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/* |
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* SID_linux.h - 6581 emulation, Linux specific stuff |
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* |
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* Frodo (C) 1994-1997,2002 Christian Bauer |
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* Frodo Copyright (C) Christian Bauer |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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#include <sys/ioctl.h> |
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#include <linux/soundcard.h> |
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– |
#include "VIC.h" |
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/* |
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* Initialization |
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void DigitalRenderer::init_sound(void) |
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{ |
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int tmp; |
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unsigned long format; |
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int arg; |
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unsigned long format; |
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ready = false; |
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devfd = open("/dev/dsp", O_WRONLY); |
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if (devfd < 0) |
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return; |
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ioctl(devfd, SNDCTL_DSP_GETFMTS, &format); |
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if (!(format & AFMT_S16_LE)) |
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return; |
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format = AFMT_S16_LE; |
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ioctl(devfd, SNDCTL_DSP_SETFMT, &format); |
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/* |
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* Buffer size: 2^9 == 512 bytes. Note that too large buffers will not work |
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* very well: The speed of the C64 is slowed down to an average speed of |
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* 100% by the blocking write() call in EmulateLine(). If you use a buffer |
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* of, say 4096 bytes, that will happen only about every 4 frames, which |
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* means that the emulation runs much faster in some frames, and much |
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* slower in others. |
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* On really fast machines, it might make sense to use an even smaller |
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* buffer size. |
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*/ |
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tmp = 0x00100009; |
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ioctl(devfd, SNDCTL_DSP_SETFRAGMENT, &tmp); |
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tmp = 0; |
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ioctl(devfd, SNDCTL_DSP_STEREO, &tmp); |
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tmp = 44100; |
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ioctl(devfd, SNDCTL_DSP_SPEED, &tmp); |
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ioctl(devfd, SOUND_PCM_READ_RATE, &tmp); |
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if (tmp < 43000 || tmp > 45000) |
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return; |
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ioctl(devfd, SNDCTL_DSP_GETBLKSIZE, &sndbufsize); |
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sound_buffer = new int16[sndbufsize]; |
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ready = true; |
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ready = false; |
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devfd = open("/dev/dsp", O_WRONLY); |
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if (devfd < 0) |
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return; |
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ioctl(devfd, SNDCTL_DSP_GETFMTS, &format); |
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if (!(format & AFMT_S16_LE)) |
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return; |
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format = AFMT_S16_LE; |
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ioctl(devfd, SNDCTL_DSP_SETFMT, &format); |
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|
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// Buffer size: 2^9 == 512 bytes. Note that too large buffers will not work |
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// very well: The speed of the C64 is slowed down to an average speed of |
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// 100% by the blocking write() call in EmulateLine(). If you use a buffer |
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// of, say 4096 bytes, that will happen only about every 4 frames, which |
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// means that the emulation runs much faster in some frames, and much |
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// slower in others. |
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// On really fast machines, it might make sense to use an even smaller |
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// buffer size. |
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arg = 0x00100009; |
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ioctl(devfd, SNDCTL_DSP_SETFRAGMENT, &arg); |
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arg = 0; |
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ioctl(devfd, SNDCTL_DSP_STEREO, &arg); |
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arg = 44100; |
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ioctl(devfd, SNDCTL_DSP_SPEED, &arg); |
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ioctl(devfd, SOUND_PCM_READ_RATE, &arg); |
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if (arg < 43000 || arg > 45000) |
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return; |
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ioctl(devfd, SNDCTL_DSP_GETBLKSIZE, &sndbufsize); |
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sound_buffer = new int16[sndbufsize]; |
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ready = true; |
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} |
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DigitalRenderer::~DigitalRenderer() |
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{ |
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if (devfd >= 0) |
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close(devfd); |
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if (devfd >= 0) |
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close(devfd); |
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} |
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void DigitalRenderer::EmulateLine(void) |
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{ |
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static int divisor = 0; |
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static int to_output = 0; |
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static int buffer_pos = 0; |
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static int divisor = 0; |
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static int to_output = 0; |
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static int buffer_pos = 0; |
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if (!ready) |
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return; |
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if (!ready) |
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return; |
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sample_buf[sample_in_ptr] = volume; |
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sample_in_ptr = (sample_in_ptr + 1) % SAMPLE_BUF_SIZE; |
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/* |
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* Now see how many samples have to be added for this line |
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*/ |
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divisor += SAMPLE_FREQ; |
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while (divisor >= 0) |
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divisor -= TOTAL_RASTERS*SCREEN_FREQ, to_output++; |
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/* |
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* Calculate the sound data only when we have enough to fill |
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* the buffer entirely. |
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*/ |
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if ((buffer_pos + to_output) >= sndbufsize) { |
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int datalen = sndbufsize - buffer_pos; |
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to_output -= datalen; |
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calc_buffer(sound_buffer + buffer_pos, datalen*2); |
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write(devfd, sound_buffer, sndbufsize*2); |
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buffer_pos = 0; |
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} |
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// Now see how many samples have to be added for this line |
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divisor += SAMPLE_FREQ; |
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while (divisor >= 0) |
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divisor -= TOTAL_RASTERS*SCREEN_FREQ, to_output++; |
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// Calculate the sound data only when we have enough to fill |
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// the buffer entirely |
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if ((buffer_pos + to_output) >= sndbufsize) { |
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int datalen = sndbufsize - buffer_pos; |
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to_output -= datalen; |
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calc_buffer(sound_buffer + buffer_pos, datalen*2); |
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write(devfd, sound_buffer, sndbufsize*2); |
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buffer_pos = 0; |
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} |
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} |
