src/core/datamatrix/decoder/DataBlock.ts
import Version from './Version';
import IllegalArgumentException from '../../IllegalArgumentException';
/*
* Copyright 2008 ZXing authors
*
* 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.
*/
/**
* <p>Encapsulates a block of data within a Data Matrix Code. Data Matrix Codes may split their data into
* multiple blocks, each of which is a unit of data and error-correction codewords. Each
* is represented by an instance of this class.</p>
*
* @author bbrown@google.com (Brian Brown)
*/
export default class DataBlock {
private numDataCodewords: number;
private codewords: Uint8Array;
constructor(numDataCodewords: number, codewords: Uint8Array) {
this.numDataCodewords = numDataCodewords;
this.codewords = codewords;
}
/**
* <p>When Data Matrix Codes use multiple data blocks, they actually interleave the bytes of each of them.
* That is, the first byte of data block 1 to n is written, then the second bytes, and so on. This
* method will separate the data into original blocks.</p>
*
* @param rawCodewords bytes as read directly from the Data Matrix Code
* @param version version of the Data Matrix Code
* @return DataBlocks containing original bytes, "de-interleaved" from representation in the
* Data Matrix Code
*/
static getDataBlocks(rawCodewords: Int8Array,
version: Version): DataBlock[] {
// Figure out the number and size of data blocks used by this version
const ecBlocks = version.getECBlocks();
// First count the total number of data blocks
let totalBlocks = 0;
const ecBlockArray = ecBlocks.getECBlocks();
for (let ecBlock of ecBlockArray) {
totalBlocks += ecBlock.getCount();
}
// Now establish DataBlocks of the appropriate size and number of data codewords
const result: DataBlock[] = new Array(totalBlocks);
let numResultBlocks = 0;
for (let ecBlock of ecBlockArray) {
for (let i = 0; i < ecBlock.getCount(); i++) {
const numDataCodewords = ecBlock.getDataCodewords();
const numBlockCodewords = ecBlocks.getECCodewords() + numDataCodewords;
result[numResultBlocks++] = new DataBlock(numDataCodewords, new Uint8Array(numBlockCodewords));
}
}
// All blocks have the same amount of data, except that the last n
// (where n may be 0) have 1 less byte. Figure out where these start.
// TODO(bbrown): There is only one case where there is a difference for Data Matrix for size 144
const longerBlocksTotalCodewords = result[0].codewords.length;
// int shorterBlocksTotalCodewords = longerBlocksTotalCodewords - 1;
const longerBlocksNumDataCodewords = longerBlocksTotalCodewords - ecBlocks.getECCodewords();
const shorterBlocksNumDataCodewords = longerBlocksNumDataCodewords - 1;
// The last elements of result may be 1 element shorter for 144 matrix
// first fill out as many elements as all of them have minus 1
let rawCodewordsOffset = 0;
for (let i = 0; i < shorterBlocksNumDataCodewords; i++) {
for (let j = 0; j < numResultBlocks; j++) {
result[j].codewords[i] = rawCodewords[rawCodewordsOffset++];
}
}
// Fill out the last data block in the longer ones
const specialVersion = version.getVersionNumber() === 24;
const numLongerBlocks = specialVersion ? 8 : numResultBlocks;
for (let j = 0; j < numLongerBlocks; j++) {
result[j].codewords[longerBlocksNumDataCodewords - 1] = rawCodewords[rawCodewordsOffset++];
}
// Now add in error correction blocks
const max = result[0].codewords.length;
for (let i = longerBlocksNumDataCodewords; i < max; i++) {
for (let j = 0; j < numResultBlocks; j++) {
const jOffset = specialVersion ? (j + 8) % numResultBlocks : j;
const iOffset = specialVersion && jOffset > 7 ? i - 1 : i;
result[jOffset].codewords[iOffset] = rawCodewords[rawCodewordsOffset++];
}
}
if (rawCodewordsOffset !== rawCodewords.length) {
throw new IllegalArgumentException();
}
return result;
}
getNumDataCodewords(): number {
return this.numDataCodewords;
}
getCodewords(): Uint8Array {
return this.codewords;
}
}