Chapter 2, Problem 2.31E

Explanation of Solution

Corresponding MIPS instruction:

The corresponding MIPS instruction for the given C code is as follows:

#create a stack

fib: addi $sp, $sp, -12

#push the value of "$ra"

sw $ra, 8($sp)

#push the value of "$s0"

sw $s0, 4($sp)

#push the value of "$a0 (N)"

sw $a0, 0($sp)

#check "n > 0" and also check "n = 1"

bgt $a0, $0, check

#add "$v0 = 0 + 0"

add $v0, $0, $0

#jump to the "return" loop

j return

#$t0 = $0 + 1

check: addi $t0, $0, 1

#if n > 1, go to loop

bne $t0, $a0, loop

#$v0 = $0 + $t0

add $v0, $0, $t0

#jump to the "return" loop

j return

#$a0 = $a0 – 1

loop:subi $a0, $a0, 1

#call the function

jal fib

#$s0 = $v0 + $0

add $s0, $v0, $0

#$a0 = $a0 – 1

sub $a0, $a0, 1

#call the function

jal fib

#$v0 = $v0 + $s0

add $v0, $v0, $s0

#pop $a0

return: lw $a0, 0($sp)

#pop $s0

lw $s0, 4($sp)

#pop $ra

lw $ra, 8($sp)

#$sp = $sp + 12

addi $sp, $sp, 12

#return the caller

jr $ra

Explanation:

• Initially the “fib” loop create a stack then push the values into the stack...