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//
// Copyright(C) 2005-2014 Simon Howard
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// DESCRIPTION:
// PC speaker driver for Linux.
//
#include "config.h"
#ifdef HAVE_LINUX_KD_H
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <linux/kd.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include "SDL.h"
#include "SDL_thread.h"
#include "pcsound.h"
#include "pcsound_internal.h"
#define CONSOLE_DEVICE "/dev/console"
static int console_handle;
static pcsound_callback_func callback;
static int sound_thread_running = 0;
static SDL_Thread *sound_thread_handle;
static int sleep_adjust = 0;
static void AdjustedSleep(unsigned int ms)
{
unsigned int start_time;
unsigned int end_time;
unsigned int actual_time;
// Adjust based on previous error to keep the tempo right
if (sleep_adjust > ms)
{
sleep_adjust -= ms;
return;
}
else
{
ms -= sleep_adjust;
}
// Do the sleep and record how long it takes
start_time = SDL_GetTicks();
SDL_Delay(ms);
end_time = SDL_GetTicks();
if (end_time > start_time)
{
actual_time = end_time - start_time;
}
else
{
actual_time = ms;
}
if (actual_time < ms)
{
actual_time = ms;
}
// Save sleep_adjust for next time
sleep_adjust = actual_time - ms;
}
static int SoundThread(void *unused)
{
int current_freq = 0;
int frequency;
int duration;
int cycles;
while (sound_thread_running)
{
callback(&duration, &frequency);
if (current_freq != frequency)
{
current_freq = frequency;
if (frequency != 0)
{
cycles = PCSOUND_8253_FREQUENCY / frequency;
}
else
{
cycles = 0;
}
ioctl(console_handle, KIOCSOUND, cycles);
}
AdjustedSleep(duration);
}
return 0;
}
static int PCSound_Linux_Init(pcsound_callback_func callback_func)
{
// Try to open the console
console_handle = open(CONSOLE_DEVICE, O_WRONLY);
if (console_handle == -1)
{
// Don't have permissions for the console device?
fprintf(stderr, "PCSound_Linux_Init: Failed to open '%s': %s\n",
CONSOLE_DEVICE, strerror(errno));
return 0;
}
if (ioctl(console_handle, KIOCSOUND, 0) < 0)
{
// KIOCSOUND not supported: non-PC linux?
close(console_handle);
return 0;
}
// Start a thread up to generate PC speaker output
callback = callback_func;
sound_thread_running = 1;
sound_thread_handle =
SDL_CreateThread(SoundThread, "PC speaker thread", NULL);
return 1;
}
static void PCSound_Linux_Shutdown(void)
{
sound_thread_running = 0;
SDL_WaitThread(sound_thread_handle, NULL);
close(console_handle);
}
pcsound_driver_t pcsound_linux_driver =
{
"Linux",
PCSound_Linux_Init,
PCSound_Linux_Shutdown,
};
#endif /* #ifdef HAVE_LINUX_KD_H */
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