HexString.java

// ========================================================================
// Copyright 2008-2009 NEXCOM Systems
// ------------------------------------------------------------------------
// 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.rayo.core.sip;


public class HexString {

    private static final char __hexChars[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

    private static final char __hexCharsUC[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

    public static void appendHex(StringBuffer buf, int c) {
        buf.append(__hexCharsUC[(c & 0xf0) >> 4]);
        buf.append(__hexCharsUC[c & 0x0f]);
    }

    public static String toHexString(String s) {
        return toHexString(s.getBytes());
    }

    public static String toHexString(byte buffer[]) {
        return toHexString(buffer, 0, buffer.length);
    }

    public static String toHexString(byte b[], int offset, int length) {
        StringBuffer hex = new StringBuffer(2 * length);
        for (int i = offset; i < offset + length; i++) {
            hex.append(__hexChars[(b[i] & 0xf0) >> 4]);
            hex.append(__hexChars[b[i] & 0x0f]);
        }

        return hex.toString();
    }

    public static byte[] fromHexString(String hex) throws NumberFormatException {
        int length = hex.length();

        byte[] buf = new byte[(length + 1) / 2];
        boolean even = true;
        byte b = 0;
        int offset = 0;

        if ((length % 2) == 1) even = false;

        for (int i = 0; i < length; i++) {
            char c = hex.charAt(i);
            int nibble;

            if ((c >= '0') && (c <= '9'))
                nibble = c - '0';
            else if ((c >= 'A') && (c <= 'F'))
                nibble = c - 'A' + 0x0A;
            else if ((c >= 'a') && (c <= 'f'))
                nibble = c - 'a' + 0x0A;
            else
                throw new NumberFormatException("Invalid hex digit '" + c + "'.");

            if (even) {
                b = (byte) (nibble << 4);
            }
            else {
                b += (byte) nibble;
                buf[offset++] = b;
            }

            even = !even;
        }
        return buf;
    }

    public static String toDetailedHexString(byte[] b, int length) {
        StringBuffer sb = new StringBuffer(5 * length);

        int lines = (length >>> 4) + 1;

        for (int i = 0; i < lines; i++) {
            sb.append(__hexChars[(i >>> 4 & 0xf0) >> 4]);
            sb.append(__hexChars[i >>> 4 & 0x0f]);
            sb.append(__hexChars[(i << 4 & 0xf0) >> 4]);
            sb.append(__hexChars[i << 4 & 0x0f]);
            sb.append(' ');

            int n = (i == lines - 1) ? length & 0xf : 16;

            for (int j = 0; j < 16; j++) {
                if (j < n) {
                    int c = b[i * 16 + j];
                    sb.append(__hexChars[(c & 0xf0) >> 4]);
                    sb.append(__hexChars[c & 0x0f]);
                    sb.append(' ');
                }
                else
                    sb.append("   ");
            }

            for (int j = 0; j < n; j++) {
                int c = b[i * 16 + j] & 0xff;
                if (c > 0x1f && c < 0x7f)
                    sb.append((char) c);
                else
                    sb.append('.');
            }

            sb.append('\r');
            sb.append('\n');
        }
        return sb.toString();
    }

}