ese2.asm

num_pow2:
    addi $sp, $sp, -16      # alloco lo stack
    sw $ra, 12($sp)         # salvo $ra
    sw $s0, 8($sp)
    sw $s1, 4($sp)
    sw $s2, 0($sp)

    add $s0, $a0, $0        # $s0 = &A[0]
    add $s1, $0, $0         # $s1 = 0 = pow2_counter
    sll $s2, $a1, 2         # $s2 = m*4
    add $s2, $a0, $s2       # $s2 = ( &A[0] + (m*4) ) = &A[m]

for:    beq $s0, $s2, exit      # iff $s0 == &A[m] goto exit
    lw $a0, 0($s0)          # $a0 = A[i]
    jal pow2
    beq $v0, $0, else       # iff $v0 == 0 ==> A[i] non è una potenza di due
    addi $s1, $s1, 1        # iff $v0 != 0 ===> A[i] è una potenza di due e allora: pow2_counter++

else:   addi $s0, $s0, 4        # A++
    j for

exit:   add $v0, $0, $s1        # return $v0 = pow2_counter

    lw $s2, 0($sp)
    lw $s1, 4($sp)
    lw $s0, 8($sp)
    lw $ra, 12($sp)         # ripristino $ra
    addi $sp, $sp, 16       # dealloco stack
    jr $ra