| 1 |
/* |
| 2 |
* SID_linux.h - 6581 emulation, Linux specific stuff |
| 3 |
* |
| 4 |
* Frodo Copyright (C) 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 |
|
| 27 |
/* |
| 28 |
* Initialization |
| 29 |
*/ |
| 30 |
|
| 31 |
void DigitalRenderer::init_sound(void) |
| 32 |
{ |
| 33 |
int arg; |
| 34 |
unsigned long format; |
| 35 |
|
| 36 |
ready = false; |
| 37 |
devfd = open("/dev/dsp", O_WRONLY); |
| 38 |
if (devfd < 0) |
| 39 |
return; |
| 40 |
|
| 41 |
ioctl(devfd, SNDCTL_DSP_GETFMTS, &format); |
| 42 |
if (!(format & AFMT_S16_LE)) |
| 43 |
return; |
| 44 |
format = AFMT_S16_LE; |
| 45 |
ioctl(devfd, SNDCTL_DSP_SETFMT, &format); |
| 46 |
|
| 47 |
// Buffer size: 2^9 == 512 bytes. Note that too large buffers will not work |
| 48 |
// very well: The speed of the C64 is slowed down to an average speed of |
| 49 |
// 100% by the blocking write() call in EmulateLine(). If you use a buffer |
| 50 |
// of, say 4096 bytes, that will happen only about every 4 frames, which |
| 51 |
// means that the emulation runs much faster in some frames, and much |
| 52 |
// slower in others. |
| 53 |
// On really fast machines, it might make sense to use an even smaller |
| 54 |
// buffer size. |
| 55 |
arg = 0x00100009; |
| 56 |
ioctl(devfd, SNDCTL_DSP_SETFRAGMENT, &arg); |
| 57 |
arg = 0; |
| 58 |
ioctl(devfd, SNDCTL_DSP_STEREO, &arg); |
| 59 |
arg = 44100; |
| 60 |
ioctl(devfd, SNDCTL_DSP_SPEED, &arg); |
| 61 |
ioctl(devfd, SOUND_PCM_READ_RATE, &arg); |
| 62 |
if (arg < 43000 || arg > 45000) |
| 63 |
return; |
| 64 |
|
| 65 |
ioctl(devfd, SNDCTL_DSP_GETBLKSIZE, &sndbufsize); |
| 66 |
sound_buffer = new int16[sndbufsize]; |
| 67 |
ready = true; |
| 68 |
} |
| 69 |
|
| 70 |
|
| 71 |
/* |
| 72 |
* Destructor |
| 73 |
*/ |
| 74 |
|
| 75 |
DigitalRenderer::~DigitalRenderer() |
| 76 |
{ |
| 77 |
if (devfd >= 0) |
| 78 |
close(devfd); |
| 79 |
} |
| 80 |
|
| 81 |
|
| 82 |
/* |
| 83 |
* Pause sound output |
| 84 |
*/ |
| 85 |
|
| 86 |
void DigitalRenderer::Pause(void) |
| 87 |
{ |
| 88 |
} |
| 89 |
|
| 90 |
|
| 91 |
/* |
| 92 |
* Resume sound output |
| 93 |
*/ |
| 94 |
|
| 95 |
void DigitalRenderer::Resume(void) |
| 96 |
{ |
| 97 |
} |
| 98 |
|
| 99 |
|
| 100 |
/* |
| 101 |
* Fill buffer, sample volume (for sampled voice) |
| 102 |
*/ |
| 103 |
|
| 104 |
void DigitalRenderer::EmulateLine(void) |
| 105 |
{ |
| 106 |
static int divisor = 0; |
| 107 |
static int to_output = 0; |
| 108 |
static int buffer_pos = 0; |
| 109 |
|
| 110 |
if (!ready) |
| 111 |
return; |
| 112 |
|
| 113 |
sample_buf[sample_in_ptr] = volume; |
| 114 |
sample_in_ptr = (sample_in_ptr + 1) % SAMPLE_BUF_SIZE; |
| 115 |
|
| 116 |
// Now see how many samples have to be added for this line |
| 117 |
divisor += SAMPLE_FREQ; |
| 118 |
while (divisor >= 0) |
| 119 |
divisor -= TOTAL_RASTERS*SCREEN_FREQ, to_output++; |
| 120 |
|
| 121 |
// Calculate the sound data only when we have enough to fill |
| 122 |
// the buffer entirely |
| 123 |
if ((buffer_pos + to_output) >= sndbufsize) { |
| 124 |
int datalen = sndbufsize - buffer_pos; |
| 125 |
to_output -= datalen; |
| 126 |
calc_buffer(sound_buffer + buffer_pos, datalen*2); |
| 127 |
write(devfd, sound_buffer, sndbufsize*2); |
| 128 |
buffer_pos = 0; |
| 129 |
} |
| 130 |
} |
