MIPS, SPIM

1. Computer Organization and Structure 2011
SPIM & MIPS
PROGRAMMING
Created and Presented by
Shu-Yang Lin, Hsun-Pei Wang,
Liang-Tsen Shen
Department of Information Management
National Taiwan University

2. OUTLINE
Homework 2
(Programming
MIPS – Assignment)
Assembly
SPIM – Language
Getting Programming
Introduction Started
to Assembly
Language

3. ASSEMBLY LANGUAGE
Machine language
• Computer’s binary encoding
Assembly language
• Symbolic representation of a computer’s binary
encoding
Assembler
• Translates assembly language into binary instructions

4. WHAT IS SPIM?
MIPS32 simulator that reads and executes
assembly language program written for
SPIM.
SPIM does NOT execute binary program.

5. REFERENCES OF SPIM
Official website of SPIM:
http://spimsimulator.sourceforge.net/
Assemblers, Linkers, and the SPIM
Simulator:http://pages.cs.wisc.edu/~larus/HP_Ap
pA.pdf
MIPS Instruction
Reference:http://www.mrc.uidaho.edu/mrc/peopl
e/jff/digital/MIPSir.html

6. QTSPIM - INSTALLATION
http://spimsimulator.sourceforge.net
/

7. QTSPIM - INSTALLATION
Linux
Windows
Mac

8. QTSPIM - SCREENSHOT Text Window
Register Window Data Window
Console Window

9. MIPS ASSEMBLY LANGUAGE
Operation Code (Opcode)

10. MIPS ASSEMBLY LANGUAGE
MIPS Registers and Usage Convention
n
 $zero constant 0
 $v0, $v1 expression of a function
 $a0~$a3 argument 1~4
 $t0~$t9 temporary registers
 $s0~$s7 save registers
 $sp stack pointer
 $fp frame pointer
 $ra return address
…

11. MIPS ASSEMBLY LANGUAGE
Some Data Types in MIPS
S
.word, .half • 32/16 bit integer
.byte • 8 bit integer
.ascii, .asciiz • string
.double, .float • floating point

12. MIPS SYSTEM CALLS
SPIM provides a small set of operating-system-
like services through the system call instruction.
A program loads the system call code into
register $v0 and arguments into registers $a0-
$a3 (or $f12 for floating-point values).
System calls that return values put their results
in register $v0 (or $f0 for floating-point results).

13. MIPS SYSTEM CALLS
$v0
FIGURE A.9.1 System services.

14. EXAMPLE – HELLO WORLD
C vs MIPS
int main() .data
{ Mystr: .asciiz “Hello World¥n”
printf(“Hello World¥”);
return 0; .text
main:
}
li $v0, 4
la $a0, Mystr
syscall
li $v0, 10
syscall

15. EXAMPLE – HELLO WORLD
MIPS Architecture
e
.data
Mystr: .asciiz “Hello World¥n”
Yourint: .word 75
Hisarray: .word 100, 100, 100
.word 20 , 40 , 60
.word 1 , 2 , 3
.text
……

16. EXAMPLE – HELLO WORLD
MIPS Architecture
e
.data
.text
main:
# do anything you want
……
# end of the program
li $v0, 10
syscall

17. MIPS SYSTEM CALLS - EXAMPLE
Output: “the answer = 5’’
.data
str:
.asciiz "the answer = "
.text
li $v0, 4 # system call code for print_str
la $a0, str # address of string to print
syscall # print the string
li $v0, 1 # system call code for print_int
li $a0, 5 # integer to print
syscall # print it
FIGURE A.9.1 System
services.

18. ASSEMBLER SYNTAX
Comment (#)
 Everything from the sharp sign to the end of the line is ignored.
Identifier (A sequence of alphanumeric characters, _ , and .)
 Identifier are a sequence of alphanumeric characters, underbars (_), and
dots (.) that do not begin with a number.
Instruction Opcode
 Instruction opcodes are reserved words that are not valid identifiers.
Label
 Labels are declared by putting them at the beginning of a line followed by a
colon.
PAGE 18

19. HOMEWORK

20. HOMEWORK
 This is an individual assignment
 Plagiarism will be heavily punished
 Write the following three programs in MIPS assembly
language. (Must run correctly on SPIM)
Simple Calculator
Star Pyramid
Pascal Triangle

