--- /dev/null
+/*
+ * Copyright (c) 2013 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+
+/**
+ *
+ */
+package org.opendaylight.controller.liblldp;
+
+import java.util.Arrays;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * BitBufferHelper class that provides utility methods to
+ * - fetch specific bits from a serialized stream of bits
+ * - convert bits to primitive data type - like short, int, long
+ * - store bits in specified location in stream of bits
+ * - convert primitive data types to stream of bits
+ */
+public abstract class BitBufferHelper {
+ protected static final Logger logger = LoggerFactory
+ .getLogger(BitBufferHelper.class);
+
+ public static final long ByteMask = 0xFF;
+
+ // Getters
+ // data: array where data are stored
+ // startOffset: bit from where to start reading
+ // numBits: number of bits to read
+ // All this function return an exception if overflow or underflow
+
+ /**
+ * Returns the first byte from the byte array
+ * @param byte[] data
+ * @return byte value
+ */
+ public static byte getByte(byte[] data) {
+ if ((data.length * NetUtils.NumBitsInAByte) > Byte.SIZE) {
+ try {
+ throw new BufferException(
+ "Container is too small for the number of requested bits");
+ } catch (BufferException e) {
+ logger.error("", e);
+ }
+ }
+ return (data[0]);
+ }
+
+ /**
+ * Returns the short value for the byte array passed.
+ * Size of byte array is restricted to Short.SIZE
+ * @param byte[] data
+ * @return short value
+ */
+ public static short getShort(byte[] data) {
+ if (data.length > Short.SIZE) {
+ try {
+ throw new BufferException(
+ "Container is too small for the number of requested bits");
+ } catch (BufferException e) {
+ logger.error("", e);
+ }
+ }
+ return (short) toNumber(data);
+ }
+
+ /**
+ * Returns the int value for the byte array passed.
+ * Size of byte array is restricted to Integer.SIZE
+ * @param byte[] data
+ * @return int - the integer value of byte array
+ */
+ public static int getInt(byte[] data) {
+ if (data.length > Integer.SIZE) {
+ try {
+ throw new BufferException(
+ "Container is too small for the number of requested bits");
+ } catch (BufferException e) {
+ logger.error("", e);
+ }
+ }
+ return (int) toNumber(data);
+ }
+
+ /**
+ * Returns the long value for the byte array passed.
+ * Size of byte array is restricted to Long.SIZE
+ * @param byte[] data
+ * @return long - the integer value of byte array
+ */
+ public static long getLong(byte[] data) {
+ if (data.length > Long.SIZE) {
+ try {
+ throw new BufferException(
+ "Container is too small for the number of requested bits");
+ } catch (Exception e) {
+ logger.error("", e);
+ }
+ }
+ return (long) toNumber(data);
+ }
+
+ /**
+ * Returns the short value for the last numBits of the byte array passed.
+ * Size of numBits is restricted to Short.SIZE
+ * @param byte[] data
+ * @param int - numBits
+ * @return short - the short value of byte array
+ */
+ public static short getShort(byte[] data, int numBits) {
+ if (numBits > Short.SIZE) {
+ try {
+ throw new BufferException(
+ "Container is too small for the number of requested bits");
+ } catch (BufferException e) {
+ logger.error("", e);
+ }
+ }
+ int startOffset = data.length * NetUtils.NumBitsInAByte - numBits;
+ byte[] bits = null;
+ try {
+ bits = BitBufferHelper.getBits(data, startOffset, numBits);
+ } catch (BufferException e) {
+ logger.error("", e);
+ }
+ return (short) toNumber(bits, numBits);
+ }
+
+ /**
+ * Returns the int value for the last numBits of the byte array passed.
