getch.c revision 58432eb9cea995c69b4f905e68b38c1b8216edeb 
1/*
2C non-blocking keyboard input
3http://stackoverflow.com/questions/448944/c-non-blocking-keyboard-input
4*/
5
6#include <stdlib.h>
7#include <string.h>
8#include <sys/select.h>
9#include <termios.h>
10#include <unistd.h>
11#include "getch.h"
12
13struct termios orig_termios;
14
15void reset_terminal_mode()
16{
17    tcsetattr(0, TCSANOW, &orig_termios);
18}
19
20void set_conio_terminal_mode()
21{
22    struct termios new_termios;
23
24    /* take two copies - one for now, one for later */
25    tcgetattr(0, &orig_termios);
26    memcpy(&new_termios, &orig_termios, sizeof(new_termios));
27
28    /* register cleanup handler, and set the new terminal mode */
29    atexit(reset_terminal_mode);
30    cfmakeraw(&new_termios);
31    new_termios.c_oflag |= OPOST;
32    tcsetattr(0, TCSANOW, &new_termios);
33}
34
35int kbhit()
36{
37    struct timeval tv = { 0L, 0L };
38    fd_set fds;
39    FD_ZERO(&fds); // not in original posting to stackoverflow
40    FD_SET(0, &fds);
41    return select(1, &fds, NULL, NULL, &tv);
42}
43
44int getch()
45{
46    int r;
47    unsigned char c;
48    if ((r = read(0, &c, sizeof(c))) < 0) {
49        return r;
50    } else {
51        return c;
52    }
53}
54
55#if 0
56int main(int argc, char *argv[])
57{
58    set_conio_terminal_mode();
59
60    while (!kbhit()) {
61        /* do some work */
62    }
63    (void)getch(); /* consume the character */
64}
65#endif
66