Convert from Java to MIPS

I have an exam in a days time, and I would really appreciate it if you guys can check an answer of mine. I have to convert a small piece of java code into a MIPS instruction, but no memos are available, and this is the first time I'm doing this sort of thing.

Here is the question :

While (save[i] != k) {
save[i] = v[i];
i=i+2;
} 

a) The code listed above is a high level Java program that assigns each second element of array v to the array save. Assuming that the assembler stores the base addresses of the arrays save and v respectively into registers $s2 and $s3, you are asked to convert the Java program above into an assembly language code. Note: You are free to use different registers for the variables which were not specified explicitly

And here's an attempt :

i = $t1

k = $t2

loop: sll $t3, $t1, 2 //get the offset (i*4) add $t4, $t3, $s2 //t4 is the address for save[i] beq $t4, $t2, exit //check the while condition add $t5, $t3, $s3 //t5 is the address for v[i] sw $t4, $t5 //save[i] = v[i] addi $t1, 2 //inc i j loop
exit:

Any help would be greatly appreciated.

EDIT: changed 'bne' to 'beq'

1 Answer

You're missing a couple of loads, and your store is incorrect:

sll $t3, $t1, 2 //get the offset (i*4)
add $t4, $t3, $s2 //t4 is the address for save[i]
lw $t5,($t4) //t5 = save[i]
beq $t5, $t2, exit //check the while condition
add $t5, $t3, $s3 //t5 is the address for v[i]
lw $t5,($t5) //t5 = v[i]
sw $t5, ($t4) //save[i] = v[i]
addi $t1, 2 //inc i