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808
zxing.core/xx/pdf417/decoder/DecodedBitStreamParser.cs
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808
zxing.core/xx/pdf417/decoder/DecodedBitStreamParser.cs
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@@ -0,0 +1,808 @@
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/*
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* Copyright 2009 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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using System;
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using System.Text;
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using System.Numerics;
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using ZXing.Common;
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namespace ZXing.PDF417.Internal
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{
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/// <summary>
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/// <p>This class contains the methods for decoding the PDF417 codewords.</p>
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///
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/// <author>SITA Lab (kevin.osullivan@sita.aero)</author>
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/// </summary>
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internal static class DecodedBitStreamParser
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{
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private enum Mode
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{
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ALPHA,
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LOWER,
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MIXED,
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PUNCT,
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ALPHA_SHIFT,
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PUNCT_SHIFT
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}
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private const int TEXT_COMPACTION_MODE_LATCH = 900;
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private const int BYTE_COMPACTION_MODE_LATCH = 901;
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private const int NUMERIC_COMPACTION_MODE_LATCH = 902;
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private const int BYTE_COMPACTION_MODE_LATCH_6 = 924;
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private const int ECI_USER_DEFINED = 925;
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private const int ECI_GENERAL_PURPOSE = 926;
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private const int ECI_CHARSET = 927;
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private const int BEGIN_MACRO_PDF417_CONTROL_BLOCK = 928;
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private const int BEGIN_MACRO_PDF417_OPTIONAL_FIELD = 923;
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private const int MACRO_PDF417_TERMINATOR = 922;
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private const int MODE_SHIFT_TO_BYTE_COMPACTION_MODE = 913;
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private const int MAX_NUMERIC_CODEWORDS = 15;
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private const int PL = 25;
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private const int LL = 27;
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private const int AS = 27;
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private const int ML = 28;
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private const int AL = 28;
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private const int PS = 29;
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private const int PAL = 29;
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private static readonly char[] PUNCT_CHARS = {
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';', '<', '>', '@', '[', '\\', ']', '_', '`', '~', '!',
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'\r', '\t', ',', ':', '\n', '-', '.', '$', '/', '"', '|', '*',
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'(', ')', '?', '{', '}', '\''
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};
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private static readonly char[] MIXED_CHARS = {
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '&',
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'\r', '\t', ',', ':', '#', '-', '.', '$', '/', '+', '%', '*',
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'=', '^'
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};
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/// <summary>
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/// Table containing values for the exponent of 900.
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/// This is used in the numeric compaction decode algorithm.
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/// </summary>
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private static readonly BigInteger[] EXP900;
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static DecodedBitStreamParser()
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{
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EXP900 = new BigInteger[16];
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EXP900[0] = BigInteger.One;
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BigInteger nineHundred = new BigInteger(900);
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EXP900[1] = nineHundred;
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for (int i = 2; i < EXP900.Length; i++)
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{
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EXP900[i] = BigInteger.Multiply(EXP900[i - 1], nineHundred);
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}
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}
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private const int NUMBER_OF_SEQUENCE_CODEWORDS = 2;
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internal static DecoderResult decode(int[] codewords, String ecLevel)
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{
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var result = new StringBuilder(codewords.Length * 2);
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// Get compaction mode
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int codeIndex = 1;
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int code = codewords[codeIndex++];
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var resultMetadata = new PDF417ResultMetadata();
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Encoding encoding = null;
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while (codeIndex < codewords[0])
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{
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switch (code)
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{
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case TEXT_COMPACTION_MODE_LATCH:
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codeIndex = textCompaction(codewords, codeIndex, result);
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break;
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case BYTE_COMPACTION_MODE_LATCH:
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case BYTE_COMPACTION_MODE_LATCH_6:
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codeIndex = byteCompaction(code, codewords, encoding ?? (encoding = getEncoding(PDF417HighLevelEncoder.DEFAULT_ENCODING_NAME)), codeIndex, result);
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break;
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case MODE_SHIFT_TO_BYTE_COMPACTION_MODE:
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result.Append((char)codewords[codeIndex++]);
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break;