+ * Size of numBits is restricted to Integer.SIZE
+ * @param byte[] data
+ * @param int - numBits
+ * @return int - the integer value of byte array
+ */
+ public static int getInt(byte[] data, int numBits) {
+ if (numBits > Integer.SIZE) {
+ try {
+ throw new BufferException(
+ "Container is too small for the number of requested bits");
+ } catch (BufferException e) {
+ logger.error("", e);
+ }
+ }
+ int startOffset = data.length * NetUtils.NumBitsInAByte - numBits;
+ byte[] bits = null;
+ try {
+ bits = BitBufferHelper.getBits(data, startOffset, numBits);
+ } catch (BufferException e) {
+ logger.error("", e);
+ }
+ return (int) toNumber(bits, numBits);
+ }
+
+ /**
+ * Returns the long value for the last numBits of the byte array passed.
+ * Size of numBits is restricted to Long.SIZE
+ * @param byte[] data
+ * @param int - numBits
+ * @return long - the integer value of byte array
+ */
+ public static long getLong(byte[] data, int numBits) {
+ if (numBits > Long.SIZE) {
+ try {
+ throw new BufferException(
+ "Container is too small for the number of requested bits");
+ } catch (BufferException e) {
+ logger.error("", e);
+ }
+ }
+ if (numBits > data.length * NetUtils.NumBitsInAByte) {
+ try {
+ throw new BufferException(
+ "Trying to read more bits than contained in the data buffer");
+ } catch (BufferException e) {
+ logger.error("", e);
+ }
+ }
+ int startOffset = data.length * NetUtils.NumBitsInAByte - numBits;
+ byte[] bits = null;
+ try {
+ bits = BitBufferHelper.getBits(data, startOffset, numBits);
+ } catch (BufferException e) {
+ logger.error("", e);
+ }
+ return (long) toNumber(bits, numBits);
+ }
+
+ /**
+ * Reads the specified number of bits from the passed byte array
+ * starting to read from the specified offset
+ * The bits read are stored in a byte array which size is dictated
+ * by the number of bits to be stored.
+ * The bits are stored in the byte array LSB aligned.
+ *
+ * Ex.
+ * Read 7 bits at offset 10
+ * 0 9 10 16 17
+ * 0101000010 | 0000101 | 1111001010010101011
+ * will be returned as {0,0,0,0,0,1,0,1}
+ *
+ * @param byte[] data
+ * @param int startOffset - offset to start fetching bits from data from
+ * @param int numBits - number of bits to be fetched from data
+ * @return byte [] - LSB aligned bits
+ *
+ * @throws BufferException
+ * when the startOffset and numBits parameters are not congruent
+ * with the data buffer size
+ */
+ public static byte[] getBits(byte[] data, int startOffset, int numBits)
+ throws BufferException {
+
+ int startByteOffset = 0;
+ int valfromcurr, valfromnext;
+ int extranumBits = numBits % NetUtils.NumBitsInAByte;
+ int extraOffsetBits = startOffset % NetUtils.NumBitsInAByte;
+ int numBytes = (numBits % NetUtils.NumBitsInAByte != 0) ? 1 + numBits
+ / NetUtils.NumBitsInAByte : numBits / NetUtils.NumBitsInAByte;
+ byte[] shiftedBytes = new byte[numBytes];
+ startByteOffset = startOffset / NetUtils.NumBitsInAByte;
+ byte[] bytes = new byte[numBytes];
+ if (numBits == 0) {
+ return bytes;
+ }
+
+ checkExceptions(data, startOffset, numBits);
+
+ if (extraOffsetBits == 0) {
+ if (extranumBits == 0) {
+ System.arraycopy(data, startByteOffset, bytes, 0, numBytes);
+ return bytes;
+ } else {
+ System.arraycopy(data, startByteOffset, bytes, 0, numBytes - 1);
+ bytes[numBytes - 1] = (byte) ((int) data[startByteOffset
+ + numBytes - 1] & getMSBMask(extranumBits));
+ }
+ } else {
+ int i;
+ for (i = 0; i < numBits / NetUtils.NumBitsInAByte; i++) {
+ // Reading numBytes starting from offset
+ valfromcurr = (data[startByteOffset + i])
+ & getLSBMask(NetUtils.NumBitsInAByte - extraOffsetBits);
+ valfromnext = (data[startByteOffset + i + 1])
+ & getMSBMask(extraOffsetBits);
+ bytes[i] = (byte) (valfromcurr << (extraOffsetBits) | (valfromnext >> (NetUtils.NumBitsInAByte - extraOffsetBits)));
