
/* we only ever call this from addHexAscii() */
/* above, and we are sure the args are okay */
private static char toHexDigit(int h)
{
char out;
if (h <= 9) out = (char) (h + 0x30);
else out = (char) (h + 0x37);
//System.err.println(h + ": " + out);
return out;
}
private ByteUtils()
{}
}