LMC Emulator

LMC Emulator written in Rust

This emulator implements the instructions provided by Peter Higginson's LMC and York University's LMC Instruction Set.

Instructions set

Name	Instruction	Code	Description
Add	ADD XY	1XY	Adds the content of memory address XY to the accumulator
Subtract	SUB XY	2XY	Subtracts the content of memory address XY from the accumulator
Store	STA XY	3XY	Stores the accumulator's content in memory address XY
Load	LDA XY	5XY	Loads the content of memory address of XY into the accumulator
Branch	BRA XY	6XY	Branches to memory address XY unconditionally
Branch Zero	BRZ XY	7XY	Branches to memory address XY if accumulator is zero
Branch Positive	BRP XY	8XY	Branches to memory address XY if accumulator is positive
Input	INP	901	Takes user input and stores it in the accumulator
Output	OUT	902	Writes the content of the accumulator to shell
Halt	HLT	0	Halts the execution of the program
Data	DAT	-	Defines a data location or initializes memory (can include an optional initial value)

Usage

Initialize

cargo build

Compile a source file

./target/debug/lmc_emulator --build <filename>

Run the generated binary

./target/debug/lmc_emulator --run <filename>

Examples

Add two numbers

INP
STA 99
INP
ADD 99
OUT
HLT

Add three numbers

INP
STA 99
INP
ADD 99
STA 99
INP
ADD 99
OUT
HLT

Add/subtract

INP
STA FIRST
INP
ADD FIRST
OUT
INP
SUB FIRST
OUT
HLT
FIRST DAT

Multiply two numbers

INP
STA NUM1
INP
STA NUM2
LOOP LDA TOTAL
ADD NUM1
STA TOTAL
LDA NUM2
SUB ONE
STA NUM2
BRP LOOP
LDA TOTAL
SUB NUM1
STA TOTAL
OUT
HLT
NUM1 DAT
NUM2 DAT
ONE DAT 1
TOTAL DAT 0

Infinite loop

INPUT INP
OUT
BRA INPUT

Pre-defining data

LDA VARIABLE
STA 99
VARIABLE DAT 1

Find greater number

INP
STA FIRST
INP
STA SECOND
SUB FIRST
BRP HIGHER
LDA FIRST
BRA DONE
HIGHER LDA SECOND
DONE OUT
HLT
FIRST DAT
SECOND DAT

Triangular numbers

INP
STA INPUT
LOOP LDA NUMBER
ADD COUNTER
OUT
STA NUMBER
LDA COUNTER
ADD ONE
STA COUNTER
LDA INPUT
SUB COUNTER
BRP LOOP
HLT
COUNTER DAT 1
NUMBER DAT 0
ONE DAT 1
INPUT DAT

Count down

INP
LOOP OUT
STA COUNT
SUB ONE
STA COUNT
BRP LOOP
HLT
ONE DAT 1
COUNT DAT

Fibonacci series

INP
STA N
START LDA N
BRZ FINISH
LDA A
OUT
LDA B
ADD A
STA 99
LDA B
STA A
LDA 99
STA B
LDA N
SUB Y
STA N
BRA START
FINISH LDA N
HLT
N DAT
A DAT 0
B DAT 1
Y DAT 1