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case NUMERIC_COMPACTION_MODE_LATCH:
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codeIndex = numericCompaction(codewords, codeIndex, result);
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break;
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case ECI_CHARSET:
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var charsetECI = CharacterSetECI.getCharacterSetECIByValue(codewords[codeIndex++]);
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encoding = getEncoding(charsetECI.EncodingName);
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break;
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case ECI_GENERAL_PURPOSE:
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// Can't do anything with generic ECI; skip its 2 characters
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codeIndex += 2;
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break;
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case ECI_USER_DEFINED:
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// Can't do anything with user ECI; skip its 1 character
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codeIndex++;
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break;
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case BEGIN_MACRO_PDF417_CONTROL_BLOCK:
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codeIndex = decodeMacroBlock(codewords, codeIndex, resultMetadata);
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break;
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case BEGIN_MACRO_PDF417_OPTIONAL_FIELD:
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case MACRO_PDF417_TERMINATOR:
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// Should not see these outside a macro block
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return null;
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default:
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// Default to text compaction. During testing numerous barcodes
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// appeared to be missing the starting mode. In these cases defaulting
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// to text compaction seems to work.
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codeIndex--;
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codeIndex = textCompaction(codewords, codeIndex, result);
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break;
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}
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if (codeIndex < 0)
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return null;
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if (codeIndex < codewords.Length)
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{
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code = codewords[codeIndex++];
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}
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else
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{
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return null;
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}
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}
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if (result.Length == 0)
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{
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return null;
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}
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var decoderResult = new DecoderResult(null, result.ToString(), null, ecLevel);
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decoderResult.Other = resultMetadata;
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return decoderResult;
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}
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private static Encoding getEncoding(string encodingName)
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{
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Encoding encoding = null;
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try
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{
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encoding = Encoding.GetEncoding(encodingName);
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}
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#if (WINDOWS_PHONE70 || WINDOWS_PHONE71 || SILVERLIGHT4 || SILVERLIGHT5 || NETFX_CORE || MONOANDROID || MONOTOUCH)
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catch (ArgumentException)
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{
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try
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{
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// Silverlight only supports a limited number of character sets, trying fallback to UTF-8
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encoding = Encoding.GetEncoding("UTF-8");
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}
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catch (Exception)
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{
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}
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}
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#endif
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#if WindowsCE
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catch (PlatformNotSupportedException)
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{
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try
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{
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// WindowsCE doesn't support all encodings. But it is device depended.
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// So we try here the some different ones
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if (encodingName == "ISO-8859-1")
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{
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encoding = Encoding.GetEncoding(1252);
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}
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else
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{
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encoding = Encoding.GetEncoding("UTF-8");
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}
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}
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catch (Exception)
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{
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}
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}
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#endif
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catch (Exception)
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{
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return null;
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}
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return encoding;
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}
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private static int decodeMacroBlock(int[] codewords, int codeIndex, PDF417ResultMetadata resultMetadata)
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{
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if (codeIndex + NUMBER_OF_SEQUENCE_CODEWORDS > codewords[0])
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{
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// we must have at least two bytes left for the segment index
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return -1;
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}
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int[] segmentIndexArray = new int[NUMBER_OF_SEQUENCE_CODEWORDS];
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for (int i = 0; i < NUMBER_OF_SEQUENCE_CODEWORDS; i++, codeIndex++)
