117 lines
3.1 KiB
C++
117 lines
3.1 KiB
C++
#include <unistd.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <sys/soundcard.h>
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//OSSv4 features: define fallbacks for OSSv3 (where these ioctls are ignored)
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#ifndef SNDCTL_DSP_COOKEDMODE
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#define SNDCTL_DSP_COOKEDMODE _IOW('P', 30, int)
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#endif
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#ifndef SNDCTL_DSP_POLICY
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#define SNDCTL_DSP_POLICY _IOW('P', 45, int)
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#endif
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struct AudioOSS : Audio {
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~AudioOSS() { term(); }
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struct {
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int fd = -1;
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int format = AFMT_S16_LE;
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int channels = 2;
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} device;
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struct {
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string device = "/dev/dsp";
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bool synchronize = true;
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uint frequency = 48000;
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uint latency = 60;
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} settings;
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auto cap(const string& name) -> bool {
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if(name == Audio::Device) return true;
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if(name == Audio::Synchronize) return true;
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if(name == Audio::Frequency) return true;
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if(name == Audio::Latency) return true;
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return false;
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}
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auto get(const string& name) -> any {
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if(name == Audio::Device) return settings.device;
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if(name == Audio::Synchronize) return settings.synchronize;
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if(name == Audio::Frequency) return settings.frequency;
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if(name == Audio::Latency) return settings.latency;
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return {};
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}
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auto set(const string& name, const any& value) -> bool {
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if(name == Audio::Device && value.is<string>()) {
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settings.device = value.get<string>();
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if(!settings.device) settings.device = "/dev/dsp";
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return true;
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}
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if(name == Audio::Synchronize && value.is<bool>()) {
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settings.synchronize = value.get<bool>();
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updateSynchronization();
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return true;
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}
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if(name == Audio::Frequency && value.is<uint>()) {
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settings.frequency = value.get<uint>();
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if(device.fd >= 0) init();
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return true;
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}
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if(name == Audio::Latency && value.is<uint>()) {
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settings.latency = value.get<uint>();
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if(device.fd >= 0) init();
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return true;
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}
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return false;
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}
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auto sample(int16_t left, int16_t right) -> void {
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uint32_t sample = (uint16_t)left << 0 | (uint16_t)right << 16;
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auto unused = write(device.fd, &sample, 4);
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}
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auto clear() -> void {
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}
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auto init() -> bool {
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device.fd = open(settings.device, O_WRONLY, O_NONBLOCK);
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if(device.fd < 0) return false;
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int cooked = 1;
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ioctl(device.fd, SNDCTL_DSP_COOKEDMODE, &cooked);
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//policy: 0 = minimum latency (higher CPU usage); 10 = maximum latency (lower CPU usage)
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int policy = min(10, settings.latency / 20); //note: latency measurement isn't exact
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ioctl(device.fd, SNDCTL_DSP_POLICY, &policy);
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int frequency = settings.frequency;
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ioctl(device.fd, SNDCTL_DSP_CHANNELS, &device.channels);
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ioctl(device.fd, SNDCTL_DSP_SETFMT, &device.format);
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ioctl(device.fd, SNDCTL_DSP_SPEED, &frequency);
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updateSynchronization();
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return true;
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}
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auto term() -> void {
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if(device.fd >= 0) {
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close(device.fd);
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device.fd = -1;
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}
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}
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private:
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auto updateSynchronization() -> void {
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if(device.fd < 0) return;
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auto flags = fcntl(device.fd, F_GETFL);
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if(flags < 0) return;
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settings.synchronize ? flags &=~ O_NONBLOCK : flags |= O_NONBLOCK;
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fcntl(device.fd, F_SETFL, flags);
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}
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};
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