1. The following MIPS function processes an array and returnstwo values in $v0 a

Question

1. The following MIPS function processes an array and returnstwo values in $v0 and

$v1. Assuming that the array consists of 5000 words indexed 0through 4999, and its base

address is stored in $a0 and its size (5000) in $a1, comment alllines and describe in a

sentence or two what this code does. Specifically, what will bereturned in $v0 and $v1?

add $a1, $a1, $a1 #

add $a1, $a1, $a1 #

add $v0, $zero, $zero #

add $t0, $zero, $zero #

outer: add $t4, $a0, $t0 #

lw $t4, 0($t4) #

add $t5, $zero, $zero #

add $t1, $zero, $zero #

inner: add $t3, $a0, $t1 #

lw $t3, 0($t3) #

bne $t3, $t4, skip #

addi $t5, $t5, 1 #

skip: addi $t1, $t1, 4 #

bne $t1, $a1, inner #

slt $t2, $t5, $v0 #

bne $t2, $zero, next #

add $v0, $t5, $zero #

add $v1, $t4, $zero #

next: addi $t0, $t0, 4 #

bne $t0, $a1, outer #

Explanation / Answer

The following MIPS function processes an array and returns twovalues in $v0 and

$v1. Assuming that the array consists of 5000 words indexed 0through 4999, and its base

address is stored in $a0 and its size (5000) in $a1, comment alllines and describe in a

sentence or two what this code does. Specifically, what will bereturned in $v0 and $v1?

add $a1, $a1, $a1#                  a1=10000

add $a1, $a1, $a1#                  a1=20000           (byte index into array)

add $v0, $zero, $zero#             v0=0

add $t0, $zero, $zero#              t0=0

outer: add $t4, $a0, $t0#            t4=address of element up to in array starts at array[0] and goes toend

lw $t4, 0($t4)#                           t4=array[t4]   get next element of array

add $t5, $zero, $zero#                t5=0

add $t1, $zero, $zero#               t1=0

inner: add $t3, $a0, $t1#            t3=address of element up to in array always starts at 1stelement

lw $t3, 0($t3)#         t3=array[t3] also starts at array[0], but keeps getting nextelement each time through inner loop

bne $t3, $t4, skip#                     array[t3]!=array[t4] go to skip    otherwise nextinstruction

addi $t5, $t5, 1#                        t5++

skip: addi $t1, $t1, 4#               t1+=4    index of next element ofarray

bne $t1, $a1, inner#                   t1!=a1 done going through array? no go toinner   yes continue

slt $t2, $t5, $v0#                       t5<v0 yes t2=1 otherwise t2=0     if t5 <v0 will go to next   otherwise willcontinue

bne $t2, $zero, next#                   t5<v0   go tonext      

add $v0, $t5, $zero#                  v0=t5                counter how many times elements equal

add $v1, $t4, $zero#                   v1=t4                value of array

next: addi $t0, $t0, 4#                   go to next element of array   (add 4 to index)

bne $t0, $a1, outer#                     done with array? if yes exit, otherwise go to outer

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