1 files changed, 149 insertions, 0 deletions
diff --git a/PCM.cpp b/PCM.cpp
index b70652c..e6d915f 100644
--- a/PCM.cpp
+++ b/PCM.cpp
@@ -1 +1,150 @@
 #include "PCM.h"
+
+PCM::PCM(): m_phase(1000000)
+{
+  // prepare the sample
+  std::string data_s = Reichwein::File::getFile("media/click.s16le");
+  m_data.resize(data_s.size() / 2); // src is in bytes
+  memcpy(m_data.data(), data_s.data(), data_s.size());
+
+  // non-blocking
+  if ((err = snd_pcm_open(&handle, device, SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK)) < 0) {
+    throw std::runtime_error(fmt::format("Playback open error: {}", snd_strerror(err)));
+  }
+  if ((err = snd_pcm_set_params(handle,
+                                SND_PCM_FORMAT_S16_LE,
+                                SND_PCM_ACCESS_RW_INTERLEAVED,
+                                1,
+                                f_sample,
+                                1,
+                                pcm_latency_us)) < 0) {   // latency in us
+    throw std::runtime_error(fmt::format("Playback open error: {}", snd_strerror(err)));
+  }
+
+  generate();
+
+  npfd = snd_pcm_poll_descriptors_count(handle);
+  if (npfd < 0) {
+    throw std::runtime_error("snd_pcm_poll_descriptors_count() failed");
+  }
+  pfd = (struct pollfd *)malloc(npfd * sizeof(struct pollfd));
+  if (pfd == nullptr) {
+    throw std::runtime_error("alloca() error for PCM");
+  }
+  if (0 > snd_pcm_poll_descriptors(handle, pfd, npfd))
+  {
+    throw std::runtime_error("snd_pcm_poll_descriptors() failure");
+  }
+
+  if (0 > snd_pcm_start(handle))
+  {
+   throw std::runtime_error("PCM could not be started");
+  }
+
+  if (npfd != 1) {
+    std::cout << "Warning: " << std::to_string(npfd) << " poll fds for pcm" << std::endl;
+  } else if (fd() <= 2) {
+    std::cout << "Warning: Bad PCM fd: " << std::to_string(fd()) << std::endl;
+  }
+}
+
+PCM::~PCM()
+{
+  // pass the remaining samples, otherwise they're dropped in close
+  err = snd_pcm_drain(handle);
+  if (err < 0)
+      std::cerr << fmt::format("snd_pcm_drain failed: {}", snd_strerror(err)) << std::endl;
+  snd_pcm_close(handle);
+
+  free(pfd);
+}
+
+void PCM::click()
+{
+  snd_pcm_sframes_t delay;
+  if (0 > snd_pcm_delay(handle, &delay)) {
+  }
+
+  m_phase = - click_latency_frames + delay;
+}
+
+// generate 1 buffer size
+void PCM::generate()
+{
+  int i;
+
+  for (i = 0; i < nframes; i++) {
+    if (m_phase < 0 || m_phase >= m_data.size())
+    {
+      buffer[i] = 0;
+    }
+    else
+    {
+      buffer[i] = m_data[m_phase];
+    }
+    m_phase++;
+  }
+}
+
+int PCM::fd()
+{
+  return pfd->fd;
+}
+
+// write from buffer to ALSA PCM
+void PCM::write()
+{
+  snd_pcm_sframes_t written = snd_pcm_writei(handle, buffer, nframes);
+  if (written < 0) {
+      if (written == -EPIPE) {
+        std::cout << "Warning: PCM underrun" << std::endl;
+      }
+      std::cout << "Recovering." << std::endl;
+      written = snd_pcm_recover(handle, written, 0);
+  }
+  if (written < 0) {
+      throw std::runtime_error("snd_pcm_writei failed: "s + snd_strerror(written));
+  }
+
+  if (written != nframes) {
+    std::cout << "Warning: written " << std::to_string(written) << " frames instead of "<< std::to_string(nframes) << std::endl;
+  }
+
+  snd_pcm_sframes_t avail;
+  snd_pcm_sframes_t delay;
+  if (0 > snd_pcm_avail_delay(handle, &avail, &delay)) {
+    log_cout << "Error detecting avail and delay" << std::endl;
+  } else {
+    debug_cout << fmt::format("Delay: {}, avail. buffer; {} frames", delay, avail) << std::endl;
+  }
+
+  generate();
+}
+
+bool PCM::wait_for_event()
+{
+  int result = poll(pfd, npfd, 10000);
+  if (result > 0)
+  {
+    // event
+    return true;
+  }
+  else if (result == 0) {
+    // timeout
+    return false;
+  } else {
+    throw std::runtime_error("Poll unsuccessful");
+  }
+}
+
+bool PCM::write_available()
+{
+  snd_pcm_sframes_t result = snd_pcm_avail(handle);
+  if (0 > result) {
+    std::cerr << "Error: snd_pcm_avail()" << std::endl;
+    //throw std::runtime_error("snd_pcm_avail()");
+  }
+
+  return result >= nframes;
+}
+