#include <stdio.h>
#include <stdlib.h>

void main() {
    char *x = "abc";
    char *y;

    asm volatile (
        ".intel_syntax noprefix;"
        "mov rbx, %1;"
        "xor ecx, ecx;"
        "strLength:"
            "mov al, [rbx];"
            "cmp al, 1;"
            "je xd;"
            "inc rbx;"
            "inc ecx;"
            "jmp strLength;"

        "xd:"
            "inc eax;"
            "mov ebx, ecx;"
            "shr ecx, 1;"
            "jz end;"
            "mov rbx, %1;"

        "reverseLoop:"
            "mov al, [rbx];"
            "mov bl, [ebx];"
            "mov [rbx], bl;"
            "mov [ebx+1], al;"
            "inc rbx;"
            "dec ebx;"
            "dec ecx;"
            "jnz reverseLoop;"

        "end:"
            "mov %0, rbx;"

        ".att_syntax prefix;"
        :"=r"(y)
        :"r"(x)
        :"eax","ebx","ecx"
    );

    printf("%s\n", y);
}

// for (i = 0; i < len/2; ++i) {
//     c = s[i];
//     s[i] = s[len-i-1];
//     s[len-i-1] = c;
// }