404 lines
11 KiB
C#
404 lines
11 KiB
C#
using System.Buffers;
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using System.Buffers.Binary;
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using System.Runtime.InteropServices;
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namespace System.Net.Sockets.Kcp
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{
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/// <summary>
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/// 调整了没存布局，直接拷贝块提升性能。
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/// <para>结构体保存内容只有一个指针，不用担心参数传递过程中的性能</para>
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/// https://github.com/skywind3000/kcp/issues/118#issuecomment-338133930
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/// <para>不要对没有初始化的KcpSegment(内部指针为0，所有属性都将指向位置区域) 进行任何赋值操作，可能导致内存损坏。
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/// 出于性能考虑，没有对此项进行安全检查。</para>
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/// </summary>
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public struct KcpSegment : IKcpSegment
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{
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internal readonly unsafe byte* ptr;
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public unsafe KcpSegment(byte* intPtr, uint appendDateSize)
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{
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this.ptr = intPtr;
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len = appendDateSize;
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}
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/// <summary>
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/// 使用完必须显示释放，否则内存泄漏
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/// </summary>
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/// <param name="appendDateSize"></param>
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/// <returns></returns>
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public static KcpSegment AllocHGlobal(int appendDateSize)
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{
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var total = LocalOffset + HeadOffset + appendDateSize;
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IntPtr intPtr = Marshal.AllocHGlobal(total);
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unsafe
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{
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///清零 不知道是不是有更快的清0方法？
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Span<byte> span = new Span<byte>(intPtr.ToPointer(), total);
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span.Clear();
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return new KcpSegment((byte*)intPtr.ToPointer(), (uint)appendDateSize);
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}
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}
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/// <summary>
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/// 释放非托管内存
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/// </summary>
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/// <param name="seg"></param>
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public static void FreeHGlobal(KcpSegment seg)
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{
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unsafe
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{
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Marshal.FreeHGlobal((IntPtr)seg.ptr);
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}
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}
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/// 以下为本机使用的参数
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/// <summary>
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/// offset = 0
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/// </summary>
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public uint resendts
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{
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get
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{
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unsafe
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{
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return *(uint*)(ptr + 0);
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}
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}
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set
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{
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unsafe
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{
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*(uint*)(ptr + 0) = value;
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}
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}
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}
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/// <summary>
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/// offset = 4
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/// </summary>
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public uint rto
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{
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get
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{
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unsafe
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{
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return *(uint*)(ptr + 4);
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}
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}
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set
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{
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unsafe
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{
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*(uint*)(ptr + 4) = value;
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}
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}
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}
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/// <summary>
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/// offset = 8
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/// </summary>
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public uint fastack
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{
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get
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{
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unsafe
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{
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return *(uint*)(ptr + 8);
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}
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}
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set
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{
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unsafe
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{
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*(uint*)(ptr + 8) = value;
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}
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}
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}
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/// <summary>
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/// offset = 12
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/// </summary>
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public uint xmit
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{
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get
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{
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unsafe
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{
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return *(uint*)(ptr + 12);
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}
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}
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set
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{
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unsafe
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{
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*(uint*)(ptr + 12) = value;
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}
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}
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}
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///以下为需要网络传输的参数
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public const int LocalOffset = 4 * 4;
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public const int HeadOffset = KcpConst.IKCP_OVERHEAD;
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/// <summary>
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/// offset = <see cref="LocalOffset"/>
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/// </summary>
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/// https://github.com/skywind3000/kcp/issues/134
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public uint conv
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{
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get
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{
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unsafe
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{
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return *(uint*)(LocalOffset + 0 + ptr);
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}
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}
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set
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{
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unsafe
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{
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*(uint*)(LocalOffset + 0 + ptr) = value;
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}
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}
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}
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/// <summary>
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/// offset = <see cref="LocalOffset"/> + 4
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/// </summary>
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public byte cmd
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{
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get
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{
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unsafe
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{
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return *(LocalOffset + 4 + ptr);
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}
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}
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set
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{
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unsafe
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{
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*(LocalOffset + 4 + ptr) = value;
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}
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}
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}
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/// <summary>
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/// offset = <see cref="LocalOffset"/> + 5
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/// </summary>
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public byte frg
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{
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get
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{
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unsafe
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{
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return *(LocalOffset + 5 + ptr);
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}
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}
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set
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{
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unsafe
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{
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*(LocalOffset + 5 + ptr) = value;
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}
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}
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}
