frodo-wii/Src/SID_linux.h
2010-02-09 11:41:30 +00:00

144 lines
3.3 KiB
C

/*
* SID_linux.h - 6581 emulation, Linux specific stuff
*
* Frodo (C) 1994-1997,2002-2005 Christian Bauer
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/soundcard.h>
#include "utils.hh"
#include "VIC.h"
#include "Network.h"
/*
* Initialization
*/
void DigitalRenderer::init_sound(void)
{
int arg;
unsigned long format;
ready = false;
devfd = open("/dev/dsp", O_WRONLY);
if (devfd < 0)
return;
ioctl(devfd, SNDCTL_DSP_GETFMTS, &format);
if (!(format & AFMT_S16_LE))
return;
format = AFMT_S16_LE;
ioctl(devfd, SNDCTL_DSP_SETFMT, &format);
// Buffer size: 2^9 == 512 bytes. Note that too large buffers will not work
// very well: The speed of the C64 is slowed down to an average speed of
// 100% by the blocking write() call in EmulateLine(). If you use a buffer
// of, say 4096 bytes, that will happen only about every 4 frames, which
// means that the emulation runs much faster in some frames, and much
// slower in others.
// On really fast machines, it might make sense to use an even smaller
// buffer size.
arg = 0x00100009;
ioctl(devfd, SNDCTL_DSP_SETFRAGMENT, &arg);
arg = 0;
ioctl(devfd, SNDCTL_DSP_STEREO, &arg);
arg = 32000;
ioctl(devfd, SNDCTL_DSP_SPEED, &arg);
ioctl(devfd, SOUND_PCM_READ_RATE, &arg);
if (arg < 30000 || arg > 45000)
return;
sndbufsize = 0;
ioctl(devfd, SNDCTL_DSP_GETBLKSIZE, &sndbufsize);
sound_buffer = new int16[sndbufsize];
ready = true;
}
/*
* Destructor
*/
DigitalRenderer::~DigitalRenderer()
{
if (devfd >= 0)
close(devfd);
}
/*
* Pause sound output
*/
void DigitalRenderer::Pause(void)
{
}
/*
* Resume sound output
*/
void DigitalRenderer::Resume(void)
{
}
/*
* Fill buffer, sample volume (for sampled voice)
*/
void DigitalRenderer::PushVolume(uint8 vol)
{
static int divisor = 0;
static int to_output = 0;
static int buffer_pos = 0;
sample_buf[sample_in_ptr] = vol;
sample_in_ptr = (sample_in_ptr + 1) % SAMPLE_BUF_SIZE;
// Now see how many samples have to be added for this line
divisor += SAMPLE_FREQ;
while (divisor >= 0)
divisor -= TOTAL_RASTERS*SCREEN_FREQ, to_output++;
// Calculate the sound data only when we have enough to fill
// the buffer entirely
if ((buffer_pos + to_output) >= sndbufsize) {
int datalen = sndbufsize - buffer_pos;
ssize_t written;
to_output -= datalen;
calc_buffer(sound_buffer + buffer_pos, datalen*2);
written = write(devfd, sound_buffer, sndbufsize*2);
if (written < 0)
warning("Failed to write sound\n");
buffer_pos = 0;
}
}
void DigitalRenderer::EmulateLine(void)
{
if (!ready)
return;
this->PushVolume(volume);
}