Assembly Intro

Introduction to MVM Assembly Language

This page provides a gentle introduction to the MVM (Micro Virtual Machine) assembly language. MVM assembly is a low-level language designed for a simple, time-sharing virtual machine. It allows you to write programs by providing a set of instructions that manipulate data stored in registers and memory. The virtual machine manages multiple processes concurrently.

Basic Concepts

• Registers: The MVM uses several types of registers:
  • General Purpose Registers (G1-G10): Used for general computations and data storage.
  • System Registers (S1-S4): Used for passing arguments to system calls. S1 holds the system call ID.
  • Return Registers (R1-R10): Used to store the results of operations and system calls.
  • Function Argument Registers (F1-F10): Used for passing arguments to functions.
  • Floating-Point Registers (X1-X10): Used for floating-point arithmetic.
  • Intel Registers (I1-I10): Hold status flags and other information.
• Memory: The MVM has a fixed amount of memory, accessed using addresses. Each address holds a 64-bit integer.
• Stack: A last-in, first-out (LIFO) data structure for temporary storage. Used for function calls return values.
• Instructions: Instructions specify operations. Each instruction has a mnemonic (e.g., ADD, MOV) and arguments (operands).
• System Calls: Functions to interact with the operating system (OS plus Kernel), such as file I/O, process management, and more. These are invoked using the SYSCALL instruction, which takes the system call ID as an argument.

Example Program

This simple program adds two numbers and prints the result:

LIT G1 10      // Load 10 into G1
LIT G2 5       // Load 5 into G2
ADD G1 G2 R1   // Add G1 and G2; result in R4
PRINTR R1      // Print the value in R4 (15)

Key Instruction Categories

• Data Transfer: LIT, XLIT, MOV, STORE, LOAD, PUSH, POP, PEEK, CPY, SETTYPE, DEALLOC
• Arithmetic: ADD, SUB, MUL, DIV, MOD, POW,
• Bitwise: AND, OR, XOR, NOT, SHL, SHR
• XFloats: XADD, XSUB, XMUL, XDIV, XMOD, XPOW, ITOF, FTOI
• Control Flow: JMP, JZ, JNZ, CALL, RET
• String: STR
• I/O: PRINTS, PRINTR
• System Calls: SYSCALL
• Miscellaneous: INR, HELP, SLEEP

Further Learning

For detailed information, refer to:

• Instruction Set: Detailed explanation of each instruction.
• Registers: Information on the different register types.
• Memory Model: How memory is organised and accessed.
• System Calls: How to interact with the OS kernel.
• Standard Library: Overview of available functions.

This introduction provides a foundation for understanding the MVM assembly language. You can start writing programs after understanding the basic concepts and then explore more advanced features.