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{
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segmentIndexArray[i] = codewords[codeIndex];
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}
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String s = decodeBase900toBase10(segmentIndexArray, NUMBER_OF_SEQUENCE_CODEWORDS);
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if (s == null)
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return -1;
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resultMetadata.SegmentIndex = Int32.Parse(s);
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StringBuilder fileId = new StringBuilder();
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codeIndex = textCompaction(codewords, codeIndex, fileId);
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resultMetadata.FileId = fileId.ToString();
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if (codewords[codeIndex] == BEGIN_MACRO_PDF417_OPTIONAL_FIELD)
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{
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codeIndex++;
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int[] additionalOptionCodeWords = new int[codewords[0] - codeIndex];
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int additionalOptionCodeWordsIndex = 0;
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bool end = false;
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while ((codeIndex < codewords[0]) && !end)
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{
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int code = codewords[codeIndex++];
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if (code < TEXT_COMPACTION_MODE_LATCH)
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{
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additionalOptionCodeWords[additionalOptionCodeWordsIndex++] = code;
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}
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else
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{
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switch (code)
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{
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case MACRO_PDF417_TERMINATOR:
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resultMetadata.IsLastSegment = true;
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codeIndex++;
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end = true;
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break;
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default:
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return -1;
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}
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}
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}
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resultMetadata.OptionalData = new int[additionalOptionCodeWordsIndex];
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Array.Copy(additionalOptionCodeWords, resultMetadata.OptionalData, additionalOptionCodeWordsIndex);
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}
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else if (codewords[codeIndex] == MACRO_PDF417_TERMINATOR)
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{
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resultMetadata.IsLastSegment = true;
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codeIndex++;
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}
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return codeIndex;
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}
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/// <summary>
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/// Text Compaction mode (see 5.4.1.5) permits all printable ASCII characters to be
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/// encoded, i.e. values 32 - 126 inclusive in accordance with ISO/IEC 646 (IRV), as
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/// well as selected control characters.
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///
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/// <param name="codewords">The array of codewords (data + error)</param>
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/// <param name="codeIndex">The current index into the codeword array.</param>
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/// <param name="result">The decoded data is appended to the result.</param>
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/// <returns>The next index into the codeword array.</returns>
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/// </summary>
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private static int textCompaction(int[] codewords, int codeIndex, StringBuilder result)
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{
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// 2 character per codeword
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int[] textCompactionData = new int[(codewords[0] - codeIndex) << 1];
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// Used to hold the byte compaction value if there is a mode shift
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int[] byteCompactionData = new int[(codewords[0] - codeIndex) << 1];
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int index = 0;
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bool end = false;
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while ((codeIndex < codewords[0]) && !end)
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{
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int code = codewords[codeIndex++];
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if (code < TEXT_COMPACTION_MODE_LATCH)
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{
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textCompactionData[index] = code / 30;
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textCompactionData[index + 1] = code % 30;
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index += 2;
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}
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else
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{
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switch (code)
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||||
{
|
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case TEXT_COMPACTION_MODE_LATCH:
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// reinitialize text compaction mode to alpha sub mode
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textCompactionData[index++] = TEXT_COMPACTION_MODE_LATCH;
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break;
|
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case BYTE_COMPACTION_MODE_LATCH:
|
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case BYTE_COMPACTION_MODE_LATCH_6:
|
||||
case NUMERIC_COMPACTION_MODE_LATCH:
|
||||
case BEGIN_MACRO_PDF417_CONTROL_BLOCK:
|
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case BEGIN_MACRO_PDF417_OPTIONAL_FIELD:
|
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case MACRO_PDF417_TERMINATOR:
|
||||
codeIndex--;
|
||||
end = true;
|
||||
break;
|
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case MODE_SHIFT_TO_BYTE_COMPACTION_MODE:
|
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// The Mode Shift codeword 913 shall cause a temporary
|
||||
// switch from Text Compaction mode to Byte Compaction mode.
|
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// This switch shall be in effect for only the next codeword,
|
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// after which the mode shall revert to the prevailing sub-mode
|
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// of the Text Compaction mode. Codeword 913 is only available
|
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// in Text Compaction mode; its use is described in 5.4.2.4.
