keycode_scanner_mac.c

#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <termios.h>
#include <stdio.h>
#include <fcntl.h>

// Read more
// https://forums.raspberrypi.com/viewtopic.php?t=142867
// https://www.kernel.org/doc/Documentation/input/input-programming.txt
// https://stackoverflow.com/questions/6731317/c-exit-from-infinite-loop-on-keypress/6731427#6731427
// https://web.archive.org/web/20180401093525/http://cc.byexamples.com/2007/04/08/non-blocking-user-input-in-loop-without-ncurses/
// https://man7.org/linux/man-pages/man2/select.2.html
// https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/fcntl.2.html


// Refer: https://cboard.cprogramming.com/c-programming/178177-very-simple-program-impossible-create-mac-post1290358.html#post1290358
int kbhit(void)
{
    struct termios oldt, newt;
    int ch;
    int oldf;
    
    tcgetattr(STDIN_FILENO, &oldt);
    newt = oldt;
    newt.c_lflag &= ~(ICANON | ECHO);
    tcsetattr(STDIN_FILENO, TCSANOW, &newt);
    oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
    fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);
    
    ch = getchar();
    
    tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
    fcntl(STDIN_FILENO, F_SETFL, oldf);
    
    if(ch != EOF)
    {
        ungetc(ch, stdin);
        return 1;
    }
    
    return 0;
}

// Refer: https://stackoverflow.com/a/23035044
static int getch(void)
{
    struct termios oldattr, newattr;
    int ch;
    tcgetattr( STDIN_FILENO, &oldattr );
    newattr = oldattr;
    newattr.c_lflag &= ~( ICANON | ECHO );
    tcsetattr( STDIN_FILENO, TCSANOW, &newattr );
    ch = getchar();
    tcsetattr( STDIN_FILENO, TCSANOW, &oldattr );
    return ch;
}

int main(int argc, char *argv[])
{
    while(1)
    {
        do
        {
            int c = getch();
            printf("C: %02x\n", c);
        } while(kbhit());
        
        printf("------\n");
    }
    return 0;
}