GoldenCrystal
93 lines
3.7 KiB
C#
93 lines
3.7 KiB
C#
using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace System.Unicode.Builder
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{
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internal static class BinaryWriterExtensions
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{
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public static void WriteUInt24(this BinaryWriter writer, int value)
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{
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if (value < 0 || value > 0xFFFFFF) throw new ArgumentOutOfRangeException(nameof(value));
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writer.Write((byte)(value));
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writer.Write((byte)(value >> 8));
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writer.Write((byte)(value >> 16));
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}
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/// <summary>Writes code point in a custom, but compact encoding.</summary>
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/// <remarks>
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/// Unlike UTF-8, this encoding will consume at most 3 bytes.
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/// It could ideally store values between 0x0 and 0x40409F, but this range is useless at the moment.
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/// </remarks>
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/// <param name="writer">The binary writer to use.</param>
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/// <param name="value">The value to write</param>
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public static void WriteCodePoint(this BinaryWriter writer, int value)
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{
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if (value < 0 || value > 0x40407F) throw new ArgumentOutOfRangeException(nameof(value));
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if (value < 0xA0) writer.Write((byte)value);
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else if (value < 0x20A0)
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{
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value -= 0xA0;
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writer.Write((byte)((byte)(value >> 8) | 0xA0));
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writer.Write((byte)value);
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}
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else if (value < 0x40A0)
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{
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value -= 0x20A0;
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writer.Write((byte)((byte)(value >> 8) | 0xC0));
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writer.Write((byte)value);
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}
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else
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{
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value -= 0x40A0;
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writer.Write((byte)((byte)(value >> 16) | 0xE0));
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writer.Write((byte)(value >> 8));
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writer.Write((byte)value);
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}
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}
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/// <summary>Writes a character name alias.</summary>
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/// <remarks>We assume that character names will not exceed 64 bytes in length.</remarks>
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/// <param name="writer">The writer to use.</param>
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/// <param name="nameAlias">The name alias value to write.</param>
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public static void WriteNameAliasToFile(this BinaryWriter writer, UnicodeNameAlias nameAlias)
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{
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// This method will stuff two extra bits together with the byte count, provided that this one doesn't exceed 64.
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var bytes = Encoding.UTF8.GetBytes(nameAlias.Name);
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if (bytes.Length > 64) throw new InvalidOperationException("Did not expect UTF-8 encoded name aliases to be longer than 64 bytes.");
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writer.WritePackedLength((byte)(nameAlias.Kind - 1), nameAlias.Name.Length);
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writer.Write(bytes);
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}
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/// <summary>Writes a character name, packing two information bits along with the length.</summary>
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/// <remarks>We assume that character names will not exceed 128 bytes in length.</remarks>
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/// <param name="writer">The writer to use.</param>
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/// <param name="name">The name to write.</param>
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public static void WriteNamePropertyToFile(this BinaryWriter writer, string name)
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{
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var bytes = Encoding.UTF8.GetBytes(name);
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if (bytes.Length > 128) throw new InvalidOperationException("Did not expect UTF-8 encoded name to be longer than 128 bytes.");
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writer.Write((byte)(name.Length - 1)); // The most significant bit will always be cleared, because it will be used for other cases.
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writer.Write(bytes);
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}
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/// <summary>Writes a 6 bits length packed with two extra bits.</summary>
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/// <remarks>The parameters have a restricted range, which must be respected.</remarks>
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/// <param name="writer">The writer used to perform the operation.</param>
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/// <param name="extraBits">The value of the two extra bits.</param>
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/// <param name="length">The length to write.</param>
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public static void WritePackedLength(this BinaryWriter writer, byte extraBits, int length)
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{
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if (extraBits > 3) throw new ArgumentOutOfRangeException(nameof(extraBits));
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if (length < 1 || length > 64) throw new ArgumentOutOfRangeException(nameof(length));
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writer.Write((byte)((extraBits << 6) | (length - 1)));
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}
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}
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}
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