+ }
+ // Now adding the rest of the bits if any
+ if (extranumBits != 0) {
+ if (extranumBits < (NetUtils.NumBitsInAByte - extraOffsetBits)) {
+ valfromnext = (byte) (data[startByteOffset + i] & ((getMSBMask(extranumBits)) >> extraOffsetBits));
+ bytes[i] = (byte) (valfromnext << extraOffsetBits);
+ } else if (extranumBits == (NetUtils.NumBitsInAByte - extraOffsetBits)) {
+ valfromcurr = (data[startByteOffset + i])
+ & getLSBMask(NetUtils.NumBitsInAByte
+ - extraOffsetBits);
+ bytes[i] = (byte) (valfromcurr << extraOffsetBits);
+ } else {
+ valfromcurr = (data[startByteOffset + i])
+ & getLSBMask(NetUtils.NumBitsInAByte
+ - extraOffsetBits);
+ valfromnext = (data[startByteOffset + i + 1])
+ & (getMSBMask(extranumBits
+ - (NetUtils.NumBitsInAByte - extraOffsetBits)));
+ bytes[i] = (byte) (valfromcurr << (extraOffsetBits) | (valfromnext >> (NetUtils.NumBitsInAByte - extraOffsetBits)));
+ }
+
+ }
+ }
+ // Aligns the bits to LSB
+ shiftedBytes = shiftBitsToLSB(bytes, numBits);
+ return shiftedBytes;
+ }
+
+ // Setters
+ // data: array where data will be stored
+ // input: the data that need to be stored in the data array
+ // startOffset: bit from where to start writing
+ // numBits: number of bits to read
+
+ /**
+ * Bits are expected to be stored in the input byte array from LSB
+ * @param byte[] - data to set the input byte
+ * @param byte - input byte to be inserted
+ * @param startOffset - offset of data[] to start inserting byte from
+ * @param numBits - number of bits of input to be inserted into data[]
+ *
+ * @throws BufferException
+ * when the input, startOffset and numBits are not congruent
+ * with the data buffer size
+ */
+ public static void setByte(byte[] data, byte input, int startOffset,
+ int numBits) throws BufferException {
+ byte[] inputByteArray = new byte[1];
+ Arrays.fill(inputByteArray, 0, 1, input);
+ setBytes(data, inputByteArray, startOffset, numBits);
+ }
+
+ /**
+ * Bits are expected to be stored in the input byte array from LSB
+ * @param byte[] - data to set the input byte
+ * @param byte[] - input bytes to be inserted
+ * @param startOffset - offset of data[] to start inserting byte from
+ * @param numBits - number of bits of input to be inserted into data[]
+ * @return void
+ * @throws BufferException
+ * when the startOffset and numBits parameters are not congruent
+ * with data and input buffers' size
+ */
+ public static void setBytes(byte[] data, byte[] input, int startOffset,
+ int numBits) throws BufferException {
+ checkExceptions(data, startOffset, numBits);
+ insertBits(data, input, startOffset, numBits);
+ }
+
+ /**
+ * Returns numBits 1's in the MSB position
+ *
+ * @param numBits
+ * @return
+ */
+ public static int getMSBMask(int numBits) {
+ int mask = 0;
+ for (int i = 0; i < numBits; i++) {
+ mask = mask | (1 << (7 - i));
+ }
+ return mask;
+ }
+
+ /**
+ * Returns numBits 1's in the LSB position
+ *
+ * @param numBits
+ * @return
+ */
+ public static int getLSBMask(int numBits) {
+ int mask = 0;
+ for (int i = 0; i < numBits; i++) {
+ mask = mask | (1 << i);
+ }
+ return mask;
+ }
+
+ /**
+ * Returns the numerical value of the byte array passed
+ *
+ * @param byte[] - array
+ * @return long - numerical value of byte array passed
+ */
+ static public long toNumber(byte[] array) {
+ long ret = 0;
+ long length = array.length;
+ int value = 0;
+ for (int i = 0; i < length; i++) {
+ value = array[i];
+ if (value < 0)
+ value += 256;
+ ret = ret
+ | (long) ((long) value << ((length - i - 1) * NetUtils.NumBitsInAByte));
+ }
+ return ret;
+ }
+
+ /**
+ * Returns the numerical value of the last numBits (LSB bits) of the byte
+ * array passed
+ *
+ * @param byte[] - array
+ * @param int - numBits
