Frodo4/Src/SID_linux.h

/*
 *  SID_linux.h - 6581 emulation, Linux specific stuff
 *
 *  Frodo (C) 1994-1997,2002 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 "VIC.h"


/*
 *  Initialization
 */

void DigitalRenderer::init_sound(void)
{
    int tmp;
    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.
     */
    tmp = 0x00100009;
    ioctl(devfd, SNDCTL_DSP_SETFRAGMENT, &tmp);
    tmp = 0;
    ioctl(devfd, SNDCTL_DSP_STEREO, &tmp);
    tmp = 44100;
    ioctl(devfd, SNDCTL_DSP_SPEED, &tmp);
    ioctl(devfd, SOUND_PCM_READ_RATE, &tmp);
    if (tmp < 43000 || tmp > 45000)
        return;

    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::EmulateLine(void)
{
    static int divisor = 0;
    static int to_output = 0;
    static int buffer_pos = 0;

    if (!ready)
        return;

        sample_buf[sample_in_ptr] = volume;
        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;
        to_output -= datalen;
        calc_buffer(sound_buffer + buffer_pos, datalen*2);
        write(devfd, sound_buffer, sndbufsize*2);
        buffer_pos = 0;
    }    
}
Revision:	1.1
Committed:	2003-07-01T17:36:32Z (21 years, 4 months ago) by cebix
Content type:	text/plain
Branch:	MAIN
Log Message:	imported files
#	User	Rev	Content
1	cebix	1.1	/*
2			* SID_linux.h - 6581 emulation, Linux specific stuff
3			*
4			* Frodo (C) 1994-1997,2002 Christian Bauer
5			*
6			* This program is free software; you can redistribute it and/or modify
7			* it under the terms of the GNU General Public License as published by
8			* the Free Software Foundation; either version 2 of the License, or
9			* (at your option) any later version.
10			*
11			* This program is distributed in the hope that it will be useful,
12			* but WITHOUT ANY WARRANTY; without even the implied warranty of
13			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14			* GNU General Public License for more details.
15			*
16			* You should have received a copy of the GNU General Public License
17			* along with this program; if not, write to the Free Software
18			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19			*/
20
21			#include <unistd.h>
22			#include <fcntl.h>
23			#include <sys/ioctl.h>
24			#include <linux/soundcard.h>
25
26			#include "VIC.h"
27
28
29			/*
30			* Initialization
31			*/
32
33			void DigitalRenderer::init_sound(void)
34			{
35			int tmp;
36			unsigned long format;
37
38			ready = false;
39			devfd = open("/dev/dsp", O_WRONLY);
40			if (devfd < 0)
41			return;
42
43			ioctl(devfd, SNDCTL_DSP_GETFMTS, &format);
44			if (!(format & AFMT_S16_LE))
45			return;
46			format = AFMT_S16_LE;
47			ioctl(devfd, SNDCTL_DSP_SETFMT, &format);
48
49			/*
50			* Buffer size: 2^9 == 512 bytes. Note that too large buffers will not work
51			* very well: The speed of the C64 is slowed down to an average speed of
52			* 100% by the blocking write() call in EmulateLine(). If you use a buffer
53			* of, say 4096 bytes, that will happen only about every 4 frames, which
54			* means that the emulation runs much faster in some frames, and much
55			* slower in others.
56			* On really fast machines, it might make sense to use an even smaller
57			* buffer size.
58			*/
59			tmp = 0x00100009;
60			ioctl(devfd, SNDCTL_DSP_SETFRAGMENT, &tmp);
61			tmp = 0;
62			ioctl(devfd, SNDCTL_DSP_STEREO, &tmp);
63			tmp = 44100;
64			ioctl(devfd, SNDCTL_DSP_SPEED, &tmp);
65			ioctl(devfd, SOUND_PCM_READ_RATE, &tmp);
66			if (tmp < 43000 \|\| tmp > 45000)
67			return;
68
69			ioctl(devfd, SNDCTL_DSP_GETBLKSIZE, &sndbufsize);
70			sound_buffer = new int16[sndbufsize];
71			ready = true;
72			}
73
74
75			/*
76			* Destructor
77			*/
78
79			DigitalRenderer::~DigitalRenderer()
80			{
81			if (devfd >= 0)
82			close(devfd);
83			}
84
85
86			/*
87			* Pause sound output
88			*/
89
90			void DigitalRenderer::Pause(void)
91			{
92			}
93
94
95			/*
96			* Resume sound output
97			*/
98
99			void DigitalRenderer::Resume(void)
100			{
101			}
102
103
104			/*
105			* Fill buffer, sample volume (for sampled voice)
106			*/
107
108			void DigitalRenderer::EmulateLine(void)
109			{
110			static int divisor = 0;
111			static int to_output = 0;
112			static int buffer_pos = 0;
113
114			if (!ready)
115			return;
116
117			sample_buf[sample_in_ptr] = volume;
118			sample_in_ptr = (sample_in_ptr + 1) % SAMPLE_BUF_SIZE;
119
120			/*
121			* Now see how many samples have to be added for this line
122			*/
123			divisor += SAMPLE_FREQ;
124			while (divisor >= 0)
125			divisor -= TOTAL_RASTERS*SCREEN_FREQ, to_output++;
126
127			/*
128			* Calculate the sound data only when we have enough to fill
129			* the buffer entirely.
130			*/
131			if ((buffer_pos + to_output) >= sndbufsize) {
132			int datalen = sndbufsize - buffer_pos;
133			to_output -= datalen;
134			calc_buffer(sound_buffer + buffer_pos, datalen*2);
135			write(devfd, sound_buffer, sndbufsize*2);
136			buffer_pos = 0;
137			}
138			}