9. Building Your Own Stack Machine

• Your assignment is to build a small command-based stack machine.

• Here is the minimal set of commands that your machine must understand:

      push N  ; PUSH( N )
      add     ; PUSH( POP() + POP() )
      hlt     ; HALT the machine
      start   ; START the machine
  

  where

  • PUSH command pushes decimal value N on the stack. If stack overflow condition is detected, the comand prints an appropriate error message and goes into a HALT state.

  • ADD command pops two values from the stack and computes their sum. The result is pushed back on the stack. If less than 2 values are present on the stack, the comand prints an error message and goes into a HALT state.

  • HLT command stops the execution and places the machine in the HALT state.

  • START command sets the instruction pointer to the first instruction, and switches the machine into a RUN state, which executes the loaded program.