1. # Merge Sort
# AdamTuckerand AmandaVerno
# Assignment#6 Problem
# Version12/09/2015
.data # Data declarationsection
_msg0: .asciiz"UnsortedArray"
_msg1: .asciiz"SortedArray"
_newline: .asciiz"n"
_spaces: .asciiz" "
Array1: .word 7 16 3 1 5 9 8 2 6 4
10 15 19 13 14 17 20 18 12 11
Array2: .word 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
.text
.globl main
main:
addi $sp, $sp, -4 # make roomon the stack for returnaddress
sw $ra, 0($sp) # save the returnaddress
#Load array address
la $a0, Array2 # addressof temparray
la $a1, Array1 # loadaddressof unsortedarray
addi $a2, $zero,20 # loadsize of array into$a2
and $a3, $zero,$zero # initializinglow =0
or $t0, $a1, $zero # addressof unsortedarray
or $t3, $a2, $zero # array length
#Printmessage
li $v0, 4 # systemcall code forprint_str
la $a0, _msg0 # addressof stringto print
syscall
#Printnewline
li $v0, 4 # systemcall code forprint_str
la $a0, _newline # addressof stringto print
syscall

2. and $t4, $zero,$zero # seti to 0
j LoopPrintUn # jumpto printunsortedarray
PrepSort:
addi $sp, $sp, -16 # make roomon the stack
sw $ra, 0($sp) # returnaddress
sw $a1, 8($sp) # save addressunsortedarray
add $a2, $a2, -1 # setting$a2 to (high - 1)
sw $a2, 4($sp) # save the size of the (array-1)
sw $a3, 0($sp) # low parameter
jal MSORT # jumpto merge sortwitharguments(array,high,low)
PrintSorted:
#Printnewline
li $v0, 4 # systemcall code forprint_str
la $a0, _newline # addressof stringto print
syscall # printthe string
#Printmessage
li $v0, 4 # systemcall code forprint_str
la $a0, _msg1 # addressof stringto print
syscall
#Printnewline
li $v0, 4 # systemcall code forprint_str
la $a0, _newline # addressof stringto print
syscall
and $t7, $zero,$zero # seti to 0
jal LoopPrintSort # jumpto printthe sortedarray
LoopPrintUn: # printunsortedarray
#While (i < length)
slt $t6, $t4, $a2 # if i < the lengthof the array
beq $t6, $zero,PrepSort # if (length<=i) thenjumptoprep formerge sort
# Load Array[i] andprintit
sll $t0, $t4, 2 # i * 4
add $t6, $a1, $t0 # base addressof array + offest

3. li $v0, 1 # systemcall code forprint_int
lw $a0, 0($t6) # shiftamountarray itme
syscall # printit
#Printspaces
li $v0, 4 # systemcall code forprint_str
la $a0, _spaces # addressof stringto print
syscall
addi $t4, $t4, 1 # i ++
j LoopPrintUn # loopprintforunsortedarray
LoopPrintSort: # printsortedarray
#While (i < length)
slt $t6, $t7, 20 # if i < the lengthof the array
beq $t6, $zero,EndProgram # if (length<=i) thenexitloop
sll $t0, $t7, 2 # i * 4
add $t6, $a1, $t0 # base addressof array + offest
li $v0, 1 # systemcall code forprint_int
lw $a0, 0($t6) # shiftamountarray itme
syscall # printarray [i]
#Printspaces
li $v0, 4 # systemcall code forprint_str
la $a0, _spaces # addressof stringto print
syscall
addi $t7, $t7, 1 # i ++
jal LoopPrintSort # loopprint
EndProgram:
addi $sp, $sp, 20 # popall itemsfromthe stack inmain
li $v0, 10 # END OFPROGRAM
syscall # END OFPROGRAM
MSORT:
addi$sp,$sp, -20 # make roomon the stack
sw $ra, 16($sp) # save returnaddress
sw $s1, 12($sp) # save argumentsunsortedarrayaddress
sw $s2, 8($sp) # save argumentssize of array= high