+ * @return long - numerical value of byte array passed
+ */
+ static public long toNumber(byte[] array, int numBits) {
+ int length = numBits / NetUtils.NumBitsInAByte;
+ int bitsRest = numBits % NetUtils.NumBitsInAByte;
+ int startOffset = array.length - length;
+ long ret = 0;
+ int value = 0;
+
+ value = array[startOffset - 1] & getLSBMask(bitsRest);
+ value = (array[startOffset - 1] < 0) ? (array[startOffset - 1] + 256)
+ : array[startOffset - 1];
+ ret = ret
+ | (value << ((array.length - startOffset) * NetUtils.NumBitsInAByte));
+
+ for (int i = startOffset; i < array.length; i++) {
+ value = array[i];
+ if (value < 0)
+ value += 256;
+ ret = ret
+ | (long) ((long) value << ((array.length - i - 1) * NetUtils.NumBitsInAByte));
+ }
+
+ return ret;
+ }
+
+ /**
+ * Accepts a number as input and returns its value in byte form in LSB
+ * aligned form example: input = 5000 [1001110001000] bytes = 19, -120
+ * [00010011] [10001000]
+ *
+ * @param Number
+ * @return byte[]
+ *
+ */
+
+ public static byte[] toByteArray(Number input) {
+ Class<? extends Number> dataType = input.getClass();
+ short size = 0;
+ long longValue = input.longValue();
+
+ if (dataType == Byte.class || dataType == byte.class) {
+ size = Byte.SIZE;
+ } else if (dataType == Short.class || dataType == short.class) {
+ size = Short.SIZE;
+ } else if (dataType == Integer.class || dataType == int.class) {
+ size = Integer.SIZE;
+ } else if (dataType == Long.class || dataType == long.class) {
+ size = Long.SIZE;
+ } else {
+ throw new IllegalArgumentException(
+ "Parameter must one of the following: Short/Int/Long\n");
+ }
+
+ int length = size / NetUtils.NumBitsInAByte;
+ byte bytes[] = new byte[length];
+
+ // Getting the bytes from input value
+ for (int i = 0; i < length; i++) {
+ bytes[i] = (byte) ((longValue >> (NetUtils.NumBitsInAByte * (length
+ - i - 1))) & ByteMask);
+ }
+ return bytes;
+ }
+
+ /**
+ * Accepts a number as input and returns its value in byte form in MSB
+ * aligned form example: input = 5000 [1001110001000] bytes = -114, 64
+ * [10011100] [01000000]
+ *
+ * @param Number
+ * input
+ * @param int numBits - the number of bits to be returned
+ * @return byte[]
+ *
+ */
+ public static byte[] toByteArray(Number input, int numBits) {
+ Class<? extends Number> dataType = input.getClass();
+ short size = 0;
+ long longValue = input.longValue();
+
+ if (dataType == Short.class) {
+ size = Short.SIZE;
+ } else if (dataType == Integer.class) {
+ size = Integer.SIZE;
+ } else if (dataType == Long.class) {
+ size = Long.SIZE;
+ } else {
+ throw new IllegalArgumentException(
+ "Parameter must one of the following: Short/Int/Long\n");
+ }
+
+ int length = size / NetUtils.NumBitsInAByte;
+ byte bytes[] = new byte[length];
+ byte[] inputbytes = new byte[length];
+ byte shiftedBytes[];
+
+ // Getting the bytes from input value
+ for (int i = 0; i < length; i++) {
+ bytes[i] = (byte) ((longValue >> (NetUtils.NumBitsInAByte * (length
+ - i - 1))) & ByteMask);
+ }
+
+ if ((bytes[0] == 0 && dataType == Long.class)
+ || (bytes[0] == 0 && dataType == Integer.class)) {
+ int index = 0;
+ for (index = 0; index < length; ++index) {
+ if (bytes[index] != 0) {
+ bytes[0] = bytes[index];
+ break;
+ }
+ }
+ System.arraycopy(bytes, index, inputbytes, 0, length - index);
+ Arrays.fill(bytes, length - index + 1, length - 1, (byte) 0);
+ } else {
+ System.arraycopy(bytes, 0, inputbytes, 0, length);
+ }
+
+ shiftedBytes = shiftBitsToMSB(inputbytes, numBits);
+
+ return shiftedBytes;
+ }
+
+ /**
+ * Takes an LSB aligned byte array and returned the LSB numBits in a MSB
+ * aligned byte array
+ *
+ * @param inputbytes
+ * @param numBits
+ * @return
+ */
+ /**
+ * It aligns the last numBits bits to the head of the byte array following
+ * them with numBits % 8 zero bits.