21. DOCUMENTATION (20%)
 Detailed documentation for each program is required
 The following parts must be included:
 Your name, student ID, and email address
 Explanation of the design or the flow of each program
 What you’ve learnt from writing the programs
 Problems or difficulties you’ve encountered during writing
the programs are nice to be included in the document

22. PROBLEM 1. SIMPLE CALCULATOR
 Input:  Sample input / output
• Two integer x, y
( x, y may be positive, negative or
zero)
• An operator (+, ‐, *, /)
 Requirements:
• Print the correct answer.
• Can do many calculations
iteratively
• If the answer of division includes a
remainder please print it out
• The file name is Calculator.s

23. PROBLEM 2: STAR PYRAMID
 Build a pyramid using stars(*) and white spaces given
number of rows
Example:
Space # of rows = 5
4 *
3 * * *
2 * * * * *
1 * * * * * * *
* * * * * * * * *

24. PROBLEM 2: STAR PYRAMID
 Input:
 Number of rows of the pyramid: N
(N>0) Sample Input
 Requirements:
 Print the correct answer
(Number of white spaces and stars
should be correct)
 File Name: StarPyramid.s Sample Output
 Pyramid may seemed to be a little
inclined caused by the default display
settings of the console window in
QtSPIM  will NOT affect your score

25. PROBLEM 3: DEFORMATION OF PASCAL
TRIANGLE
F(m ,n) = F(m-1 ,n-1)+ 2*F(m-1 ,n) (F(x, 0)＝1
for all x and F(0, y)＝0 for y>0)
0 1 2 3 4 5 …
0 1 0 0 0 0 0 …
*2
1 1 1 0 0 0 0 …
*2 *2
2
1 3 1 0 0 0 …
*2 *2 *2
3
1 7 5 1 0 0 …
4 *2 *2 *2 *2
1 15 17 7 1 0 …

26. PROBLEM 3: DEFORMATION OF PASCAL
TRIANGLE
Input:
 Two integers m, n (m=1~20, n=1~99)
Requirements:
 Output F(m ,n) = F(m-1 ,n-1)+
2*F(m-1 ,n) (F(x, 0)＝1 for all x
and F(0, y)＝0 for y>0)
 Print the correct answer
 Can do many calculations iteratively
 File Name: PascalDeform.s

27. HOW TO EXECUTE MY PROGRAM USING QTSPIM?
Write your own assembly program, and
save it as .s file
Simulator  Clear Registers
Simulator Reinitialize Simulator
Open your .s file
Simulator  Run / Continue

28. SUBMISSION
 Deadline: 11:59pm, 1 Nov. (Tue.)
 You must submit at least the following files:
 Calculator.s
 StarPyramid.s
 PascalDeform.s
 (Your student id)_hwX_document.doc/pdf/docx
 Please put all your files in a directory named by your student id
in uppercase, and then compress it into one zipped file. (e.g.
zip/tgz …)
 You should upload your zipped file HW#2 to
https://filestork.net/suv6oro7 before the deadline.
 The file name should be like B99xxxxxx.zip, eg. B99705099.zip
 Rename your file for multiple uploads, eg. B99705099_v2.zip,
B99705099_v3.zip …

29. Remember to rename your file
SUBMISSION for multiple uploads!!!
https://filestork.net/suv6oro7
7

30. GRADING GUIDELINES
Description For Each Problem
Problem
Program runs without error messages 10%
Program executes correctly 60%
Documentation and description of
20%
the program
Implementation Detail 10%

31. CONTACT INFORMATION
TA Hours @ 管五 503-C
 Shu-Yang Lin (林書漾) Fri. 10:00~12:00
 Hsun-Pei Wang (王珣沛) Fri. 10:00~12:00
 Liang-Tsen Shen (沈亮岑) Mon. 10:00~12:00
Contact us if you have any problem
 林書漾 young@cmlab.csie.ntu.edu.tw
 王珣沛 garfieldduck@cmlab.csie.ntu.edu.tw
 沈亮岑 olga@cmlab.csie.ntu.edu.tw

32. DEADLINE
2011/11/1 (Tue.)
Late submission policy: 10% off from your total
score each day after the deadline

33. THANK YOU FOR
YOUR ATTENTION
Any Questions?