Package mars.mips.instructions

Class BasicInstruction

java.lang.Object
mars.mips.instructions.Instruction
mars.mips.instructions.BasicInstruction
public class BasicInstruction extends Instruction
Class to represent a basic instruction in the MIPS instruction set. Basic instruction means it translates directly to a 32-bit binary machine instruction.
Version:
August 2003
Author:
Pete Sanderson and Ken Vollmar

  • Constructor Details

    • BasicInstruction

      public BasicInstruction​(String example, String description, BasicInstructionFormat instrFormat, String operMask, SimulationCode simCode)
      BasicInstruction constructor.
      Parameters:
      example - An example usage of the instruction, as a String.
      instrFormat - The format is R, I, I-branch or J.
      operMask - The opcode mask is a 32 character string that contains the opcode in binary in the appropriate bit positions and codes for operand positions ('f', 's', 't') in the remaining positions.
      simCode - The inline definition of an object and class which anonymously implements the SimulationCode interface.
      See Also:
      SimulationCode

    • BasicInstruction

      public BasicInstruction​(String example, BasicInstructionFormat instrFormat, String operMask, SimulationCode simCode)

  • Method Details

    • getOperationMask

      public String getOperationMask()
      Gets the 32-character operation mask. Each mask position represents a bit position in the 32-bit machine instruction. Operation codes and unused bits are represented in the mask by 1's and 0's. Operand codes are represented by 'f', 's', and 't' for bits occupied by first, secon and third operand, respectively.
      Returns:
      The 32 bit mask, as a String

    • getInstructionFormat

      public BasicInstructionFormat getInstructionFormat()
      Gets the operand format of the instruction. MIPS defines 3 of these R-format, I-format, and J-format. R-format is all registers. I-format is address formed from register base with immediate offset. J-format is for jump destination addresses. I have added one more: I-branch-format, for branch destination addresses. These are a variation of the I-format in that the computed value is address relative to the Program Counter. All four formats are represented by static objects.
      Returns:
      The machine instruction format, R, I, J or I-branch.

    • getSimulationCode

      public SimulationCode getSimulationCode()
      Gets the SimulationCode object. It is really an object of an anonymous class that implements the SimulationCode interface. Such an object has but one method: Simulate().
      Returns:
      the SimulationCode object for this instruction.
      See Also:
      SimulationCode

    • getOpcodeMask

      public int getOpcodeMask()

    • getOpcodeMatch

      public int getOpcodeMatch()