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/**
* @author ETSI / STF462 / Alexandre Berge
* @version $URL$
* $Id$
*/
package org.etsi.ttcn.codec;
import java.util.Map;
import java.util.TreeMap;
import org.etsi.common.ByteHelper;
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public class CodecBuffer {
/**
* Raw byte storage array. Last byte may be a "partial byte", i.e. some of its bits may not be significants
* @see bits
*/
protected byte[] buffer;
/**
* Number of significant bits in the "partial byte"
* Significant bits are always stored "left-aligned" (i.e. MSBs) in the "partial byte"
* @see buffer
*/
protected int bits;
/**
* Marker storage
*/
protected Map<String, Marker> markers = new TreeMap<String, Marker>();
/**
* Some useful byte masks
*/
private byte[] masks = new byte[]{(byte)0x00, (byte)0x80, (byte)0xC0, (byte)0xE0, (byte)0xF0, (byte)0xF8, (byte)0xFC, (byte)0xFE};
/**
* Some useful byte masks
*/
private byte[] nomasks = new byte[]{(byte)0xFF, (byte)0x7F, (byte)0x3F, (byte)0x1F, (byte)0x0F, (byte)0x07, (byte)0x03, (byte)0x01};
/**
* Main constructor. Initialises an empty buffer
*/
public CodecBuffer() {
bits = 0;
buffer = new byte[]{};
}
/**
* Constructor. Initialises the buffer using provided byte array
* @param bytes Initial content of the buffer
*/
public CodecBuffer(byte[] bytes) {
bits = 0;
buffer = bytes.clone();
}
/**
* Overwrite content of current buffer using data of newBuffer
* @param newBuffer CodecBuffer containing new data
*/
public void overwriteWith(CodecBuffer newBuffer) {
bits = newBuffer.bits;
buffer = newBuffer.buffer.clone();
markers = new TreeMap<String, Marker>(newBuffer.markers);
}
/**
* Retrieves the number of significant bits in the buffer.
* Warning: getNbBytes() != (getNbBits() * 8)
* @return The number of significant bits in the buffer
* @see getNbBytes()
*/
public int getNbBits() {
if(bits > 0) {
return (buffer.length - 1) * 8 + bits;
}
return buffer.length * 8;
}
/**
* Retrieves the number of bytes used to store the buffer.
* Warning: getNbBytes() != (getNbBits() * 8)
* @return The number of bytes used to store the buffer
* @see getNbBits()
*/
public int getNbBytes() {
return buffer.length;
}
/**
* Concatenates current CodecBuffer and the CodecBuffer passed as parameter.
* Markers of buffer2 are preserved and integrated into the current CodecBuffer.
* @param buffer2 The CodecBuffer to be appended
*/
public void append(CodecBuffer buffer2) {
// copy buffer content
int nbBits = getNbBits();
if(buffer2.getNbBits() > 0) {
appendBits(buffer2.getBits(), buffer2.getNbBits());
}
// integrate markers
for(Map.Entry<String, Marker> entry : buffer2.markers.entrySet()) {
String key = entry.getKey();
Marker marker = entry.getValue();
marker.move(nbBits);
markers.put(key, marker);
}
}
/**
* Associates a new marker to current CodecBuffer.
* Inserting marker with name identical to a previously inserted one will overwrite it.
* @param key Name of the marker
* @param pos Position of the marker relative to the current position
* @param callback Optional callback object to be executed later, or null
* @see runCallbacks()
*/
public void setMarker(String key, int pos, IMarkerCallback callback) {
markers.put(key, new Marker(pos, callback));
}
/**
* Executes all the callbacks associated to current CodecBuffer's markers
* @see setMarkers()
*/
public void runCallbacks() {
// TERFactory.getInstance().logDebug("Running callbacks...");
for(Map.Entry<String, Marker> entry : markers.entrySet()) {
String key = entry.getKey();
// TERFactory.getInstance().logDebug("Running callback: " + key);
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Marker marker = entry.getValue();
IMarkerCallback callback = marker.getCallback();
if(callback != null) {
CodecBuffer Left = getBuffer(0, marker.getPos());
CodecBuffer Right = getBuffer(marker.getPos(), getNbBits() - marker.getPos());
callback.run(key, Left, Right);
// Overwrite self with Left+Right
// TODO: take care if Right or Left have change to much.
