## - Fill in the five functions described below.

## - Modify only the function bodies. Do not modify any of the function

## names or other parts of this file.

## - All of your implementations should adhere to MIPS calling conventions.

## - When working correctly, your file should print out the following (one

## line of output for each question):

## Problem 1: 18 625 30

## Problem 2: 1 10 0

## Problem 3: 2 -1 -1 0

## Problem 4: 1 1 0

## Problem 5: 0 2 2 4

##

## Administrative Instructions

##

## - We will be testing your programs using QtSPIM

## - For download, from http://spimsimulator.sourceforge.net/

## - Documentation can be found here:

## http://spimsimulator.sourceforge.net/further.html

## - To turn in your code

##

## NB: The entire file is a single namespace, meaning your label names

## need to be globally unique.

##

#####################################################################

.data

newline: .asciiz " "

problem: .asciiz "Problem"

somechars: .asciiz "ABC?.3"

hello: .asciiz "hello"

world: .asciiz "world"

help: .asciiz "help"

vec1: .word 40, 100, 0

vec2: .word 40, 35, 47, 200, 43, 37, 31, 90, 62

vec3: .word -5, 0

vec4: .word 0

.text

.globl main

#####################################################################

## PROBLEM 1: weighted_avg

##

## Compute a weighted average of three 32-bit numbers, A, B, and C

## return (.25A + .25B + .5C)

## A,B, and C are in $a0, $a1, and $a2 respectively. The result

## should be returned in $v0.

##

## HINT: Do not use mult/div or floating point values. To keep

## precision for as long as possible, minimize the number of

## division operations.

#####################################################################

weighted_avg:

# YOUR CODE HERE

jr $ra

#####################################################################

## PROBLEM 2: min4

##

## Return the minimum, assuming unsigned integers, of $a0, $a1, $a2,

## and $a3 in $v0.

#####################################################################

min4:

# YOUR CODE HERE

jr $ra

#####################################################################

## PROBLEM 3: length

##

## Given a zero-terminated list of 4 byte integers ranging from 1-100

## (inclusive), count the number of elements in the list.

## - The terminating zero should not be included in the count.

## - If a value outside of legal range (1 >= x <= 100) is found

## indicate an error by returning -1.

## - Function takes one argument, a pointer to the start of the list

#####################################################################

length:

# YOUR CODE HERE

jr $ra

#####################################################################

## PROBLEM 4: diffchar

##

## Given two ASCII characters in $a0 and $a1, return

## - 1 if they are different

## - 0 if they are the same

#####################################################################

diffchar:

# YOUR CODE HERE

jr $ra

#####################################################################

## PROBLEM 5: hamming

##

## Compute the hamming distance (i.e., number of different characters)

## between two strings.

## - The two arguments are pointers to two null-terminated strings

## of characters.

## - If one string is shorter than the other, the mismatches all

## count as 1, e.g., hello

## help

## 00011 = hamming distance of 2

## - You should use your diffchar function from problem 4.

#####################################################################

hamming:

# YOUR CODE HERE

jr $ra

####################################################################

## DO NOT MODIFY BELOW THIS LINE ##

####################################################################

main:

########################################

## TEST PROBLEM 1 ##

########################################

li $a0, 1

jal print_problem_header

li $a0, 42

li $a1, 10

li $a2, 10

jal weighted_avg # weighted_avg = 18

move $a0, $v0

jal print_int

jal print_space

li $a0, 500

li $a1, 1000

li $a2, 500

jal weighted_avg # weighted_avg = 625

move $a0, $v0

jal print_int

jal print_space

li $a0, 30

li $a1, 31

li $a2, 30

jal weighted_avg # weighted_avg = 30

move $a0, $v0

jal print_int

jal print_newline

########################################

## TEST PROBLEM 2 ##

########################################

li $a0, 2

jal print_problem_header

li $a0, 1

li $a1, 10

li $a2, 100

li $a3, 1000

jal min4 # min4 = 1

move $a0, $v0

jal print_int

jal print_space

li $a0, 1000

li $a1, 10

li $a2, 100

li $a3, 1000

jal min4 # min4 = 10

move $a0, $v0

jal print_int

jal print_space

li $a0, 10

li $a1, 1

li $a2, 0

li $a3, 8

jal min4 # min4 = 0

move $a0, $v0

jal print_int

jal print_newline

########################################

## TEST PROBLEM 3 ##

########################################

li $a0, 3

jal print_problem_header

la $a0, vec1

jal length # length = 3

move $a0, $v0

jal print_int

jal print_space

la $a0, vec2

jal length # length = -1

move $a0, $v0

jal print_int

jal print_space

la $a0, vec3

jal length # length = -1

move $a0, $v0

jal print_int

jal print_space

la $a0, vec4

jal length # length = 0

move $a0, $v0

jal print_int

jal print_newline

########################################

## TEST PROBLEM 4 ##

########################################

li $a0, 4

jal print_problem_header

la $s0, somechars

la $a0, 42($a0)

la $a1, 1($s0)

jal diffchar # diffchar = 1

move $a0, $v0

jal print_int

jal print_space

la $a0, 4($s0)

la $a1, 5($s0)

jal diffchar # diffchar = 1

move $a0, $v0

jal print_int

jal print_space

la $a0, 2($s0)

la $a1, 2($s0)

jal diffchar # diffchar = 0

move $a0, $v0

jal print_int

jal print_newline

########################################

## TEST PROBLEM 5 ##

########################################

li $a0, 5

jal print_problem_header

la $a0, hello

la $a1, hello

jal hamming # hamming = 0

move $a0, $v0

jal print_int

jal print_space

la $a0, hello

la $a1, help

jal hamming # hamming = 2

move $a0, $v0

jal print_int

jal print_space

la $a0, help

la $a1, hello

jal hamming # hamming = 2

move $a0, $v0

jal print_int

jal print_space

la $a0, hello

la $a1, world

jal hamming # hamming = 4

move $a0, $v0

jal print_int

jal print_newline

########################################

## EXIT ##

########################################

li $v0, 10

syscall

####################################################################

## HELPER FUNCTIONS ##

####################################################################

print_problem_header:

addi $sp, $sp -8

sw $s0, 0($sp)

sw $ra, 4($sp)

move $s0, $a0

la $a0, problem

jal print_string

jal print_space

move $a0, $s0

jal print_int

li $a0, 58

jal print_char

jal print_space

lw $s0, 0($sp)

lw $ra, 4($sp)

addi $sp, $sp, 8

jr $ra

print_string:

li $v0, 4

syscall

jr $ra

print_char: li $v0, 11

syscall

jr $ra

print_int: li $v0, 1

syscall

jr $ra

print_space:

li $a0, 32

li $v0, 11

syscall

jr $ra

print_newline:

la $a0, newline

li $v0, 4

syscall

jr $ra

####################################################################

## END OF FILE ##

####################################################################