The following code is used to derive Fibonacci algorithm with this sequence: (0, 1, 1, 2, 3, 5, 8, 13, 21, …) where each number is “add” of two previous ones. int fib(int n){ if (n==0) return 0; else if (n == 1) return 1; else return fib(n−1) + fib(n−2); } Explain why the following RISC-V assembly code works, you need to explain all the details using the comments as hints?   # IMPORTANT! Stack pointer must remain a multiple of 16!!!!   addi x10,x10,8                # fib(8), you can change it fib: beq x10, x0, done             # If n==0, return 0 addi x5, x0, 1 beq x10, x5, done             # If n==1, return 1 addi x2, x2, -16              # Allocate 2 words of stack space sd x1, 0(x2)                  # Save the return address sd x10, 8(x2)                 # Save the current n addi x10, x10, -1             # x10 = n-1 jal x1, fib # fib(n-1) ld x5, 8(x2) # Load old n from the stack sd x10, 8(x2) # Push fib(n-1) onto the stack addi x10, x5, -2 # x10 = n-2 jal x1, fib # Call fib(n-2) ld x5, 8(x2) # x5 = fib(n-1) add x10, x10, x5 # x10 = fib(n-1)+fib(n-2)   # Clean up: ld x1, 0(x2) # Load saved return address addi x2, x2, 16 # Pop two words from the stack   done: jalr x0, 0(x1)

The following code is used to derive Fibonacci algorithm with this sequence: (0, 1, 1, 2, 3, 5, 8, 13, 21, …) where each number is “add” of two previous ones.

int fib(int n){

if (n==0)

return 0;

else if (n == 1)

return 1;

else

return fib(n−1) + fib(n−2);

}

Explain why the following RISC-V assembly code works, you need to explain all the details using the comments as hints?

# IMPORTANT! Stack pointer must remain a multiple of 16!!!!

1. addi x10,x10,8                # fib(8), you can change it
2. fib:
3. beq x10, x0, done             # If n==0, return 0
4. addi x5, x0, 1
5. beq x10, x5, done             # If n==1, return 1
6. addi x2, x2, -16              # Allocate 2 words of stack space
7. sd x1, 0(x2)                  # Save the return address
8. sd x10, 8(x2)                 # Save the current n
9. addi x10, x10, -1             # x10 = n-1

• jal x1, fib # fib(n-1)
• ld x5, 8(x2) # Load old n from the stack
• sd x10, 8(x2) # Push fib(n-1) onto the stack
• addi x10, x5, -2 # x10 = n-2
• jal x1, fib # Call fib(n-2)
• ld x5, 8(x2) # x5 = fib(n-1)
• add x10, x10, x5 # x10 = fib(n-1)+fib(n-2)

• # Clean up:
• ld x1, 0(x2) # Load saved return address
• addi x2, x2, 16 # Pop two words from the stack

• done:
• jalr x0, 0(x1)