Left.append(Right);
buffer = Left.buffer;
bits = Left.bits;
}
}
}
/**
* Creates a new CodecBuffer from current CodecBuffer's content
* Markers of current CodecBuffer are preserved and integrated into the new CodecBuffer.
* @param start Start point. Bit offset from current position
* @param length Amount of bits to be copied
* @return The new CodecBuffer
*/
public CodecBuffer getBuffer(int start, int length) {
// TODO: check param validity
CodecBuffer res = new CodecBuffer();
res.setBits(getBits(start, length), length);
for(Map.Entry<String, Marker> entry : markers.entrySet()) {
String key = entry.getKey();
Marker marker = entry.getValue();
int pos = marker.getPos();
if(pos >= start && pos < (start + length)) {
res.setMarker(key, pos - start, marker.getCallback());
}
}
return res;
}
/**
* Appends some raw bytes at the end of the current CodecBuffer
* @param origBytes Bytes to be appended
*/
public void appendBytes(byte[] origBytes) {
byte[] bytes = origBytes.clone();
int lastByte = buffer.length - 1;
buffer = ByteHelper.concat(buffer, bytes);
if(bits != 0) {
for(int i=0; i < bytes.length; i++) {
buffer[lastByte] &= masks[bits];
buffer[lastByte] |= ((bytes[i] >>> bits) & nomasks[bits]);
lastByte++;
buffer[lastByte] = (byte)(buffer[lastByte] << (8 - bits));
}
buffer[buffer.length - 1] &= masks[bits];
}
}
/**
* Appends some raw bits at the end of the current CodecBuffer
* @param origBytes Byte array used to store the bits to be appended.
* It MUST be right-aligned. First byte (origBytes[0]) may be a
* partial byte if 'nbBits' is not a multiple of 8.
* In this case MSBs of this byte are ignored and not copied
* @param nbBits Number of significant bits in 'origBytes'
*/
public void appendBits(byte[] origBytes, int nbBits) {
byte[] bytes = origBytes.clone();
int rbits = nbBits % 8;
int nbBytes = nbBits / 8 + ((rbits > 0)?1:0);
int lastByte = buffer.length - 1;
// Left-align received bytes
if(rbits !=0) {
int i;
for(i=(bytes.length - nbBytes); i < (nbBytes - 1); i++) {
bytes[i] = (byte)(bytes[i] << (8 - rbits));
bytes[i] |= ((bytes[i+1] >>> rbits) & nomasks[rbits]);
}
bytes[i] = (byte)(bytes[i] << (8 - rbits));
bytes[i] &= masks[rbits];
}
buffer = ByteHelper.concat(buffer, ByteHelper.extract(bytes, (bytes.length - nbBytes), nbBytes));
if(bits != 0) {
int i;
for(i=lastByte; i < (lastByte + nbBytes); i++) {
buffer[i] &= masks[bits];
buffer[i] |= ((buffer[i+1] >>> bits) & nomasks[bits]);
buffer[i+1] = (byte)(buffer[i+1] << (8 - bits));
}
buffer[i] &= masks[bits];
if((rbits > 0) && (rbits + bits <= 8)) {
// Remove trailing byte (garbage)
buffer = ByteHelper.extract(buffer, 0, buffer.length - 1);
}
}
bits += nbBits;
bits %= 8;
}
/**
* Overwrite the content of CodecBuffer using the provided bytes
* @param bytes New content of the CodecBuffer
* @see setBits()
*/
public void setBytes(byte[] bytes) {
buffer = bytes.clone();
bits = 0;
markers.clear();
}
/**
* Overwrite the content of CodecBuffer using the provided bits
* @param bytes Byte array used to store the bits to be used.
