/*
* Copyright 2006-2007 Jeremias Maerki.
*
* 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.google.zxing.datamatrix.encoder;
final class Base256Encoder implements Encoder {
@Override
public int getEncodingMode() {
return HighLevelEncoder.BASE256_ENCODATION;
}
@Override
public void encode(EncoderContext context) {
StringBuilder buffer = new StringBuilder();
buffer.append('\0'); // Initialize length field
while (context.hasMoreCharacters()) {
char c = context.getCurrentChar();
buffer.append(c);
context.pos++;
int newMode = HighLevelEncoder.lookAheadTest(context.getMessage(),
context.pos, getEncodingMode());
if (newMode != getEncodingMode()) {
context.signalEncoderChange(newMode);
break;
}
}
int dataCount = buffer.length() - 1;
int lengthFieldSize = 1;
int currentSize = context.getCodewordCount() + dataCount
+ lengthFieldSize;
context.updateSymbolInfo(currentSize);
boolean mustPad = (context.getSymbolInfo().getDataCapacity() - currentSize) > 0;
if (context.hasMoreCharacters() || mustPad) {
if (dataCount <= 249) {
buffer.setCharAt(0, (char) dataCount);
} else if (dataCount > 249 && dataCount <= 1555) {
buffer.setCharAt(0, (char) ((dataCount / 250) + 249));
buffer.insert(1, (char) (dataCount % 250));
} else {
throw new IllegalStateException(
"Message length not in valid ranges: " + dataCount);
}
}
for (int i = 0, c = buffer.length(); i < c; i++) {
context.writeCodeword(randomize255State(buffer.charAt(i),
context.getCodewordCount() + 1));
}
}
private static char randomize255State(char ch, int codewordPosition) {
int pseudoRandom = ((149 * codewordPosition) % 255) + 1;
int tempVariable = ch + pseudoRandom;
if (tempVariable <= 255) {
return (char) tempVariable;
} else {
return (char) (tempVariable - 256);
}
}
}