/simulateISAwithPython

program simulates a simple CPU with basic arithmetic and bitwise operations.

Primary LanguagePython

CPU Simulation Program

Overview

This program simulates a simple CPU with basic arithmetic and bitwise operations. It initializes CPU registers with user-provided values and executes a series of instructions entered by the user. The program supports the following operations: mov, add, sub, mul, div, lshift, and rshift. It outputs the state of the CPU registers and memory before and after executing the instructions.

Initial Setup

  1. Register Initialization:
    • The program prompts the user to enter initial values for registers R0 to R7.
    • These values are stored in the CPU's registers and memory.

Instructions Supported

  • mov: Move an immediate value to a register.
  • add: Add an immediate value to the value in a source register and store the result in a destination register.
  • sub: Subtract an immediate value from the value in a source register and store the result in a destination register.
  • mul: Multiply the value in a source register by an immediate value and store the result in a destination register.
  • div: Divide the value in a source register by an immediate value, store the quotient in a destination register, and store the remainder in a special mul_result attribute.
  • lshift: Left shift the value in a source register by an immediate value and store the result in a destination register.
  • rshift: Right shift the value in a source register by an immediate value and store the result in a destination register.

Program Execution

  1. Instruction Entry:

    • The user enters program instructions line by line in the format <opcode> <dest_reg> <src_reg> <value>.
    • Instructions are added to the program until the user inputs 'e' to execute.

  2. Instruction Format Validation:

    • Instructions must have exactly four tokens: opcode, destination register, source register (or immediate value), and immediate value (or register).
    • Destination and source registers must start with 'R' and be followed by an integer index.

  3. Instruction Execution:

    • The CPU executes each instruction in the order entered.
    • If an invalid instruction is encountered, it is skipped with an error message.

Output

  • Register Values:

    • The program prints the values of all registers before and after program execution.
    • Values are displayed in both decimal and 32-bit binary format.

  • Memory Values:

    • The program prints the values stored in memory that are non-zero.
    • Values are displayed in both decimal and 32-bit binary format.

  • CPI (Clocks Per Instruction):

    • The program calculates and prints the CPI based on the number of instructions executed.

Example Usage

  1. Run the program.
  2. Enter initial register values (space-separated) for R0 to R7.
  3. Enter program instructions (e.g., add R1 R2 3). Input 'e' on a new line to execute.
  4. View the state of registers and memory before and after execution.
  5. View the calculated CPI.

Note

  • Division by zero is handled with an error message.
  • The program does not handle invalid opcodes or register indices gracefully and may terminate unexpectedly if such cases are encountered.

This program provides a basic simulation of a CPU and is intended for educational purposes to understand CPU operations and instruction execution.