56 lines
1.7 KiB
C#
56 lines
1.7 KiB
C#
namespace EMU7800.Core
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{
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/// <summary>
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/// Frames are composed of <see cref="BufferElement"/>s,
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/// that group bytes into machine words for efficient array processing.
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/// Bytes are packed in logical little endian order.
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/// </summary>
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public struct BufferElement
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{
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/// <summary>
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/// The number of bytes contained within a <see cref="BufferElement"/>.
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/// </summary>
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public const int SIZE = 4; // 2^SHIFT
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/// <summary>
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/// The mask value applied against a byte array index to access the individual bytes within a <see cref="BufferElement"/>.
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/// </summary>
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public const int MASK = 3; // SIZE - 1
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/// <summary>
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/// The left shift value to convert a byte array index to a <see cref="BufferElement"/> array index.
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/// </summary>
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public const int SHIFT = 2;
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uint _data;
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/// <summary>
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/// A convenience accessor for reading/writing individual bytes within this <see cref="BufferElement"/>.
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/// </summary>
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/// <param name="offset"></param>
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public byte this[int offset]
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{
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get
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{
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var i = (offset & MASK) << 3;
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return (byte)(_data >> i);
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}
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set
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{
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var i = (offset & MASK) << 3;
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var d = (uint)value << i;
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var di = (uint)0xff << i;
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_data = _data & ~di | d;
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}
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}
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/// <summary>
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/// Zeros out all bytes of this <see cref="BufferElement"/>.
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/// </summary>
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public void ClearAll()
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{
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_data = 0;
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}
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}
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}
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