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InstructionType.cs
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InstructionType.cs
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// ------------------------------------------------------------------------------------------------------------------------
// File name: InstructionType.cs
// Project name: ISA
// Project description: Decoder for our awesome Detached-Toe 16-bit RISC ISA.
// ------------------------------------------------------------------------------------------------------------------------
// Creation Date: 03/31/2021
// ------------------------------------------------------------------------------------------------------------------------
namespace ISA_Decoder_16Bit {
/// <summary>
/// For determining the operations.
/// </summary>
abstract class InstructionType {
protected int InstructionTypeID;
protected int opcodeStartBit;
protected int opcode;
protected Operation operation;
/// <summary>
///
/// </summary>
/// <param name="inputBits">instruction bits</param>
/// <returns>string representation of ISA code.</returns>
public string DecodeInstruction(int inputBits) {
// (1) Determine opcode
operation = DecodeOpcode(inputBits);
// (2) Decode operation and get text.
return operation.DecodeOperation(inputBits);
}
/// <summary>
/// Get the opcode.
/// </summary>
/// <param name="inputBits">instruction bits</param>
/// <returns>Operation</returns>
public Operation DecodeOpcode(int inputBits) {
// Get mask for opcode + InstructionID
opcode = inputBits & BitUtilities.CreateBitMask(opcodeStartBit, 15);
switch (opcode) {
case (int)opcodeIdentificationHexLiterals.hexADD:
return new ADDoperation();
case (int)opcodeIdentificationHexLiterals.hexADC:
return new ADCoperation();
case (int)opcodeIdentificationHexLiterals.hexSUB:
return new SUBoperation();
case (int)opcodeIdentificationHexLiterals.hexMUL:
return new MULoperation();
case (int)opcodeIdentificationHexLiterals.hexDIV:
return new DIVoperation();
case (int)opcodeIdentificationHexLiterals.hexMOD:
return new MODoperation();
case (int)opcodeIdentificationHexLiterals.hexAND:
return new ANDoperation();
case (int)opcodeIdentificationHexLiterals.hexOR:
return new ORoperation();
case (int)opcodeIdentificationHexLiterals.hexNOT:
return new NOToperation();
case (int)opcodeIdentificationHexLiterals.hexNAND:
return new NANDoperation();
case (int)opcodeIdentificationHexLiterals.hexJMP:
return new JMPoperation();
case (int)opcodeIdentificationHexLiterals.hexJC:
return new JCoperation();
case (int)opcodeIdentificationHexLiterals.hexCMP:
return new CMPoperation();
case (int)opcodeIdentificationHexLiterals.hexNOP:
return new NOPoperation();
case (int)opcodeIdentificationHexLiterals.hexLOAD:
return new LOADoperation();
case (int)opcodeIdentificationHexLiterals.hexSTOR:
return new STORoperation();
default:
throw new System.Exception("Invalid Opcode.");
}
}
}
}