Question

Assume \(t0 holds the value 0x00101000. What is the value of \)t2 after the following instructions?

slt \(t2, \)0, \(t0

bne \)t2, \(0, ELSE

j DONE

ELSE: addi \)t2,$t2, 2

DONE:

Short answer

The value of $t2 after the execution of the given instructions is :

$t2=3

Step-by-step solution

Define MIPS decision making instructions

The instructions beq and bne are used to make decisions.

For example: beq register1,register2,L1

The instruction beq stands for “branch if equal”, which will go to the statement of the label specified if the register1 value is equal to register 2.

For example: bne register1,register2,L1

The instruction bne stands for “branch if not equal”, which will go to the labelled statement if register 1 value is not equal to register 2 value.

Determine the value of $t2.

Given MIPS instructions:

slt $t2, $0, $t0

bne $t2, $0, ELSE

j DONE

ELSE: addi $t2,$t2, 2

DONE:

In the above instruction, slt stands for “set on less than” . This instruction will compare the value $0 with the value of $t0. If the value $0 is less than The value of $t0, then the $t2 is set to 1.Here it is given that $t0 register has the value 0x00101000.

Now, if $0<0\times 00101000$then the value of $t2 is set to 1. Since 0 is less than the value of $t0 , now the value of $t2 is set to 1.

Instruction bne stands for “branch if not equal” . The values of $t2 and $0 is compared to check whether they are equal. Here, the value of $t2 is 1 and it is compared to 0, so they are not equal. So the ELSE part will be executed.

The ELSE part has the addi instruction that will add the value 2 to the value of $t2 and store the result in $t2.

We know that $t2=1, will be added to 2 and then the result 3 will be stored in $t2.

Now, $t2=3 after the execution of the given instructions.