xref: /aosp_15_r20/frameworks/wilhelm/tests/sandbox/getch.c (revision bebae9c0e76121f8312ccb50385c080b3a0b023c)

/*
C non-blocking keyboard input
http://stackoverflow.com/questions/448944/c-non-blocking-keyboard-input
*/

#include <stdlib.h>
#include <string.h>
#include <sys/select.h>
#include <termios.h>
#include <unistd.h>
#include "getch.h"

struct termios orig_termios;

void reset_terminal_mode()
{
    tcsetattr(0, TCSANOW, &orig_termios);
}

void set_conio_terminal_mode()
{
    struct termios new_termios;

    /* take two copies - one for now, one for later */
    tcgetattr(0, &orig_termios);
    memcpy(&new_termios, &orig_termios, sizeof(new_termios));

    /* register cleanup handler, and set the new terminal mode */
    atexit(reset_terminal_mode);
    cfmakeraw(&new_termios);
    new_termios.c_oflag |= OPOST;
    tcsetattr(0, TCSANOW, &new_termios);
}

int kbhit()
{
    struct timeval tv = { 0L, 0L };
    fd_set fds;
    FD_ZERO(&fds); // not in original posting to stackoverflow
    FD_SET(0, &fds);
    return select(1, &fds, NULL, NULL, &tv);
}

int getch()
{
    int r;
    unsigned char c;
    if ((r = read(0, &c, sizeof(c))) < 0) {
        return r;
    } else {
        return c;
    }
}

#if 0
int main(int argc, char *argv[])
{
    set_conio_terminal_mode();

    while (!kbhit()) {
        /* do some work */
    }
    (void)getch(); /* consume the character */
}
#endif