Assignment

$-$

Reverse String

Problem Statement: Create a Legv

$8$

program that reverses the characters in a string. The program should handle strings stored in memory and reverse the order of characters in place.

Requirements

Input:

The program should begin with a predefined string stored in memory. Choose a string that is a mix of characters, including spaces and punctuation, with a length of at least

$1$

$5$

characters.

Clearly define the starting address of the string in the program.

Process:

Develop the assembly code to reverse the string in place, without using additional memory to store the reversed string.

Ensure the program correctly handles the null

$-$

terminator character at the end of the string to maintain proper string formatting in memory.

Output:

After reversing, the program should ensure the modified string is correctly null

$-$

terminated and stored back at its original memory location.

$($

Hint:

$1$

$0$

$4$

$1$

$0$

$1$

$1$

$0$

$8$

$1$

$0$

$8$

$1$

$1$

$1$

$-$

this is the ascii code of hello

Convert it to hex

Then store in memory

$)$

This solution does not work in LEGv

$8$

Simulator. Please correct the code and try it in LEGv

$8$

Simulator. I need correct solution.

$.$

data

string:

$.$

byte

$0$

x

$4$

$8$

$,$

$0$

x

$6$

$5$

$,$

$0$

x

$6$

C

$,$

$0$

x

$6$

C

$,$

$0$

x

$6$

F

$,$

$0$

x

$2$

C

$,$

$0$

x

$2$

$0$

$,$

$0$

x

$5$

$7$

$,$

$0$

x

$6$

F

$,$

$0$

x

$7$

$2$

$,$

$0$

x

$6$

C

$,$

$0$

x

$6$

$4$

$,$

$0$

x

$2$

$1$

$,$

$0$

x

$2$

$1$

$,$

$0$

x

$2$

$1$

$,$

$0$

x

$0$

$0$

$.$

text

$.$

global

$\_$

start

$\_$

start:

$/$

$/$

Load the base address of the string

LDR X

$0$

$,$

$=$

string

$/$

$/$

Find the length of the string

MOV X

$1$

$,$

X

$0$

$/$

$/$

Copy base address to X

$1$

find

$\_$

end:

LDRB W

$2$

$,$

$[$

X

$1$

$]$

$/$

$/$

Load byte at X

$1$

into W

$2$

CBZ W

$2$

$,$

reverse

$/$

$/$

If byte is null, jump to reverse

ADD X

$1$

$,$

X

$1$

$,$

#

$1$

$/$

$/$

Increment X

$1$

B find

$\_$

end

reverse:

SUB X

$1$

$,$

X

$1$

$,$

#

$1$

$/$

$/$

Decrement X

$1$

to point to the last character

$/$

$/$

Set up pointers for swapping

MOV X

$2$

$,$

X

$0$

$/$

$/$

X

$2$

is the start pointer

MOV X

$3$

$,$

X

$1$

$/$

$/$

X

$3$

is the end pointer

swap:

CMP X

$2$

$,$

X

$3$

$/$

$/$

Compare start and end pointers

B

$.$

GT done

$/$

$/$

If start

$>$

end, we're done

is it safe to solve