CODEWITHSUNDEEP
mips
Quicksillver
Quicksillver

Reputation: 307

MIPS program, error address out of bounds

I'm trying to solve a small assignment question using MARS, but I keep getting this error. Is there something that I did wrong?

I'm getting the error at linenum 11: which is lw $t0, 0

Below is the code of my program.

.data

SOURCE: .word 0x0100
DEST: .word 0x0110




.text

lw $t0, 0
lw $t4 , -1 
lw $t5 , 0
lw $t6, 20
lw $t7, 32

VERY_START:

beq $t6,$zero,EXIT
addi $t6,$t6,-1
lw $t7,32

 la $t1,SOURCE
li $t2,1
li $s1,2


START:

and $t3, $t2 , $t1

beq $t4,-1,FIRST_LOOP


bne $t4,$t3,STORE
#bne is branch if not equal to.

add $t5 , $t5 , 1


addi $t7, $t7 , -1

beq $t7, $zero, VERY_START

# So we jump to the very start if we have 32 bits done.



sll  $t2, $t2 , 1

j START

STORE:



sb $t5,DEST($t2)
#dest needs to be defined (It is implicit according to the question)
# after storing , we need to increment $t0 so that we can store the next element a byte away from this one. so 
add $t0 , $t0 , 2



lw $t5,1

addi $t7, $t7 , -1

beq $t7, $zero, VERY_START

# So we jump to the very start if we have 32 bits done.



sll  $t2, $t2 , 1

j START

FIRST_LOOP:
# we populate t4 here
move $t4,$t3
j START


EXIT:
#we find the number of counts by simply dividing the current t0 with 2

div $t0, $s1
mflo $t0
# we move the quotient to t0..


move $a0,$t0
li $v0, 1
syscall

Upvotes: 1

Views: 9138

Answers (1)

Tim Biegeleisen
Tim Biegeleisen

Reputation: 520878

According to this reference, you are trying to load a literal into a register using lw, which is not allowed:

RAM access only allowed with load and store instructions

You have two choices:

Option 1

You can load into $t0 from temporary storage

var1: .word 0       # declare storage for var1; initial value is 0

      .text

      lw $t0, var1 # load contents of RAM location into register $t0:  $t0 = var1
...

Option 2

You can use li load immediate using a literal value

      li $t0, 0    #  $t0 = 0   ("load immediate")

You have this problem in several places in your code.

Upvotes: 1

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