LAE 19 Oral Recursion

# int f ( int x ) {
#   if ( x < 2 ) return x + 3;
#    else return f ( x / 3 ) + f ( x - 4 );
# }
#

.data
    par: .word 3

.text
    main:
        lw $a0,par
        jal f

        j exit
    end_main:


    f:
        add $sp, $sp, -12
        sw $a0, 0($sp)
        sw $ra, 4($sp)

        bge $a0, 2, caso_ricorsivo
        blt $a0, 2, caso_base

        caso_ricorsivo:
            # x / 3
            div $a0, $a0, 3
            mflo $a0

            # f ( x / 3 )
            jal f
            lw $t0, -4($sp)

            # Ripristiniamo il parametro
            lw $a0, 0($sp)
            sub $a0, $a0, 4

            jal f
            lw $t1, -4($sp)

            add $t0, $t0, $t1
            sw $t0, 8($sp)
            lw $ra, 4($sp)
            add $sp, $sp, 12
            jr $ra

        caso_base:
            add $a0, $a0, 3
            sw $a0, 8($sp)
            add $sp, $sp, 12
            jr $ra

exit: