Assignment 0 - EECS 211

Assignment 0 - EECS 211

Problem 0
In this problem, you need to follow the steps in the following tutorial: https://justinmeiners.
github.io/lc3-vm/index.html. In the next assignments, we are going to edit this virtual processor, so make sure you can follow all the details in this tutorial.
Problem 1
In this problem, you are going to compile/assemble code and run it on the virtual LC3 processor. First, you need to download the LC3 assembler which can be found on this website:: http:
//highered.mheducation.com/sites/dl/free/0072467509/104652/lc3tools_v12.zip. Follow
the instructions in the README file (found inside the zip file) to install the LC3-tools. After
installation, you should find an executable called “lc3as” which is the assembler you should use to
convert the assembly codes to binary.
For each of the following assembly codes, convert them into a binary code (.bin file), open the the
symbol table file (the .sym file) to check the memory location of the data and labels, and then use
the virtual processor to run the binary code on the LC3 processor.
Listing 1: Assembly Code # 1
1 ;; Set R3 to R1 ^ R2
2 ;; i.e. OR( AND(NOT(R1),R2), AND(R1,NOT(R2)))
3 ;; i.e. NOT(AND(NOT(AND(NOT(R1),R2)),NOT(AND(R1,NOT(R2)))))
4 .ORIG x3000
5 xor NOT R1,R1
6 AND R3,R1,R2
7 NOT R1,R1
8 NOT R2,R2
9 AND R4,R1,R2
10 NOT R2,R2
11 NOT R3,R3
12 NOT R4,R4
13 AND R3,R3,R4
14 NOT R3,R3
15 HALT
1
Listing 2: Assembly Code # 2
1 ;; Reverse a string
2 .ORIG x3000
3 rev LEA R0,FILE ;; R0 is beginning of string
4 ADD R1,R0,#-1
5 LOOP1 LDR R3,R1,#1 ;; Note -- LDR "looks" at the word past R1
6 BRz DONE1
7 ADD R1,R1,#1
8 BR LOOP1
9
10 DONE1 NOT R2,R0
11 ADD R2,R2,R1
12
13 ;; R0 == address of first character of string
14 ;; R1 == address of last character of string
15 ;; R2 == size of string - 2 (Think about it....)
16 LOOP2 ADD R2,R2,#0
17 BRn DONE2
18 LDR R3,R0,#0 ;; Swap
19 LDR R4,R1,#0
20 STR R4,R0,#0
21 STR R3,R1,#0
22 ADD R0,R0,#1 ;; move pointers
23 ADD R1,R1,#-1
24 ADD R2,R2,#-2 ;; decrease R2 by 2
25 BR LOOP2
26
27 DONE2 HALT
28
29 FILE .STRINGZ "This is so much fun!"
30 .END
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Problem 2
Edit the virtual processor code to dump the memory and registers in a text file, every time the code
hits a “HALT”. That is, you need to debug the virtual processor code to know what happens when
the virtual processor tries to execute the “HALT” assembly command, and add a new function
there that dumps the current content of the memory and the registers into a text file. Below is a
snapshot of a file that dumps the first 5 locations of the memory and the first 4 registers (for this
assignment, you need to dump the entire memory and registers, this is just a small example):
1 M0 : 542
2 M1 : 12
3 M2 : 0
4 M3 : 11
5 M4 : 345
6 R0 : 12317
7 R1 : 12316
8 R2 : 65534
9 R3 : 111
Listing 1: Toy example for constraint satisfaction
Make sure that your file follows exactly the same format above, since we are going to automatically
grade the assignment by comparing your files to the correct answer.
Deliverable
You need to upload two files named “memory dump 1” and “memory dump 2” that contains the
memory/registers for the two assembly codes above.
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