Create An ARM Program To Check If String Is A Palindrome In Assembly Language Assignment Solution

Instructions

Write an Assembly language assignment program to shift string by n bits.

Requirements and Specifications

For this programming assignment, you will write an ARM program that does the following:

1. Prints "input a string".
2. Reads the input string.
3. Calculates the length of the string.
4. Outputs the string length to the console.
5. Determines if the string is a palindrome.
6. Outputs whether the string is a palindrome

Screenshots of output

Source Code

.section .data input_prompt : .asciz "Input a string: " input_spec : .asciz "%[^\n]" length_spec : .asciz "String length: %d\n" palindrome_spec : .asciz "String is a palindrome (T/F): %c\n" input: .space 10 // place to save string .section .text .global main # program execution begins here main: ldr x0, =input_prompt // load address of prompt string bl printf // print the prompt ldr x0, =input_spec // load address of spec to read a string ldr x1, =input // load address of place to save string bl scanf // read the string # calculate length ldr x0, =input // load input string address mov x19, 0 // start length in zero loop1: ldrb w1, [x0, x19] // load character from string cmp w1, 0 // if the character is end of string beq endloop1 // terminate loop add x19, x19, 1 // else increment string length b loop1 // repeat loop endloop1: # print length ldr x0, =length_spec // load address of string to print mov w1, w19 // copy length to w1 bl printf // print the length message # if length is <= 1, string is palindrome cmp x19, 1 ble palindrome # else, check if string is palindrome ldr x0, =input // load input string address mov w1, 'F' // by defaulf we assume string is not a palindrome mov x2, 0 // index from start of string (0) sub x3, x19, 1 // index from end of string (length - 1) loop2: ldrb w4, [x0, x2] // load character from start of string ldrb w5, [x0, x3] // load character from end of string cmp w4, w5 // if the characters are not equal bne printtf // print the result, not palindrome add x2, x2, 1 // advance start index to next char in string add x3, x3, -1 // move end index to previous char in string cmp x2, x3 // compare indices blt loop2 // continue in loop if indices don't cross // if indices cross, all other chars in front and back // were equal so it's a palindrome palindrome: mov w1, 'T' // is a palindrome printtf: # print palindrome result T or F ldr x0, =palindrome_spec // load address of string to print bl printf // print the palindrome message exit: mov x0, 0 mov x8, 93 svc 0 ret