69 lines
1.9 KiB
C#
69 lines
1.9 KiB
C#
//
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// Copyright (c) Antmicro
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//
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// Full license details are defined in the 'LICENSE' file.
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//
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using System;
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using System.Globalization;
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using System.Text;
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namespace TermSharp.Vt100
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{
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public sealed class ByteUtf8Decoder
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{
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public ByteUtf8Decoder(Action<string> charDecodedCallback)
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{
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this.charDecodedCallback = charDecodedCallback;
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utfBytes = new byte[4];
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utf8Decoder = Encoding.UTF8.GetDecoder();
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result = new char[4];
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}
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public void Feed(byte b)
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{
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if(currentCount == 0)
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{
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currentCount = GetUtf8ByteCount(b);
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}
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utfBytes[currentIndex++] = b;
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if(currentIndex == currentCount)
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{
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var utf16CharCount = utf8Decoder.GetChars(utfBytes, 0, currentCount, result, 0, true);
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var resultAsString = new string(result, 0, utf16CharCount);
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var textElements = StringInfo.GetTextElementEnumerator(resultAsString);
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while(textElements.MoveNext())
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{
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charDecodedCallback((string)textElements.Current);
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}
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currentCount = 0;
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currentIndex = 0;
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}
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}
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private static int GetUtf8ByteCount(byte leadingByte)
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{
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if(leadingByte < 128)
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{
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return 1;
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}
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if(((leadingByte ^ 0xC0) >> 5) == 0)
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{
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return 2;
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}
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if(((leadingByte ^ 0xE0) >> 4) == 0)
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{
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return 3;
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}
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return 4;
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}
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private int currentCount;
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private int currentIndex;
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private readonly byte[] utfBytes;
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private readonly Action<string> charDecodedCallback;
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private readonly char[] result;
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private readonly System.Text.Decoder utf8Decoder;
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}
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}
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