#include <stdio.h>

unsigned char rv(unsigned char n)
{
    return (n<<7)|(n>>7)|(n&0x7E);
}

int main()
{
    unsigned char s[] = "Hello, Dolly!";
    printf("%s\n",s);
    for(int i = 0; s[i]; i++) s[i] = rv(s[i]);
    printf("%s\n",s);
    for(int i = 0; s[i]; i++) s[i] = rv(s[i]);
    printf("%s\n",s);
}