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/// <summary>
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/// offset = <see cref="LocalOffset"/> + 6
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/// </summary>
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public ushort wnd
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{
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get
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{
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unsafe
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{
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return *(ushort*)(LocalOffset + 6 + ptr);
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}
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}
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set
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{
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unsafe
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{
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*(ushort*)(LocalOffset + 6 + ptr) = value;
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}
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}
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}
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/// <summary>
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/// offset = <see cref="LocalOffset"/> + 8
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/// </summary>
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public uint ts
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{
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get
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{
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unsafe
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{
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return *(uint*)(LocalOffset + 8 + ptr);
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}
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}
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set
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{
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unsafe
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{
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*(uint*)(LocalOffset + 8 + ptr) = value;
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}
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}
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}
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/// <summary>
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/// <para> SendNumber? </para>
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/// offset = <see cref="LocalOffset"/> + 12
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/// </summary>
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public uint sn
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{
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get
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{
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unsafe
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{
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return *(uint*)(LocalOffset + 12 + ptr);
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}
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}
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set
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{
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unsafe
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{
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*(uint*)(LocalOffset + 12 + ptr) = value;
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}
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}
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}
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/// <summary>
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/// offset = <see cref="LocalOffset"/> + 16
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/// </summary>
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public uint una
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{
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get
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{
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unsafe
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{
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return *(uint*)(LocalOffset + 16 + ptr);
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}
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}
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set
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{
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unsafe
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{
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*(uint*)(LocalOffset + 16 + ptr) = value;
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}
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}
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}
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/// <summary>
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/// <para> AppendDateSize </para>
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/// offset = <see cref="LocalOffset"/> + 20
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/// </summary>
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public uint len
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{
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get
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{
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unsafe
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{
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return *(uint*)(LocalOffset + 20 + ptr);
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}
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}
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private set
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{
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unsafe
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{
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*(uint*)(LocalOffset + 20 + ptr) = value;
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}
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}
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}
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/// <summary>
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///
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/// </summary>
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/// https://github.com/skywind3000/kcp/issues/35#issuecomment-263770736
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public Span<byte> data
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{
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get
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{
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unsafe
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{
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return new Span<byte>(LocalOffset + HeadOffset + ptr, (int)len);
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}
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}
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}
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/// <summary>
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/// 将片段中的要发送的数据拷贝到指定缓冲区
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/// </summary>
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/// <param name="buffer"></param>
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/// <returns></returns>
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public int Encode(Span<byte> buffer)
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{
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var datelen = (int)(HeadOffset + len);
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///备用偏移值 现阶段没有使用
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const int offset = 0;
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if (KcpConst.IsLittleEndian)
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{
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if (BitConverter.IsLittleEndian)
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{
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///小端可以一次拷贝
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unsafe
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{
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///要发送的数据从LocalOffset开始。
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///本结构体调整了要发送字段和单机使用字段的位置，让报头数据和数据连续，节约一次拷贝。
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Span<byte> sendDate = new Span<byte>(ptr + LocalOffset, datelen);
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sendDate.CopyTo(buffer);
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}
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}
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else
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{
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BinaryPrimitives.WriteUInt32LittleEndian(buffer.Slice(offset), conv);
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buffer[offset + 4] = cmd;
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buffer[offset + 5] = frg;
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BinaryPrimitives.WriteUInt16LittleEndian(buffer.Slice(offset + 6), wnd);
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BinaryPrimitives.WriteUInt32LittleEndian(buffer.Slice(offset + 8), ts);
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BinaryPrimitives.WriteUInt32LittleEndian(buffer.Slice(offset + 12), sn);
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BinaryPrimitives.WriteUInt32LittleEndian(buffer.Slice(offset + 16), una);
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BinaryPrimitives.WriteUInt32LittleEndian(buffer.Slice(offset + 20), len);
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data.CopyTo(buffer.Slice(HeadOffset));
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}
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}
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else
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{
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if (BitConverter.IsLittleEndian)
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{
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BinaryPrimitives.WriteUInt32BigEndian(buffer.Slice(offset), conv);
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buffer[offset + 4] = cmd;
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buffer[offset + 5] = frg;
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BinaryPrimitives.WriteUInt16BigEndian(buffer.Slice(offset + 6), wnd);
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BinaryPrimitives.WriteUInt32BigEndian(buffer.Slice(offset + 8), ts);
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BinaryPrimitives.WriteUInt32BigEndian(buffer.Slice(offset + 12), sn);
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BinaryPrimitives.WriteUInt32BigEndian(buffer.Slice(offset + 16), una);
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BinaryPrimitives.WriteUInt32BigEndian(buffer.Slice(offset + 20), len);
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data.CopyTo(buffer.Slice(HeadOffset));
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}
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else
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{
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///大端可以一次拷贝
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unsafe
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{
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///要发送的数据从LocalOffset开始。
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///本结构体调整了要发送字段和单机使用字段的位置，让报头数据和数据连续，节约一次拷贝。
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Span<byte> sendDate = new Span<byte>(ptr + LocalOffset, datelen);
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sendDate.CopyTo(buffer);
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}
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}
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}
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return datelen;
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}
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}
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}
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