+ *
+ * Example: For inputbytes = [00000111][01110001] and numBits = 12 it
+ * returns: shiftedBytes = [01110111][00010000]
+ *
+ * @param byte[] inputBytes
+ * @param int numBits - number of bits to be left aligned
+ * @return byte[]
+ */
+ public static byte[] shiftBitsToMSB(byte[] inputBytes, int numBits) {
+ int numBitstoShiftBy = 0, leadZeroesMSB = 8, numEndRestBits = 0;
+ int size = inputBytes.length;
+ byte[] shiftedBytes = new byte[size];
+ int i;
+
+ for (i = 0; i < Byte.SIZE; i++) {
+ if (((byte) (inputBytes[0] & getMSBMask(i + 1))) != 0) {
+ leadZeroesMSB = i;
+ break;
+ }
+ }
+
+ if (numBits % NetUtils.NumBitsInAByte == 0) {
+ numBitstoShiftBy = 0;
+ } else {
+ numBitstoShiftBy = ((NetUtils.NumBitsInAByte - (numBits % NetUtils.NumBitsInAByte)) < leadZeroesMSB) ? (NetUtils.NumBitsInAByte - (numBits % NetUtils.NumBitsInAByte))
+ : leadZeroesMSB;
+ }
+ if (numBitstoShiftBy == 0) {
+ return inputBytes;
+ }
+
+ if (numBits < NetUtils.NumBitsInAByte) {
+ // inputbytes.length = 1 OR read less than a byte
+ shiftedBytes[0] = (byte) ((inputBytes[0] & getLSBMask(numBits)) << numBitstoShiftBy);
+ } else {
+ // # of bits to read from last byte
+ numEndRestBits = NetUtils.NumBitsInAByte
+ - (inputBytes.length * NetUtils.NumBitsInAByte - numBits - numBitstoShiftBy);
+
+ for (i = 0; i < (size - 1); i++) {
+ if ((i + 1) == (size - 1)) {
+ if (numEndRestBits > numBitstoShiftBy) {
+ shiftedBytes[i] = (byte) ((inputBytes[i] << numBitstoShiftBy) | ((inputBytes[i + 1] & getMSBMask(numBitstoShiftBy)) >> (numEndRestBits - numBitstoShiftBy)));
+ shiftedBytes[i + 1] = (byte) ((inputBytes[i + 1] & getLSBMask(numEndRestBits
+ - numBitstoShiftBy)) << numBitstoShiftBy);
+ } else
+ shiftedBytes[i] = (byte) ((inputBytes[i] << numBitstoShiftBy) | ((inputBytes[i + 1] & getMSBMask(numEndRestBits)) >> (NetUtils.NumBitsInAByte - numEndRestBits)));
+ }
+ shiftedBytes[i] = (byte) ((inputBytes[i] << numBitstoShiftBy) | (inputBytes[i + 1] & getMSBMask(numBitstoShiftBy)) >> (NetUtils.NumBitsInAByte - numBitstoShiftBy));
+ }
+
+ }
+ return shiftedBytes;
+ }
+
+ /**
+ * It aligns the first numBits bits to the right end of the byte array
+ * preceding them with numBits % 8 zero bits.