4. sw $s3, 4($sp) # save low size of array
sw $s4, 0($sp) # save registerformid
or $s1, $zero,$a1 # $s1 <- array address
or $s2, $zero,$a2 # $s2 <- size of array - 1 = high
or $s3, $zero,$a3 # $s3 <- low size
slt$t3, $s3, $s2 # low < high
beq$t3, $zero,DONE # if $t3 == 0, DONE
add $s4, $s3, $s2 # low + high
div$s4, $s4, 2 # $s4 <- (low+high)/2
or $a2, $zero, $s4 # argumentlow
or $a3, $zero, $s3 # argumentmid
jal MSORT # recursive call for(array,low,mid)
# mergesort(a,mid+1,high)
addi$t4, $s4, 1 # argumentmid+1
or $a3, $zero, $t4 # low gets(mid+1)
or $a2, $zero, $s2 # highgetshigh
jal MSORT # recursive call for(a,mid+1,high)
or $a1, $zero,$s1 # Argument1 getsarray address
or $a2, $zero,$s2 # Argument2 getshigh
or $a3, $zero,$s3 # Argument3 getslow
or $a0, $zero,$s4 # Argument4 getsmid
jal MERGE # jumpto merge (array,high,low,mid)
DONE:
lw $ra, 16($sp) # loadreturnaddress
lw $s1, 12($sp) # loadargumentsarray address
lw $s2, 8($sp) # loadargumentssize of array = high
lw $s3, 4($sp) # low size of array
lw $s4, 0($sp) # registerformid
addi $sp, $sp, 20 # clearroom onthe stack
jr $ra # jumpto register
MERGE:
addi$sp,$sp, -20 # make roomon the stack
sw $ra, 16($sp) # save returnaddress
sw $s1, 12($sp) # save argumentsunsortedarrayaddress
sw $s2, 8($sp) # save argumentssize of array= high
sw $s3, 4($sp) # save low size of array
sw $s4, 0($sp) # save registerformid
or $s1, $zero,$a1 # array address

5. or $s2, $zero,$a2 # $s2 <- size of array = high
or $s3, $zero,$a3 # $s3 <- low size
or $s4, $zero,$a0 # $s4 <- mid
or $t1, $zero, $s3 # i= $t1 getslow
or $t2, $zero, $s4 # j= $t2 getsmid
addi$t2, $t2, 1 # j= $t2 getsmid+ 1
or $t3, $zero, $a3 # k = low
WHILE:
slt $t4, $s4, $t1 # mid< i (i>=mid)
bne $t4, $zero,while2 # go to while 2if i >= mid
slt $t5, $s2, $t2 # high< j (j>=high)
bne $t5, $zero,while2 # && go to while 2if j >= high
sll $t6, $t1, 2 # i*4
add $t6, $s1, $t6 # $t6 = addressa[i]
lw $s5, 0($t6) # $s5 = a[i]
sll $t7, $t2, 2 # j*4
add $t7, $s1, $t7 # $t7 = addressa[j]
lw $s6, 0($t7) # $s6 = a[j]
slt $t4, $s5, $s6 # a[i] < a[j]
beq $t4, $zero,ELSE # go to else if a[i] >=a[j}
sll $t8, $t3, 2 # k*4
la $a0, Array2 # loadaddressof temporaryarray (neccasaryif using$a0 forprint
statements)
add $t8, $a0, $t8 # $t8 = addressc[k]
sw $s5, 0($t8) # c[k] = a[i]
addi $t3, $t3, 1 # k++
addi $t1, $t1, 1 # i++
j WHILE
ELSE:
sll $t8, $t3, 2 # i*4
la $a0, Array2 # # loadaddressof temporaryarray(neccasaryif using$a0 for print
statements)
add $t8, $a0, $t8 # $t8 = addressc[k]
sw $s6, 0($t8) # c[k] = a[j]
addi $t3, $t3, 1 # k++
addi $t2, $t2, 1 # j++
j WHILE
while2:

6. slt $t4, $s4, $t1 # mid< i (i>=mid)
bne $t4, $zero,while3 # go to while3if i >= mid
sll $t6, $t1, 2 # i*4
add $t6, $s1, $t6 # $t6 = addressa[i]
lw $s5, 0($t6) # $s5 = a[i]
sll $t8, $t3, 2 # i*4
la $a0, Array2 # loadaddressof temporaryarray (neccasaryif using$a0 forprint
statements)
add $t8, $a0, $t8 # $t8 = addressc[k]
sw $s5, 0($t8) # c[k] = a[i]
addi $t3, $t3, 1 # k++
addi $t1, $t1, 1 # i++
j while2
while3:
slt $t5, $s2, $t2 # high< j (j>=high)
bne $t5, $zero,start # go to forloopif j >= high
sll $t7, $t2, 2 # i*4
add $t7, $s1, $t7 # $t7 = addressa[j]
lw $s6, 0($t7) # $s6 = a[j]
sll $t8, $t3, 2 # i*4
la $a0, Array2 # loadaddressof temporaryarray (neccasary if using$a0 forprint
statements)
add $t8, $a0, $t8 # $t8 = addressc[k]
sw $s6, 0($t8) # c[k] = a[j]
addi $t3, $t3, 1 # k++
addi $t2, $t2, 1 # j++
j while3
start:
or $t1, $zero,$s3 # i <- low
forloop:
slt $t5, $t1, $t3 # i < k
beq $t5, $zero,DONE # branchif mergingiscomplete
sll $t6, $t1, 2 # i*4
add $t6, $s1, $t6 # $t6 = addressa[i]
sll $t8, $t1, 2 # i*4
la $a0, Array2 # loadaddressof temporaryarray (neccasaryif using$a0 forprint
statements)
add $t8, $a0, $t8 # $t8 = addressc[i]

7. lw $s7, 0($t8) # $s7 = c[i]
sw $s7, 0($t6) # a[i]
addi $t1, $t1, 1 # i++
j forloop