|
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textCompactionData[index] = MODE_SHIFT_TO_BYTE_COMPACTION_MODE;
|
||||
code = codewords[codeIndex++];
|
||||
byteCompactionData[index] = code;
|
||||
index++;
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
decodeTextCompaction(textCompactionData, byteCompactionData, index, result);
|
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return codeIndex;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// The Text Compaction mode includes all the printable ASCII characters
|
||||
/// (i.e. values from 32 to 126) and three ASCII control characters: HT or tab
|
||||
/// (ASCII value 9), LF or line feed (ASCII value 10), and CR or carriage
|
||||
/// return (ASCII value 13). The Text Compaction mode also includes various latch
|
||||
/// and shift characters which are used exclusively within the mode. The Text
|
||||
/// Compaction mode encodes up to 2 characters per codeword. The compaction rules
|
||||
/// for converting data into PDF417 codewords are defined in 5.4.2.2. The sub-mode
|
||||
/// switches are defined in 5.4.2.3.
|
||||
///
|
||||
/// <param name="textCompactionData">The text compaction data.</param>
|
||||
/// <param name="byteCompactionData">The byte compaction data if there</param>
|
||||
/// was a mode shift.
|
||||
/// <param name="length">The size of the text compaction and byte compaction data.</param>
|
||||
/// <param name="result">The decoded data is appended to the result.</param>
|
||||
/// </summary>
|
||||
private static void decodeTextCompaction(int[] textCompactionData,
|
||||
int[] byteCompactionData,
|
||||
int length,
|
||||
StringBuilder result)
|
||||
{
|
||||
// Beginning from an initial state of the Alpha sub-mode
|
||||
// The default compaction mode for PDF417 in effect at the start of each symbol shall always be Text
|
||||
// Compaction mode Alpha sub-mode (uppercase alphabetic). A latch codeword from another mode to the Text
|
||||
// Compaction mode shall always switch to the Text Compaction Alpha sub-mode.
|
||||
Mode subMode = Mode.ALPHA;
|
||||
Mode priorToShiftMode = Mode.ALPHA;
|
||||
int i = 0;
|
||||
while (i < length)
|
||||
{
|
||||
int subModeCh = textCompactionData[i];
|
||||
char? ch = null;
|
||||
switch (subMode)
|
||||
{
|
||||
case Mode.ALPHA:
|
||||
// Alpha (uppercase alphabetic)
|
||||
if (subModeCh < 26)
|
||||
{
|
||||
// Upper case Alpha Character
|
||||
ch = (char)('A' + subModeCh);
|
||||
}
|
||||
else
|
||||
{
|
||||
if (subModeCh == 26)
|
||||
{
|
||||
ch = ' ';
|
||||
}
|
||||
else if (subModeCh == LL)
|
||||
{
|
||||
subMode = Mode.LOWER;
|
||||
}
|
||||
else if (subModeCh == ML)
|
||||
{
|
||||
subMode = Mode.MIXED;
|
||||
}
|
||||
else if (subModeCh == PS)
|
||||
{
|
||||
// Shift to punctuation
|
||||
priorToShiftMode = subMode;
|
||||
subMode = Mode.PUNCT_SHIFT;
|
||||
}
|
||||
else if (subModeCh == MODE_SHIFT_TO_BYTE_COMPACTION_MODE)
|
||||
{
|
||||
// TODO Does this need to use the current character encoding? See other occurrences below
|
||||
result.Append((char)byteCompactionData[i]);
|
||||
}
|
||||
else if (subModeCh == TEXT_COMPACTION_MODE_LATCH)
|
||||
{
|
||||
subMode = Mode.ALPHA;
|
||||
}
|
||||
}
|
||||
break;
|
||||
|
||||
case Mode.LOWER:
|
||||
// Lower (lowercase alphabetic)
|
||||
if (subModeCh < 26)
|
||||
{
|
||||
ch = (char)('a' + subModeCh);
|
||||
}
|
||||
else
|
||||
{
|
||||
