Homework 4 Solution
cs345

1. Multi-part

a) #assume the declaration of the following string
    xGTEy: .asciiz "x is greater than or equal to y\n"

    #assume x is in $t1 and y is in $t2
    sge $t3, $t1, $t2
    beq $t3, $zero, endif
    li $v0, 4
    la $a0, xGTEy
    syscall
    endif:

b) #assume the declaration of the following string
    xLTz: .asciiz "x is less than z\n”

    #assume x is in $t1, y is in $t2, and z is in $t3
    slt $t4, $t1, $t2
    slt $t5, $t2, $t3
    and $t6, $t4, $t5
    beq $t6, $zero, endif
      li $v0, 4
      la $a0, xLTz
      syscall
    endif:

c) #assume the declaration of the following strings
    xGTz: .asciiz "x might be greater than z\n"
    xGLTyz: .asciiz "x is greater than or equal to y and less than z\n"

    #assume x is in $t1, y is in $t2, and z is in $t3
    slt $t4, $t1, $t2
    sge $t5, $t1, $t3
    or $t6, $t4, $t5

    beq $t6, $zero, else  #branch to else
      li $v0, 4
      la $a0, xGTz
      syscall
      b endif  #always branch to endif
    else:
      li $v0, 4
      la $a0, xGLTyz
      syscall
    endif:


d)  #assume the declaration of the following strings
    lessThanOrEq: .asciiz " is less than or equal to "
    asIs: .asciiz " as is "
    newLine: .asciiz "\n"

    #assume x is in $s1, y is in $s2, and z is in $s3
    add $t1, $s1, $s2  #x + y
    mul $t2, $s1, $s2  #x * y
    
    sle $t4, $t1, $s3  #x + y <= z
    sle $t5, $t2, $s3  #x * y <= z
    and $t6, $t4, $t5  #x+y <= z && x*y <= z

    beq $t6, $zero, endif

    li $v0, 1    #print x+y
    move $a0, $t1
    syscall

    li $v0, 4    #print a string
    la $a0, lessThanOrEq
    syscall

    li $v0, 1    #print z
    move $a0, $s3
    syscall 

    li $v0, 4   #print "as is"
    la $a0, asIs
    syscall

    li $v0, 1  # print x*y
    move $a0, $t2
    syscall

    li $v0, 4  #print newLine
    la $a0, newLine
    syscall

    endif:

2. Multi-part question

a) sub $s2, $t3, $t5

000000 01011 01101 10010 00000 100010
opcode rs    rt    rd    shamt  funct

0000 0001 0110 1101 1001 0000 0010 0010
0x016d9022

b) addi $t1, $s2, 127

001000 10010 01001 0000 0000 0111 1111
opcode rs    rt    immediate

0010 0010 0100 1001 0000 0000 0111 1111

0x2249007f

c) lw $s3, 12($s4)

100011 10100 10011 0000 0000 0000 1100 
opcode rs    rt    immediate

1000 1110 1001 0011 0000 0000 0000 1100 

0x8e93000c

d) or $t3, $t4, $t5

000000 01100 01101 01011 00000 100101
opcode rs    rt    rd    shamt funct

0000 0001 1000 1101 0101 1000 0010 0101

0x018d5825

3. #AreaCalculator.asm
#
#A program to compute the area of a triangle or a rectangle
#Inputs: 1 for a triangle and 2 for a rectangle
#        The length of the side of a square or the circle radius

.data
inputPrompt: .asciiz "Enter 1 for triangle 2 for rectangle: "
trianglePrompt: .asciiz "Enter the base and height of the triangle: "
rectanglePrompt: .asciiz "Enter the height and width of the rectangle: "
incorrectInput: .asciiz "Invalid input\n"
outputData: .asciiz "The area is "
newline: .asciiz "\n"
two: .double 2.0

.text
main:

#Prompt user for input
la $a0, inputPrompt
li $v0, 4
syscall

#Read an integer
la $v0, 5
syscall
move $t1, $v0

#triangle
#if t1 == 1
beq $t1, 2, elseif
bne $t1, 1, else

  #prompt for triangle
  la $a0, trianglePrompt
  li $v0, 4
  syscall

  l.d $f4, two

  #read base into $f0
  li $v0, 7
  syscall

  mov.d $f2, $f0

  #read height into $f0
  li $v0, 7
  syscall

  #compute and print area
  la $a0, outputData
  li $v0, 4
  syscall

  mul.d $f12, $f2, $f0
  div.d $f12, $f12, $f4
  li $v0, 3
  syscall 

  la $a0, newline
  li $v0, 4
  syscall
  
  b endif
elseif:

  #prompt for rectangle
  la $a0, rectanglePrompt
  li $v0, 4
  syscall

  #read height into $f0
  li $v0, 7
  syscall

  mov.d $f2, $f0

  #read width into $f0
  li $v0, 7
  syscall

  #compute and print area
  la $a0, outputData
  li $v0, 4
  syscall

  mul.d $f12, $f0, $f2
  li $v0, 3
  syscall 

  la $a0, newline
  li $v0, 4
  syscall
  j endif
else:
  la $a0, incorrectInput
  li $v0, 4
  syscall
endif:

#end program
li $v0, 10
syscall

4. Multi-part answer

a) #assume the following constants
  const1: .double 0.332
  #assume x is $f2

  l.d $f0, const1
  add.d $f2, $f2, $f0

b) #assume the following constants
  const1: .double 31.02
  const2: .double 6.2
  #assume x is in $f2, and y is in $f4

  l.d $f0, const1
  l.d $f6, const2

  mul.d $f6, $f6, $f4 #6.2*y
  sub.d $f6, $f6, $f2 #6.2*y - x
  div.d $f4, $f6, $f0 #(6.2*y - x) * 31.02

c) #assume the following constants
  one: .double 1.0
  four: .double 4.0
  three: .double 3.0
  five: .double 5.0
  #assume z is in $f2

  l.d $f4, one
  l.d $f6, four
  l.d $f8, three
  l.d $f10, five

  div.d $f10, $f10, $f8 # 5.0/3.0
  mul.d $f10, $f10, $f6 # 5.0/3.0*4.0
  add.d $f2, $f10, $f4  # 4.0/3.0*4.0+1.0

d) #assume the following constants
  const1: .float 4.13

  #assume f is in $f0, a is in $f2, b is in $f4, and c is in $f6

  l.s $f8, const1  #load const1
  cvt.d.s $f10, $f8 #convert const1 to a double
  mul.d $f0, $f4, $f6  #b * c
  div.d $f0, $f0, $f10 #b * c / 4.13
  add.d $f0, $f0, $f2  #a + b * c / 4.13
  
5. Multi-part question

a) x < y && y < z
Assume x is $t1, y is $t2, and z is $t3

slt $t4, $t1, $t2
slt $t5, $t2, $t3
and $t6, $t4, $t5

b) x <= y || y <= z
Assume x is $t1, y is $t2, and z is $t3

sle $t4, $t1, $t2
sle $t5, $t2, $t3
or $t6, $t4, $t5

c) x | y & z
Assume x is $t1, y is $t2, and z is $t3

and $t4, $t2, $t3
or $t5, $t1, $t4

d) (a + b) < (c / d)
Assume a is $t1, b is $t2, c is $t3, and d is $t4

add $t5, $t1, $t2
div $t6, $t3, $t4
slt $t7, $t6, $t5