Question

Variable Register a $9 b $19 c $2

C Operators + add - subtract & bitwise and ! bitwise or ~ bitwise not

Assume the variables, a, b and c are stored in the registers given above. Give a single MIPS assembly instruction from the MIPS Core Instruction Set that performs the equivalent operation for each of the following C

statements. a = ~ ( b | c ); // MIPS equivalent: --------

c = b - 2; // MIPS equivalent: ----------

b = a & 0x100F; // MIPS equivalent:----------

Answer 1

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1.a=~(b|c)

lw      $3,4($fp)

        lw      $2,8($fp)

        or      $2,$3,$2

        nor     $2,$0,$2

        sw      $2,0($fp)

2.c=b-2

lw      $2,4($fp)

        addiu   $2,$2,-2

        sw      $2,8($fp)

3.b = a & 0x100F

lw      $2,0($fp)

        andi    $2,$2,0x100f

        sw      $2,4($fp)