Turn off canonical mode , forward stdin to stdout, and write \n per 100ms

period.c

// Linux: gcc -Wall -o period period.c -lpthread
// Mingw: gcc -Wall -o period.exe period.c 

#include <stdio.h>

#define PERIOD 100	// 100 ms

#if defined(_MSC_VER) || defined(__MINGW32__) || defined(__MINGW64__)

#include <windows.h>

static void
set_non_canonical()
{
    DWORD mode;
    HANDLE console = GetStdHandle(STD_INPUT_HANDLE);

    GetConsoleMode(console, &mode);
    SetConsoleMode(console, mode & ~ENABLE_LINE_INPUT);
}

static DWORD WINAPI
timer(LPVOID lpParam) {
	for (;;) {
		Sleep(PERIOD);
		printf("\n");
		fflush(stdout);
	}
	return 0;
}

static void
start_timer() {
	CreateThread(NULL, 0, timer, NULL, 0, NULL);
}

#else

#include <termios.h>

static void
set_non_canonical()
{
   struct termios mode;

    tcgetattr(0, &mode);
	mode.c_cc[VMIN] = 1;
	mode.c_cc[VTIME] = 0;
	tcsetattr (STDIN_FILENO, TCSAFLUSH, &mode);
}

#include <pthread.h>
#include <unistd.h>

static void *
timer(void *dummy) {
	for (;;) {
		usleep(1000 * PERIOD);
	}
	return NULL;
}

static void
start_timer() {
	pthread_t pid;
	pthread_create(&pid, NULL, timer, NULL);
}


#endif

int
main() {
	start_timer();
	set_non_canonical();
	setvbuf(stdin, NULL, _IONBF, 0);
	int c;
	while((c = getchar()) != EOF)
	{
		if (c == '\n' || c == '\r') {
			if (c == '\n')
				putchar(255);
		} else {
			putchar(c);
			fflush(stdout);
		}
	}
	return 0;
}