77 lines
2.5 KiB
C#
77 lines
2.5 KiB
C#
using System;
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namespace Cryville.Common.Pdt {
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/// <summary>
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/// PDT operator.
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/// </summary>
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public unsafe abstract class PdtOperator {
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byte* _prmem;
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int _loadindex;
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readonly PdtVariableMemory[] _operands;
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/// <summary>
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/// The count of the operands loaded.
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/// </summary>
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protected int LoadedOperandCount { get { return ParamCount - _loadindex; } }
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/// <summary>
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/// Gets the operand at the specified index.
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/// </summary>
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/// <param name="index">The index.</param>
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/// <returns>The operand at the specified index.</returns>
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/// <exception cref="IndexOutOfRangeException"><paramref name="index" /> is not less than <see cref="LoadedOperandCount" /> or less than 0.</exception>
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protected PdtVariableMemory GetOperand(int index) {
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if (index >= LoadedOperandCount || index < 0) throw new IndexOutOfRangeException();
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int i = index + _loadindex;
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return _operands[i];
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}
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internal int ParamCount { get; private set; }
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/// <summary>
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/// Creates an instance of the <see cref="PdtOperator" /> class.
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/// </summary>
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/// <param name="pc">The suggested parameter count.</param>
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protected PdtOperator(int pc) {
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ParamCount = pc;
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_operands = new PdtVariableMemory[pc];
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}
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PdtEvaluatorBase _etor;
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bool _failure = false;
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bool _rfreq = true;
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internal void Begin(PdtEvaluatorBase etor) {
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_etor = etor;
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_failure = false;
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_loadindex = ParamCount;
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}
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internal void LoadOperand(PdtVariableMemory mem) {
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if (_loadindex == 0) return;
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_operands[--_loadindex] = mem;
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}
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internal void Call(byte* prmem, bool noset) {
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_prmem = prmem;
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_rfreq = false;
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Execute();
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if (!_rfreq && !noset) throw new InvalidOperationException("Return frame not set");
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if (_failure) {
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if (_rfreq) _etor.DiscardStack();
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throw new InvalidOperationException("Evaluation failed");
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}
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}
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/// <summary>
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/// Executes the operator.
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/// </summary>
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protected abstract void Execute();
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/// <summary>
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/// Gets a return frame.
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/// </summary>
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/// <param name="type">The type of the frame.</param>
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/// <param name="len">The length of the frame.</param>
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/// <returns>The return frame.</returns>
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/// <exception cref="InvalidOperationException">The return frame has already been requested.</exception>
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protected PdtVariableMemory GetReturnFrame(int type, int len) {
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if (_rfreq) {
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_failure = true;
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throw new InvalidOperationException("Return frame already requested");
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}
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_rfreq = true;
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return _etor.StackAlloc(type, _prmem, len);
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}
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}
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} |