* It MUST be right-aligned. First byte (origBytes[0]) may be a
* partial byte if 'nbBits' is not a multiple of 8.
* In this case MSBs of this byte are ignored and not copied
* @param nbBits Number of significant bits in 'bytes'
* @see setBytes()
*/
public void setBits(byte[] bytes, int nbBits) {
if(nbBits == 0) {
bits = 0;
buffer = new byte[]{};
}
else {
int i;
int rbits = nbBits % 8;
int nbBytes = nbBits / 8 + ((rbits > 0)?1:0);
bits = rbits;
buffer = bytes.clone();
if(bits !=0) {
for(i=(bytes.length - nbBytes); i < (nbBytes - 1); i++) {
buffer[i] = (byte)(buffer[i] << (8 - bits));
buffer[i] |= ((buffer[i+1] >>> bits) & nomasks[bits]);
}
buffer[i] = (byte)(buffer[i] << (8 - bits));
buffer[i] &= masks[bits];
}
}
markers.clear();
}
/**
* Extracts some bytes at the beginning of the buffer. Read bytes are discarded from the buffer.
* @param nbBytes Number of bytes to be read
* @return Byte array containing the 'nbBytes' first bytes of the buffer.
* Byte array's length may be shorter than requested if buffer does not
* contain enough bytes
* @see getBytes()
*/
public byte[] readBytes(int nbBytes) {
byte[] result = getBytes(0, nbBytes);
int newLength = getNbBits() - (nbBytes * 8);
if(result != null) {
if(newLength > 0) {
setBits(getBits(nbBytes * 8, newLength), newLength);
}
else {
bits = 0;
buffer = new byte[] {};
}
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}
return result;
// TODO: move markers
}
/**
* Extracts some bits at the beginning of the buffer. Read bits are discarded from the buffer.
* @param nbBytes Number of bits to be read
* @return Byte array containing the 'nbBits' first bits of the buffer.
* Number of returned bits may be smaller than requested if buffer does not
* contain enough bits. Returned byte array is right-aligned.
* First byte may be a partial byte if 'nbBits' is not a multiple of 8.
* In this case MSBs of this byte are not significants and padded with '0's
* @see getBits()
*/
public byte[] readBits(int nbBits) {
byte[] result = getBits(0, nbBits);
int newLength = getNbBits() - nbBits;
byte[] newBuffer = getBits(nbBits, newLength);
if(result != null) {
setBits(newBuffer, newLength);
}
return result;
// TODO: move markers
}
/**
* Retrieves the raw content of the CodecBuffer
* @return Raw byte array used to store CodecBuffer's content
* Returned byte array is left-aligned.
* Last byte may be a partial byte if 'bits' is not null.
* In this case LSBs of this byte are not significants and their value is undetermined
*/
public byte[] getBytes() {
return buffer;
}
/**
* Retrieves some bytes from the CodecBuffer. Returned bytes are not removed from the buffer
* @param start Start point (octet index)
* @param nbBytes Number of bytes to be returned
* @return Extracted bytes.
* Returned byte array is left-aligned.
* Last byte may be a "partial byte" if it is the last byte of CodecBuffer and if 'bits' is not null.
* In this case LSBs of this byte are not significants and their value is undetermined
* @see ReadBytes()
*/
public byte[] getBytes(int start, int nbBytes) {
if(start > buffer.length) {
TERFactory.getInstance().logDebug("bad start: " + start);
return null;
}
if((start + nbBytes) > buffer.length) {
TERFactory.getInstance().logDebug("bad length: " + (start + nbBytes) + " (" + buffer.length + " bytes remaining)");
TERFactory.getInstance().logDebug("bad length: " + (nbBytes) + " (" + buffer.length + " bytes remaining)");
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return null;
}
return ByteHelper.extract(buffer, start, nbBytes);
}
/**
* Retrieves all the bits from the CodecBuffer. Returned bits are not removed from the buffer
* @return Extracted bits stored in a byte array.
* Returned byte array is right-aligned.
* First byte may be a "partial byte" if 'nbBits' is not a multiple of 8.
