/*
 * FTDI chip+driver combo (specifically the combination of FTDI chips and
 * ftdi_sio driver in Linux, not sure who is the actual culprit) exhibits
 * this unpleasant behaviour: even though we request "please flush all
 * previous input" when we set our termios params, old accumulated serial
 * Rx bytes still remain in some buffer somewhere, and a newly started
 * serial application receives this stale garbage.  As a workaround,
 * we do an additional flush of our own: we put the fd in non-blocking mode
 * and keep reading and discarding data until we get EAGAIN or EWOULDBLOCK.
 */

#include <sys/types.h>
#include <sys/errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

extern int target_fd;

void
init_serial_flush()
{
	u_char buf[512];
	int cc;

	set_serial_nonblock(1);
	for (;;) {
		cc = read(target_fd, buf, sizeof buf);
		if (cc <= 0)
			break;
	}
	if (cc == 0) {
		fprintf(stderr,
			"read EOF from serial port during initial flush\n");
		exit(1);
	}
	if (errno == EAGAIN || errno == EWOULDBLOCK)
		return;		/* success */
	perror("serial port read");
	exit(1);
}