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