linux/arch/x86/realmode/rm/wakemain.c

// SPDX-License-Identifier: GPL-2.0
#include "wakeup.h"
#include "boot.h"

static void udelay(int loops)
{ … }

static void beep(unsigned int hz)
{ … }

#define DOT_HZ …
#define DASH_HZ …
#define US_PER_DOT …

/* Okay, this is totally silly, but it's kind of fun. */
static void send_morse(const char *pattern)
{ … }

struct port_io_ops pio_ops;

void main(void)
{ … }