lower upper binary op.

#include <stdio.h>

char lower(char c){
    return c | 0b0100000;
}

char upper(char c){
    return c & 0xdf;
}

int main()
{
    printf("%c,%c\n",'F', lower('F'));
    printf("%c,%c\n",'j', upper('j'));
    return 0;
}