Assume the following register contents: $t0 = 0xAAAAAAAA, $t1 = 0x12345678 For t

Question

Assume the following register contents:

                               $t0 = 0xAAAAAAAA,        $t1 = 0x12345678

For the register values shown above, what is the value of $t2 for the following sequence of instructions? sll     $t2, $t0, 24 or $t2, $t2, $t1

For the register values shown above, what is the value of $t2 for the following sequence of instructions? sll     $t2, $t0, 4 andi $t2, $t2, 1

For the register values shown above, what is the value of $t2 for the following sequence of instructions? srl    $t2, $t0, 3 andi $t2, $t2, 0xFFEF

Explanation / Answer

Assuming the register size to be 32 bit,

1)

sll means "Shift left logical", so, $t2 will contain value in $t0 left shifted by 24 bits.

sll     $t2, $t0, 24

So, $t2 = 0xAAAAAAAA << 24 = 0xAA000000

And then $t2 will contain "value in $t2 logical or with $t1".

or $t2, $t2, $t1

So, $t2 = 0xAA000000 OR 0x12345678 = 0xBA345678

2)

sll means "Shift left logical", so, $t2 will contain value in $t0 left shifted by 4 bits.

sll     $t2, $t0, 4

Sp $t2 = 0x12345678 << 4 = 0x23456780

andi is "bitwise and immediate".So $t2 will contain "value in $t2 logical and -1".

andi $t2, $t2, 1

$t2 = 0x23456780 and -1 = 0x23456780

3)

srl means "Shift right logical", so, $t2 will contain value in $t0 right shifted by 3 bits.

srl    $t2, $t0, 3

$t2 = 0x12345678 >> 3 = 0x2468ACF

andi is "bitwise and immediate".So $t2 will contain "value in $t2 logical and 0xFFEF".

andi $t2, $t2, 0xFFEF

$t2 = 0x2468ACF and 0xFFEF = 0x8ACF

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