/*
keytest.c
Outputs hexadecimal keycode(s) for each key pressed at the terminal
Press ESC to exit the program.

Written by Taylor Gurney, 2022.
Public domain.
*/
#include <stdlib.h>
#include <stdio.h>
#include <termios.h>
#include <unistd.h>

int main(void) {
    struct termios t;
    char c[8] = {0};
    ssize_t inlen = 0;
    int i;

    if (!isatty(0)) {
        puts("error: stdin is not a tty\n");
        exit(1);
    }
    if (tcgetattr(0, &t) < 0) {
        puts("tcgetattr failed");
        exit(1);
    }
    t.c_lflag &= ~ICANON;
    t.c_lflag &= ~ECHO;
    t.c_lflag &= ~ISIG;
    t.c_iflag &= ~IXOFF;
    t.c_iflag &= ~IXON;
    t.c_iflag &= ~ICRNL;

    if (tcsetattr(TCSADRAIN, 0, &t) < 0) {
        puts("tcsetattr failed");
        exit(1);
    }
    
    puts("Press ESC to exit");

    while ((inlen = read(0, c, 8)) > 0) {
        if (inlen == 1 && *c == '\033') {
            puts("");
            exit(0);
        }
        for (i = 0; i < inlen; i++) {
            printf("%02hhx ", c[i]);
            fflush(stdout);
        }
        if (inlen == 1) {
            printf("\n%c\n", *c);
            fflush(stdout);
        }
    }
}