2. Coding by using the Stack [10+10+10pt]

2.1 Early computers use a stack organization: heres how x = a - b is done:

push a # a is pushed onto stack

push b # b is pushed onto stack

Sub # pop out the top two number, performing # subtraction, and push the result back

Pop x # x = item pop from stack

Show how x = ( (a - b) * (c + d) ) / (e f ) can be done.

Suppose the available instructions are: push, pop, sub, add, mul, div.

2.2 A user defined stack with partially available information are shown below. Based on the provided clues, fill in its other operations.

a) .data

my_stack: .word 0, 0, 0, 0, 0, 0 ...

.text

#----- initialize stack pointer---

___________ ___________ ...

#----- pop from stack into $t1 ---

lw $t1, -4($t2) subi $t2, $t2, 4 ...

#----- push $t6s value onto stack

__________________ __________________

b) .data

my_stack: .byte -1, -1, -1, -1 ...

.text

# ---- initialize stack pointer---

_____________ _____________ ...

# ---- push $t2s value onto stack ---

addi $s1, $s1, 1 sb $t2, ($s1) ...

#----- pop from stack into $t5 --------

__________________ __________________

c) .data

my_stack: .word 1, 2, 3, 4, 5, 6, 7 ...

.text ... #----- pop from stack into $t1 ---

addi $s2, $s2, 4 lw $t1, -4($s2) ...

#----- push $t0s value onto stack

__________________ __________________

MUST BE IN MIPS ASSEMBLY