CPU Virtualizator

This C-project simulate the Assmebly language by using simple instructions written in a file.cvm and executing its content.

Project files

project
│   Makefile
│
└───include
│       execute.h
│       print.h
│       read.h
│
└───src
        esegui.c
        leggi.c
        stampa.c
        vm.c

What do you need?

This project make use of the compiler gcc, so it is required before its usage. To install gcc:

MacOS:

1. Install Homebrew by using the following
   $ /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
2. brew install gcc

Linux: $ sudo apt-get install gcc

Windows: Install Cygwin from https://cygwin.com/

To correctly work, you must provide a correctly formatted .cvm file.

How to write a .cvm file

The file can contains all the following instructions and the number of lines must be specified as the first valid line. Every instruction must end with a ;. You are allowed to insert comments after ;.

The following is the list of command you can use to write a program.

Command name	Command number	First parameter	Second parameter	Description
HALT	0	-	-	terminate program
DISPLAY	1	0-31 (reg R0-R31)	-	print on stdout value of the registers (-1: all of them)
PRINT STACK	2	number	-	print on stdout stack values
PUSH	10	0-31 (reg R0-R31)	-	insert on the stack the value of the registry defined by pos, and increment the stack pointer. Terminate if stack overflow
POP	11	0-31 (reg R0-R31)	-	copy the value taken from the stack (after the decreasing) in the registry. Terminates if stack underflow
MOV	12	0-31 (reg R0-R31)	number	copy the value in the registry
CALL	20	pos	-	substitute instruction pointer with value in pos
RET	21	-	-	execute a call to a subroutine. Terminate if stack overflow
JMP	22	pos	-	return from a subroutine. Terminate if stack underflow
JZ	23	pos	-	substitute the value of the instruction pointer with the value in pos1 if the value of the registry in pos2 is 0
JPOS	24	pos	-	substitute the value of the instruction pointer with the value in pos1 if the value of the registry in pos2 is positive
JNEG	25	pos	-	substitute the value of the instruction pointer with the value in pos1 if the value of the registry in pos2 is negative
ADD	30	0-31 (reg R0-R31)	0-31 (reg R0-R31)	integer sum between registry value in pos1 and pos2. The result of the sum is copied in the registry identified by pos3. Terminate if aritmethic overflow or underflow
SUB	31	0-31 (reg R0-R31)	0-31 (reg R0-R31)	integer subtraction between registry value in pos1 and pos2. The result of the subtraction is copied in the registry identified by pos3. Terminate if aritmethic overflow or underflow
MUL	32	0-31 (reg R0-R31)	0-31 (reg R0-R31)	integer multiplication between registry value in pos1 and pos2. The result of the multiplication is copied in the registry identified by pos3. Terminate if aritmethic overflow or underflow
DIV	33	0-31 (reg R0-R31)	0-31 (reg R0-R31)	integer division between registry value in pos1 and pos2. The result of the division is copied in the registry identified by pos3. Terminate if aritmethic overflow or underflow or registry in pos2 is equal to 0

How to run the program?

Place yourself into the root folder of the projet and execute make. After that you can execute VM to perform the features below.

Features

Once a file.cvm correctly formatted is created, you can:

• Execute the program by using VM execute filename.cvm;
• Print the content of the file by using VM print filename.cvm.