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Add instance number and element number support in symbol path. This c…
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…reate smaller path and allows more read to be packet in a single MultiRead requests. Numeric path elements are encoded as byte or short with proper segment type.
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@spelletier
spelletier committed Apr 10, 2018
1 parent 574a62d commit af8338a
Showing 1 changed file with 115 additions and 45 deletions.
160 changes: 115 additions & 45 deletions src/etherip/types/CNSymbolPath.java
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Original file line number Diff line number Diff line change
Expand Up @@ -9,17 +9,20 @@

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
* Control Net Path for element path
* <p>
* Example (with suitable static import):
* Control Net Path for element path. Support symbolic and numeric address elements in any part.
* <p>
* Examples (with suitable static import):
* </p><p>
* <code>CNPath path = Symbol.name("my_tag")</code>
*
* <code>CNPath path = Symbol.name("my_tag[1].Name")</code>
* <code>CNPath path = Symbol.name("123.1.Name")</code>
* </p>
* @author Kay Kasemir
*/
@SuppressWarnings("nls")
Expand All @@ -30,15 +33,24 @@ public class CNSymbolPath extends CNPath
* <p>
* Contains a string path and an optional array index
*/
class PathAndIndex
public static class PathElement
{
private final String path;
private static final int MAX_BYTE_VALUE = 255;
private final String path;
private final Integer index;
private boolean firstElement;

public PathAndIndex(final String path, final Integer index)
public PathElement(final boolean firstElement, final String path, final Integer index)
{
this.path = path;
this.index = index;
this.firstElement = firstElement;
if (path.matches("^[0-9]+$")) {
this.path = null;
this.index = Integer.parseInt(path);
}
else {
this.path = path;
this.index = index;
}
}

public String getPath()
Expand All @@ -50,6 +62,85 @@ public Integer getIndex()
{
return this.index;
}

public int getEncodedSize() {
int size = 0;
if (firstElement && path == null) {
size += 2; // Add space for Symbol Class ID
}

if (path != null) {
size += path.length() + 2;
if (needPad()) {
size += 1;
}
}
if (index != null) {
size += 2;
if (index > MAX_BYTE_VALUE) {
size += 2;
}
}
return size;
}

public void encode(final ByteBuffer buf) {
if (firstElement && path == null) {
encodeInstanceId(buf);
}
else {
encodeElementName(buf);
encodeElementId(buf);
}
}

private void encodeInstanceId(final ByteBuffer buf) {
buf.put(new byte[] {0x20, 0x6B}); // Logical Segment for Symbol Class ID
if (index > MAX_BYTE_VALUE) {
buf.put((byte) 0x25);
buf.put((byte) 0);
buf.putShort(index.shortValue());
}
else {
buf.put((byte) 0x24);
buf.put(index.byteValue());
}
}

private void encodeElementName(final ByteBuffer buf) {
if (path != null) {
// spec 4 p.21: "ANSI extended symbol segment"
buf.put((byte) 0x91);
buf.put((byte) path.length());
buf.put(path.getBytes());
if (this.needPad())
{
buf.put((byte) 0);
}
}
}

private void encodeElementId(final ByteBuffer buf) {
if (index != null)
{
if (index > MAX_BYTE_VALUE) {
buf.put((byte) 0x29);
buf.put((byte) 0);
buf.putShort(index.shortValue());
}
else {
buf.put((byte) 0x28);
buf.put(index.byteValue());
}
}
}

/** @return Is path of odd length, requiring a pad byte? */
private boolean needPad()
{
return (path.length() % 2) != 0;
}


@Override
public String toString()
Expand All @@ -64,16 +155,17 @@ public String toString()

private final Pattern PATTERN_BRACKETS = Pattern.compile("\\[(\\d+)\\]");

private final List<PathAndIndex> paths = new ArrayList<>();
private final List<PathElement> elements = new ArrayList<>();

/**
/**
* Initialize
*
* @param symbol
* Name of symbol
*/
protected CNSymbolPath(final String symbol)
{
boolean firstElement = true;
for (final String s : symbol.split("\\."))
{
final Matcher m = this.PATTERN_BRACKETS.matcher(s);
Expand All @@ -86,23 +178,23 @@ protected CNSymbolPath(final String symbol)
index = Integer.parseInt(match);
path = path.replace("[" + match + "]", "");
}
this.paths.add(new PathAndIndex(path, index));
this.elements.add(new PathElement(firstElement, path, index));
firstElement = false;
}
}

public List<PathElement> getElements() {
return Collections.unmodifiableList(elements);
}

/** {@inheritDoc} */
@Override
public int getRequestSize()
{ // End of string is padded if length is odd
int count = 0;
for (final PathAndIndex s : this.paths)
for (final PathElement s : this.elements)
{
count += 2 + s.getPath().length()
+ (this.needPad(s.getPath()) ? 1 : 0);
if (s.getIndex() != null)
{
count += 2;
}
count += s.getEncodedSize();
}
return count;
}
Expand All @@ -111,48 +203,26 @@ public int getRequestSize()
@Override
public void encode(final ByteBuffer buf, final StringBuilder log)
{
// spec 4 p.21: "ANSI extended symbol segment"
buf.put((byte) (this.getRequestSize() / 2));
for (final PathAndIndex pi : this.paths)
for (final PathElement pi : this.elements)
{
final String s = pi.getPath();
buf.put((byte) 0x91);
buf.put((byte) s.length());
buf.put(s.getBytes());
if (this.needPad(s))
{
buf.put((byte) 0);
}
final Integer index = pi.getIndex();
if (index != null)
{
// Path Segment 28, from wireshark
buf.put((byte) 0x28);
buf.put(index.byteValue());
}
pi.encode(buf);
}
}

/** @return Is path of odd length, requiring a pad byte? */
private boolean needPad(final String s)
{
// Findbugs: x%2==1 fails for negative numbers
return (s.length() % 2) != 0;
}

@Override
public String toString()
{
final StringBuilder buf = new StringBuilder();
buf.append("Path Symbol(0x91) ");
for (final PathAndIndex pi : this.paths)
for (final PathElement pi : this.elements)
{
if (buf.length() > 18)
{
buf.append(", ");
}
buf.append('\'').append(pi).append('\'');
if (this.needPad(pi.getPath()))
if (pi.needPad())
{
buf.append(", 0x00");
}
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