+ *
+ * Example: For inputbytes = [01110111][00010000] and numBits = 12 it
+ * returns: shiftedBytes = [00000111][01110001]
+ *
+ * @param byte[] inputBytes
+ * @param int numBits - number of bits to be right aligned
+ * @return byte[]
+ */
+ public static byte[] shiftBitsToLSB(byte[] inputBytes, int numBits) {
+ int numBytes = inputBytes.length;
+ int numBitstoShift = numBits % NetUtils.NumBitsInAByte;
+ byte[] shiftedBytes = new byte[numBytes];
+ int inputLsb = 0, inputMsb = 0;
+
+ if (numBitstoShift == 0) {
+ return inputBytes;
+ }
+
+ for (int i = 1; i < numBytes; i++) {
+ inputLsb = inputBytes[i - 1]
+ & getLSBMask(NetUtils.NumBitsInAByte - numBitstoShift);
+ inputLsb = (inputLsb < 0) ? (inputLsb + 256) : inputLsb;
+ inputMsb = inputBytes[i] & getMSBMask(numBitstoShift);
+ inputMsb = (inputBytes[i] < 0) ? (inputBytes[i] + 256)
+ : inputBytes[i];
+ shiftedBytes[i] = (byte) ((inputLsb << numBitstoShift) | (inputMsb >> (NetUtils.NumBitsInAByte - numBitstoShift)));
+ }
+ inputMsb = inputBytes[0] & (getMSBMask(numBitstoShift));
+ inputMsb = (inputMsb < 0) ? (inputMsb + 256) : inputMsb;
+ shiftedBytes[0] = (byte) (inputMsb >> (NetUtils.NumBitsInAByte - numBitstoShift));
+ return shiftedBytes;
+ }
+
+ /**
+ * Insert in the data buffer at position dictated by the offset the number
+ * of bits specified from the input data byte array. The input byte array
+ * has the bits stored starting from the LSB
+ *
+ * @param byte[] data
+ * @param byte[] inputdata
+ * @param int startOffset
+ * @param int numBits
+ */
+ public static void insertBits(byte[] data, byte[] inputdataLSB,
+ int startOffset, int numBits) {
+ byte[] inputdata = shiftBitsToMSB(inputdataLSB, numBits); // Align to
+ // MSB the
+ // passed byte
+ // array
+ int numBytes = numBits / NetUtils.NumBitsInAByte;
+ int startByteOffset = startOffset / NetUtils.NumBitsInAByte;
+ int extraOffsetBits = startOffset % NetUtils.NumBitsInAByte;
+ int extranumBits = numBits % NetUtils.NumBitsInAByte;
+ int RestBits = numBits % NetUtils.NumBitsInAByte;
+ int InputMSBbits = 0, InputLSBbits = 0;
+ int i;
+
+ if (numBits == 0) {
+ return;
+ }
+
+ if (extraOffsetBits == 0) {
+ if (extranumBits == 0) {
+ numBytes = numBits / NetUtils.NumBitsInAByte;
+ System.arraycopy(inputdata, 0, data, startByteOffset, numBytes);
+ } else {
+ System.arraycopy(inputdata, 0, data, startByteOffset, numBytes);
+ data[startByteOffset + numBytes] = (byte) (data[startByteOffset
+ + numBytes] | (inputdata[numBytes] & getMSBMask(extranumBits)));
+ }
+ } else {
+ for (i = 0; i < numBytes; i++) {
+ if (i != 0)
+ InputLSBbits = (inputdata[i - 1] & getLSBMask(extraOffsetBits));
+ InputMSBbits = (byte) (inputdata[i] & (getMSBMask(NetUtils.NumBitsInAByte
+ - extraOffsetBits)));
+ InputMSBbits = (InputMSBbits >= 0) ? InputMSBbits
+ : InputMSBbits + 256;
+ data[startByteOffset + i] = (byte) (data[startByteOffset + i]
+ | (InputLSBbits << (NetUtils.NumBitsInAByte - extraOffsetBits)) | (InputMSBbits >> extraOffsetBits));
