/*
    stackframe.c
    Jeff Ondich, 1 May 2026

    This silly program is intended to help us take a look
    at stack frames. In particular, we're interested in where
    the buffer in is_palindrome gets stored, what happens on
    call and ret instructions, etc.

    Compile like this:

        gcc -Wall -Werror -g -Og -o stackframe stackframe.c
*/

#include <stdio.h>
#include <string.h>
#include <stdbool.h>

#define BUFFER_SIZE 100

void reverse(const char *s, char *t) {
    if (s == NULL || t == NULL) {
        return;
    }

    int length = strlen(s);
    for (int k = 0; k < length; k++) {
        t[k] = s[length - k - 1];
    }
    t[length] = '\0';
}

bool is_palindrome(const char *s) {
    int length = strlen(s);
    if (length >= BUFFER_SIZE) {
        return false;
    }

    char reversed[BUFFER_SIZE];
    reverse(s, reversed);
    return strcmp(s, reversed) == 0;
}

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s string\n", argv[0]);
        printf("    where string is to be tested as a palindrome\n");
        return 1;
    }

    if (is_palindrome(argv[1])) {
        printf("Yes, it's a palindrome\n");
    } else {
        printf("No, it is not a palindrome\n");
    }

    return 0;
}