if (subModeCh == 26)
|
||||
{
|
||||
ch = ' ';
|
||||
}
|
||||
else if (subModeCh == AS)
|
||||
{
|
||||
// Shift to alpha
|
||||
priorToShiftMode = subMode;
|
||||
subMode = Mode.ALPHA_SHIFT;
|
||||
}
|
||||
else if (subModeCh == ML)
|
||||
{
|
||||
subMode = Mode.MIXED;
|
||||
}
|
||||
else if (subModeCh == PS)
|
||||
{
|
||||
// Shift to punctuation
|
||||
priorToShiftMode = subMode;
|
||||
subMode = Mode.PUNCT_SHIFT;
|
||||
}
|
||||
else if (subModeCh == MODE_SHIFT_TO_BYTE_COMPACTION_MODE)
|
||||
{
|
||||
result.Append((char)byteCompactionData[i]);
|
||||
}
|
||||
else if (subModeCh == TEXT_COMPACTION_MODE_LATCH)
|
||||
{
|
||||
subMode = Mode.ALPHA;
|
||||
}
|
||||
}
|
||||
break;
|
||||
|
||||
case Mode.MIXED:
|
||||
// Mixed (numeric and some punctuation)
|
||||
if (subModeCh < PL)
|
||||
{
|
||||
ch = MIXED_CHARS[subModeCh];
|
||||
}
|
||||
else
|
||||
{
|
||||
if (subModeCh == PL)
|
||||
{
|
||||
subMode = Mode.PUNCT;
|
||||
}
|
||||
else if (subModeCh == 26)
|
||||
{
|
||||
ch = ' ';
|
||||
}
|
||||
else if (subModeCh == LL)
|
||||
{
|
||||
subMode = Mode.LOWER;
|
||||
}
|
||||
else if (subModeCh == AL)
|
||||
{
|
||||
subMode = Mode.ALPHA;
|
||||
}
|
||||
else if (subModeCh == PS)
|
||||
{
|
||||
// Shift to punctuation
|
||||
priorToShiftMode = subMode;
|
||||
subMode = Mode.PUNCT_SHIFT;
|
||||
}
|
||||
else if (subModeCh == MODE_SHIFT_TO_BYTE_COMPACTION_MODE)
|
||||
{
|
||||
result.Append((char)byteCompactionData[i]);
|
||||
}
|
||||
else if (subModeCh == TEXT_COMPACTION_MODE_LATCH)
|
||||
{
|
||||
subMode = Mode.ALPHA;
|
||||
}
|
||||
}
|
||||
break;
|
||||
|
||||
case Mode.PUNCT:
|
||||
// Punctuation
|
||||
if (subModeCh < PAL)
|
||||
{
|
||||
ch = PUNCT_CHARS[subModeCh];
|
||||
}
|
||||
else
|
||||
{
|
||||
if (subModeCh == PAL)
|
||||
{
|
||||
subMode = Mode.ALPHA;
|
||||
}
|
||||
else if (subModeCh == MODE_SHIFT_TO_BYTE_COMPACTION_MODE)
|
||||
{
|
||||
result.Append((char)byteCompactionData[i]);
|
||||
}
|
||||
else if (subModeCh == TEXT_COMPACTION_MODE_LATCH)
|
||||
{
|
||||
subMode = Mode.ALPHA;
|
||||
}
|
||||
}
|
||||
break;
|
||||
|
||||
case Mode.ALPHA_SHIFT:
|
||||
// Restore sub-mode
|
||||
subMode = priorToShiftMode;
|
||||
if (subModeCh < 26)
|
||||
{
|
||||
ch = (char)('A' + subModeCh);
|
||||
}
|
||||
else
|
||||
{
|
||||
if (subModeCh == 26)
|
||||
{
|
||||
ch = ' ';
|
||||
}
|
||||
else if (subModeCh == TEXT_COMPACTION_MODE_LATCH)
|
||||
{
|
||||
subMode = Mode.ALPHA;
|
||||
}
|
||||
}
|
||||
break;
|
||||
|
||||
case Mode.PUNCT_SHIFT:
|
||||
// Restore sub-mode
|
||||
subMode = priorToShiftMode;
|
||||
if (subModeCh < PAL)
|
||||
{
|
||||
ch = PUNCT_CHARS[subModeCh];
|
||||
}
|
||||
else
|
||||
{
|
||||
if (subModeCh == PAL)
|
||||
{
|
||||
subMode = Mode.ALPHA;
|
||||
}
|
||||
else if (subModeCh == MODE_SHIFT_TO_BYTE_COMPACTION_MODE)
|
||||
{
|
||||
// PS before Shift-to-Byte is used as a padding character,
|
||||
// see 5.4.2.4 of the specification
|
||||
result.Append((char)byteCompactionData[i]);
|
||||
}
|
||||
else if (subModeCh == TEXT_COMPACTION_MODE_LATCH)
|
||||
{
|
||||
subMode = Mode.ALPHA;
|
||||
}
|
||||
}
|
||||
break;
|
||||
}
|
||||
if (ch != null)
|
||||
{
|
||||
// Append decoded character to result
|
||||
result.Append(ch.Value);
|
||||
}
|
||||
i++;
|
||||
}
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Byte Compaction mode (see 5.4.3) permits all 256 possible 8-bit byte values to be encoded.
