LabD1Client : Translate Java class into MIPS (2)

# =====================  Java Code  ====================

public class FractionClient

{

public static void main(String[] args)

{

Fraction a = new Fraction(3,8);

Fraction b = new Fraction(1,2);

a.add(b);

System.out.print(a.getNumerator());

System.out.print('/');

System.out.print(a.getDenominator());

}

 }

# =================== MIPS =======================

LabD1Client.s

.text

#--------------------

main:

sw $ra, 0($sp)

addi $sp, $sp, -4

# to translate Fraction a = new Fraction(3,8);

# step 1: new Fraction(3,8)  the instance of Fraction is created in the heap memory, allocating 8 bytes for 2 int type properties

# step 2: the reference a = ; save the start address of the instance in the registrer $s0  

# Fraction a = new Fraction(3,8);

addi $a0, $0, 3

addi $a1, $0, 8

jal Fraction

add $s0, $0, $v0 # a = 

# Fraction b = new Fraction(1,2);

addi $a0, $0, 1

addi $a1, $0, 2

jal Fraction

add $s1, $0, $v0 # b = 

# a.getNumerator();

#  getNumerator does not take any parameter, why do we need to pass $a0 = $v0?

#  Because many instance of Fraction is created, and we want to retrive the numerator value of instance "a" not instance "b"

add $a0, $0, $s0

jal getNumerator

# a.add(b)

#  two instance is needed, instance of "a" and instance of "b"

#  so pass the address of those 2 instance

#  why not just passing the int variable???????

add $a0, $0, $s0

add $a1, $0, $s1

jal adding

# a.setNumerator(6)

# a.setDenominator(7)

add $a0, $0, $s0

addi $a1, $0, 6

jal setNumerator

addi $a1, $0, 7

jal setDenominator

# --------- return --------------------

addi $sp, $sp, 4

lw $ra, 0($sp)

jr $ra