High-level Language Programmer's View

main:

maxNum = 3

maxPower = 4

CalculatePowers(maxNum, maxPower)

(*)

. . .

end main

CalculatePowers(In: integer numLimit,

integer powerLimit)

integer num, pow, result

for num := 1 to numLimit do

for pow := 1 to powerLimit do

Power(num, pow, result)

(**) print num " raised to " pow " power is "

result

end for pow

end for num

end CalculatePowers

Power( In: integer n, integer e, Out: result)

if e = 0 then

result = 1

else if e = 1 then

result = n

else

Power(n, e - 1, result)

result = result * n (***)

end if

end Power

1) Trace the next execution of the recursive function Power by showing the run-time stack.

2) What is the most number of call frames on the stack at any one time for the whole program?

Assembly-language Programmer's View

3) Trace the hypothetical assembly language program and indicate the resulting value of the registers Reg1, Reg2, Reg3, and Reg4.

.data

X: .WORD 2 ; variable X initialized at assembly time to 2

Y: .WORD 3 ; variable Y initialized at assembly time to 3

Z: .WORD 0 ; variable Z initialized at assembly time to 0

.program

Begin:

LOAD Reg1, X ; loads X's value into register Reg1

LOAD Reg2, Y

ZERO Reg3 ; sets Reg3's value to 0

MOVE Reg4, Reg2 ; Reg4 := Reg2

Loop:

ADD Reg3, Reg3, Reg1 ; Reg3 := Reg3 + Reg1

SUB_IMMEDIATE Reg4, Reg4, #1 ; Reg4 := Reg4 - 1

BRANCH_GREATER_THAN_ZERO Reg4, Loop ; if Reg4 > 0 then goto Loop label

STORE Reg3, Z ; store Reg3's value into variable Z

End:

	Reg1	Reg2	Reg3	Reg4
Resulting register values

a) What is the resulting value in Z?

b) What calculation does this code perform?

4) During the execution of the above assembly language code: (Assuming no cache)

a) How many memory reads were performed? (state any assumptions)

# data reads =

# instruction reads (assume one read per instruction fetch) =

b) How many memory writes were performed? (state any assumptions)

5) List (in decreasing order of importance) why somebody would write assembly language code.

(top reason) a)

b)

c)