|
||||
/// This includes all ASCII characters value 0 to 127 inclusive and provides for international
|
||||
/// character set support.
|
||||
///
|
||||
/// <param name="mode">The byte compaction mode i.e. 901 or 924</param>
|
||||
/// <param name="codewords">The array of codewords (data + error)</param>
|
||||
/// <param name="encoding">Currently active character encoding</param>
|
||||
/// <param name="codeIndex">The current index into the codeword array.</param>
|
||||
/// <param name="result">The decoded data is appended to the result.</param>
|
||||
/// <returns>The next index into the codeword array.</returns>
|
||||
/// </summary>
|
||||
private static int byteCompaction(int mode, int[] codewords, Encoding encoding, int codeIndex, StringBuilder result)
|
||||
{
|
||||
var decodedBytes = new System.IO.MemoryStream();
|
||||
if (mode == BYTE_COMPACTION_MODE_LATCH)
|
||||
{
|
||||
// Total number of Byte Compaction characters to be encoded
|
||||
// is not a multiple of 6
|
||||
int count = 0;
|
||||
long value = 0;
|
||||
int[] byteCompactedCodewords = new int[6];
|
||||
bool end = false;
|
||||
int nextCode = codewords[codeIndex++];
|
||||
while ((codeIndex < codewords[0]) && !end)
|
||||
{
|
||||
byteCompactedCodewords[count++] = nextCode;
|
||||
// Base 900
|
||||
value = 900 * value + nextCode;
|
||||
nextCode = codewords[codeIndex++];
|
||||
// perhaps it should be ok to check only nextCode >= TEXT_COMPACTION_MODE_LATCH
|
||||
if (nextCode == TEXT_COMPACTION_MODE_LATCH ||
|
||||
nextCode == BYTE_COMPACTION_MODE_LATCH ||
|
||||
nextCode == NUMERIC_COMPACTION_MODE_LATCH ||
|
||||
nextCode == BYTE_COMPACTION_MODE_LATCH_6 ||
|
||||
nextCode == BEGIN_MACRO_PDF417_CONTROL_BLOCK ||
|
||||
nextCode == BEGIN_MACRO_PDF417_OPTIONAL_FIELD ||
|
||||
nextCode == MACRO_PDF417_TERMINATOR)
|
||||
{
|
||||
codeIndex--;
|
||||
end = true;
|
||||
}
|
||||
else
|
||||
{
|
||||
if ((count%5 == 0) && (count > 0))
|
||||
{
|
||||
// Decode every 5 codewords
|
||||
// Convert to Base 256
|
||||
for (int j = 0; j < 6; ++j)
|
||||
{
|
||||
decodedBytes.WriteByte((byte)(value >> (8 * (5 - j))));
|
||||
}
|
||||
value = 0;
|
||||
count = 0;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// if the end of all codewords is reached the last codeword needs to be added
|
||||
if (codeIndex == codewords[0] && nextCode < TEXT_COMPACTION_MODE_LATCH)
|
||||
byteCompactedCodewords[count++] = nextCode;
|
||||
|
||||
// If Byte Compaction mode is invoked with codeword 901,
|
||||
// the last group of codewords is interpreted directly
|
||||
// as one byte per codeword, without compaction.
|
||||
for (int i = 0; i < count; i++)
|
||||
{
|
||||
decodedBytes.WriteByte((byte)byteCompactedCodewords[i]);
|
||||
}
|
||||
}
|
||||
else if (mode == BYTE_COMPACTION_MODE_LATCH_6)
|
||||
{
|
||||
// Total number of Byte Compaction characters to be encoded
|
||||
// is an integer multiple of 6
|
||||
int count = 0;
|
||||
long value = 0;
|
||||
bool end = false;
|
||||
while (codeIndex < codewords[0] && !end)
|
||||
{
|
||||
int code = codewords[codeIndex++];
|
||||
if (code < TEXT_COMPACTION_MODE_LATCH)
|
||||
{
|
||||
count++;
|
||||
// Base 900
|
||||
value = 900 * value + code;
|
||||
}
|
||||
else
|
||||
{
|
||||
if (code == TEXT_COMPACTION_MODE_LATCH ||
|
||||
code == BYTE_COMPACTION_MODE_LATCH ||
|
||||
code == NUMERIC_COMPACTION_MODE_LATCH ||
|
||||
code == BYTE_COMPACTION_MODE_LATCH_6 ||
|
||||
code == BEGIN_MACRO_PDF417_CONTROL_BLOCK ||
|
||||
code == BEGIN_MACRO_PDF417_OPTIONAL_FIELD ||
|
||||
code == MACRO_PDF417_TERMINATOR)
|
||||
{
|
||||
codeIndex--;
|
||||
end = true;
|
||||
}
|
||||
}
|
||||
if ((count % 5 == 0) && (count > 0))
|
||||
{
|
||||
// Decode every 5 codewords
|
||||
// Convert to Base 256
|
||||
for (int j = 0; j < 6; ++j)
|
||||
{
|
||||
decodedBytes.WriteByte((byte)(value >> (8 * (5 - j))));
|
||||
}
|
||||
value = 0;
|
||||
count = 0;
|
||||
}
|
||||
}
|
||||
}
|
||||
var bytes = decodedBytes.ToArray();
|
||||
result.Append(encoding.GetString(bytes, 0, bytes.Length));
|
||||
return codeIndex;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Numeric Compaction mode (see 5.4.4) permits efficient encoding of numeric data strings.
|
||||
///
|
||||
/// <param name="codewords">The array of codewords (data + error)</param>
|
||||
/// <param name="codeIndex">The current index into the codeword array.</param>
|
||||
/// <param name="result">The decoded data is appended to the result.</param>
|
||||
/// <returns>The next index into the codeword array.</returns>
|
||||
/// </summary>
|
||||
private static int numericCompaction(int[] codewords, int codeIndex, StringBuilder result)
|
||||
{
|
||||
int count = 0;
|
||||
bool end = false;
|
||||
|
||||
int[] numericCodewords = new int[MAX_NUMERIC_CODEWORDS];
|
||||
|
||||
while (codeIndex < codewords[0] && !end)
|
||||
{
|
||||
int code = codewords[codeIndex++];
|
||||
if (codeIndex == codewords[0])
|
||||
{
|
||||
end = true;
|
||||
}
|
||||
if (code < TEXT_COMPACTION_MODE_LATCH)
|
||||
{
|
||||
numericCodewords[count] = code;
|
||||
count++;
|
||||
}
|
||||
else
|
||||
{
|
||||
if (code == TEXT_COMPACTION_MODE_LATCH ||
|
||||
code == BYTE_COMPACTION_MODE_LATCH ||
|
||||
code == BYTE_COMPACTION_MODE_LATCH_6 ||
|
||||
code == BEGIN_MACRO_PDF417_CONTROL_BLOCK ||
|
||||
code == BEGIN_MACRO_PDF417_OPTIONAL_FIELD ||
|
||||
code == MACRO_PDF417_TERMINATOR)
|
||||
{
|
||||
codeIndex--;
|
||||
end = true;
|
||||
}
|
||||
}
|
||||
if (count % MAX_NUMERIC_CODEWORDS == 0 ||
|
||||
code == NUMERIC_COMPACTION_MODE_LATCH ||
|
||||
end)
|
||||
{
|
||||
// Re-invoking Numeric Compaction mode (by using codeword 902
|
||||
// while in Numeric Compaction mode) serves to terminate the
|
||||
// current Numeric Compaction mode grouping as described in 5.4.4.2,
|
||||
// and then to start a new one grouping.