* In this case MSBs of this byte are not significants and their value is '0'
* @see ReadBits()
*/
public byte[] getBits() {
return getBits(0, getNbBits());
}
/**
* Retrieves some bits from the CodecBuffer. Returned bits are not removed from the buffer
* @param start Start point (bit index)
* @param nbBits Number of bits to be returned
* @return Extracted bits stored in a byte array.
* Returned byte array is right-aligned.
* First byte may be a "partial byte" if 'nbBits' is not a multiple of 8.
* In this case MSBs of this byte are not significants and their value is '0'
* @see ReadBits()
*/
public byte[] getBits(int start, int nbBits) {
int byteIndex = start / 8;
int bitOffset = start % 8;
int nbBytes = ((bitOffset > 0)?1:0) + (((nbBits - 8 + bitOffset) / 8) + ((bitOffset==0)?1:0)) + ((((nbBits - 8 + bitOffset) % 8) > 0)?1:0);
// leading partial byte complete bytes trailing partial byte
if(byteIndex > buffer.length) {
TERFactory.getInstance().logDebug("bad start: " + byteIndex + "(" + start + ")" + " (" + buffer.length + " bytes remaining)");
return null;
}
if((byteIndex + nbBytes) > buffer.length) {
TERFactory.getInstance().logDebug("bad length: " + (byteIndex + nbBytes) + "(" + nbBits + ")" + " (" + buffer.length + " bytes remaining)");
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return null;
}
byte[] tmp = ByteHelper.extract(buffer, byteIndex, nbBytes);
if(bitOffset != 0) {
tmp[0] = (byte)(tmp[0] << bitOffset);
for(int i=1; i < tmp.length; i++) {
tmp[i-1] &= masks[8 - bitOffset];
tmp[i-1] |= ((tmp[i] >>> (8 - bitOffset)) & nomasks[8 - bitOffset]);
tmp[i] = (byte)(tmp[i] << bitOffset);
}
}
tmp = ByteHelper.extract(tmp, 0, nbBits / 8 + (((nbBits % 8) > 0)?1:0));
if(nbBits % 8 > 0) {
for(int i=tmp.length-1; i >= 0; i--) {
tmp[i] = (byte)((tmp[i] >>> (8 - (nbBits % 8))) & nomasks[8 - (nbBits % 8)]);
if(i > 0) {
tmp[i] |= (byte)(tmp[i-1] << (nbBits % 8));
}
}
}
return tmp;
}
/**
* Retrieves some bits from the CodecBuffer. Returned bits are not removed from the buffer
* @param markerKey Name of the marker serving as starting point for the extraction
* @param nbBits Number of bits to be returned
* @return Extracted bits stored in a byte array.
* Returned byte array is right-aligned.
* First byte may be a "partial byte" if 'nbBits' is not a multiple of 8.
* In this case MSBs of this byte are not significants and their value is '0'
* @see ReadBits()
*/
public byte[] getBits(String markerKey, int nbBits) {
Marker marker = markers.get(markerKey);
if(marker != null) {
return getBits(marker.getPos(), nbBits);
}
return null;
}
/**
* Private class used to represent markers that can be insterted in CodecBuffer
*/
private class Marker {
/**
* Constructor.
* @param pos Position of the marker relative to the current position
* @param callback Optional callback object to be executed later, or null
*/
public Marker(int pos, IMarkerCallback callback) {
this.pos = pos;
this.callback = callback;
}
/**
* Retrieve the position of the marker (bit offset from buffer's start).
* @return The position of the marker
*/
public int getPos() {
return pos;
}
/**
* Retrieve the callback object associated to the marker.
* @return The callback object associated to the marker, or null
*/
public IMarkerCallback getCallback() {
return callback;
}
/**
* Changes the position of the marker in the buffer
* @param nbBits Position offset from marker's current position (can be negative)
*/
public void move(int nbBits) {
pos += nbBits;
}
/**
* Current position of the marker
*/
private int pos;
/**
* Callback object associated to the marker
*/
private IMarkerCallback callback;
}
}