+ InputMSBbits = InputLSBbits = 0;
+ }
+ if (RestBits < (NetUtils.NumBitsInAByte - extraOffsetBits)) {
+ if (numBytes != 0)
+ InputLSBbits = (inputdata[i - 1] & getLSBMask(extraOffsetBits));
+ InputMSBbits = (byte) (inputdata[i] & (getMSBMask(RestBits)));
+ InputMSBbits = (InputMSBbits >= 0) ? InputMSBbits
+ : InputMSBbits + 256;
+ data[startByteOffset + i] = (byte) ((data[startByteOffset + i])
+ | (InputLSBbits << (NetUtils.NumBitsInAByte - extraOffsetBits)) | (InputMSBbits >> extraOffsetBits));
+ } else if (RestBits == (NetUtils.NumBitsInAByte - extraOffsetBits)) {
+ if (numBytes != 0)
+ InputLSBbits = (inputdata[i - 1] & getLSBMask(extraOffsetBits));
+ InputMSBbits = (byte) (inputdata[i] & (getMSBMask(NetUtils.NumBitsInAByte
+ - extraOffsetBits)));
+ InputMSBbits = (InputMSBbits >= 0) ? InputMSBbits
+ : InputMSBbits + 256;
+ data[startByteOffset + i] = (byte) (data[startByteOffset + i]
+ | (InputLSBbits << (NetUtils.NumBitsInAByte - extraOffsetBits)) | (InputMSBbits >> extraOffsetBits));
+ } else {
+ if (numBytes != 0)
+ InputLSBbits = (inputdata[i - 1] & getLSBMask(extraOffsetBits));
+ InputMSBbits = (byte) (inputdata[i] & (getMSBMask(NetUtils.NumBitsInAByte
+ - extraOffsetBits)));
+ InputMSBbits = (InputMSBbits >= 0) ? InputMSBbits
+ : InputMSBbits + 256;
+ data[startByteOffset + i] = (byte) (data[startByteOffset + i]
+ | (InputLSBbits << (NetUtils.NumBitsInAByte - extraOffsetBits)) | (InputMSBbits >> extraOffsetBits));
+
+ InputLSBbits = (inputdata[i] & (getLSBMask(RestBits
+ - (NetUtils.NumBitsInAByte - extraOffsetBits)) << (NetUtils.NumBitsInAByte - RestBits)));
+ data[startByteOffset + i + 1] = (byte) (data[startByteOffset
+ + i + 1] | (InputLSBbits << (NetUtils.NumBitsInAByte - extraOffsetBits)));
+ }
+ }
+ }
+
+ /**
+ * Checks for overflow and underflow exceptions
+ * @param data
+ * @param startOffset
+ * @param numBits
+ * @throws PacketException when the startOffset and numBits parameters
+ * are not congruent with the data buffer's size
+ */
+ public static void checkExceptions(byte[] data, int startOffset, int numBits)
+ throws BufferException {
+ int endOffsetByte;
+ int startByteOffset;
+ endOffsetByte = startOffset
+ / NetUtils.NumBitsInAByte
+ + numBits
+ / NetUtils.NumBitsInAByte
+ + ((numBits % NetUtils.NumBitsInAByte != 0) ? 1 : ((startOffset
+ % NetUtils.NumBitsInAByte != 0) ? 1 : 0));
+ startByteOffset = startOffset / NetUtils.NumBitsInAByte;
+
+ if (data == null) {
+ throw new BufferException("data[] is null\n");
+ }
+
+ if ((startOffset < 0) || (startByteOffset >= data.length)
+ || (endOffsetByte > data.length) || (numBits < 0)
+ || (numBits > NetUtils.NumBitsInAByte * data.length)) {
+ throw new BufferException(
+ "Illegal arguement/out of bound exception - data.length = "
+ + data.length + " startOffset = " + startOffset
+ + " numBits " + numBits);
+ }
+ }
+}
Code Review / controller.git / blobdiff