|
||||
if (count > 0)
|
||||
{
|
||||
String s = decodeBase900toBase10(numericCodewords, count);
|
||||
if (s == null)
|
||||
return -1;
|
||||
result.Append(s);
|
||||
count = 0;
|
||||
}
|
||||
}
|
||||
}
|
||||
return codeIndex;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Convert a list of Numeric Compacted codewords from Base 900 to Base 10.
|
||||
/// EXAMPLE
|
||||
/// Encode the fifteen digit numeric string 000213298174000
|
||||
/// Prefix the numeric string with a 1 and set the initial value of
|
||||
/// t = 1 000 213 298 174 000
|
||||
/// Calculate codeword 0
|
||||
/// d0 = 1 000 213 298 174 000 mod 900 = 200
|
||||
///
|
||||
/// t = 1 000 213 298 174 000 div 900 = 1 111 348 109 082
|
||||
/// Calculate codeword 1
|
||||
/// d1 = 1 111 348 109 082 mod 900 = 282
|
||||
///
|
||||
/// t = 1 111 348 109 082 div 900 = 1 234 831 232
|
||||
/// Calculate codeword 2
|
||||
/// d2 = 1 234 831 232 mod 900 = 632
|
||||
///
|
||||
/// t = 1 234 831 232 div 900 = 1 372 034
|
||||
/// Calculate codeword 3
|
||||
/// d3 = 1 372 034 mod 900 = 434
|
||||
///
|
||||
/// t = 1 372 034 div 900 = 1 524
|
||||
/// Calculate codeword 4
|
||||
/// d4 = 1 524 mod 900 = 624
|
||||
///
|
||||
/// t = 1 524 div 900 = 1
|
||||
/// Calculate codeword 5
|
||||
/// d5 = 1 mod 900 = 1
|
||||
/// t = 1 div 900 = 0
|
||||
/// Codeword sequence is: 1, 624, 434, 632, 282, 200
|
||||
///
|
||||
/// Decode the above codewords involves
|
||||
/// 1 x 900 power of 5 + 624 x 900 power of 4 + 434 x 900 power of 3 +
|
||||
/// 632 x 900 power of 2 + 282 x 900 power of 1 + 200 x 900 power of 0 = 1000213298174000
|
||||
///
|
||||
/// Remove leading 1 => Result is 000213298174000
|
||||
/// <param name="codewords">The array of codewords</param>
|
||||
/// <param name="count">The number of codewords</param>
|
||||
/// <returns>The decoded string representing the Numeric data.</returns>
|
||||
/// </summary>
|
||||
private static String decodeBase900toBase10(int[] codewords, int count)
|
||||
{
|
||||
BigInteger result = BigInteger.Zero;
|
||||
for (int i = 0; i < count; i++)
|
||||
{
|
||||
result = BigInteger.Add(result, BigInteger.Multiply(EXP900[count - i - 1], new BigInteger(codewords[i])));
|
||||
}
|
||||
String resultString = result.ToString();
|
||||
if (resultString[0] != '1')
|
||||
{
|
||||
return null;
|
||||
}
|
||||
return resultString.Substring(1);
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user
