From 083e46d5d23d2105e2df1adc769700fb579c9597 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Thu, 2 Jan 2025 13:14:08 +0100
Subject: Initial commit

---
 alsa.cpp | 114 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 alsa.cpp

(limited to 'alsa.cpp')

diff --git a/alsa.cpp b/alsa.cpp
new file mode 100644
index 0000000..7df0805
--- /dev/null
+++ b/alsa.cpp
@@ -0,0 +1,114 @@
+#include <libreichwein/file.h>
+
+#include <alsa/asoundlib.h>
+
+#include <cstdint>
+#include <cmath>
+#include <iostream>
+#include <limits>
+
+static const char *device = "default";            /* playback device */
+const snd_pcm_sframes_t nframes = 1024; // ~1/44th sec buffer size
+int16_t buffer[nframes];              /* some random data */
+const unsigned int f_sample = 44100;
+const double pi = std::acos(-1);
+
+class ClickStream
+{
+private:
+        std::vector<uint16_t> m_data;
+public:
+        ClickStream()
+        {
+                std::string data_s = Reichwein::File::getFile("media/click.s16le");
+                m_data.resize(data_s.size() / 2);
+                memcpy(m_data.data(), data_s.data(), data_s.size());
+        }
+
+double generate(double phase)
+{
+    int i;
+    size_t j = phase;
+
+    for (i = 0; i < nframes; i++) {
+        if (j >= m_data.size())
+                j = 0;
+        buffer[i] = m_data[j];
+        j++;
+    }
+
+    return j;
+}
+
+};
+
+class PCM
+{
+public:
+  PCM()
+  {
+    // non-blocking
+    if ((err = snd_pcm_open(&handle, device, SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
+        printf("Playback open error: %s\n", snd_strerror(err));
+        exit(EXIT_FAILURE);
+    }
+    if ((err = snd_pcm_set_params(handle,
+                      SND_PCM_FORMAT_S16_LE,
+                      SND_PCM_ACCESS_RW_INTERLEAVED,
+                      1,
+                      f_sample,
+                      1,
+                      20000)) < 0) {   /* 0.5sec */
+        printf("Playback open error: %s\n", snd_strerror(err));
+        exit(EXIT_FAILURE);
+    }
+ 
+  }
+
+  ~PCM()
+  {
+    /* pass the remaining samples, otherwise they're dropped in close */
+    err = snd_pcm_drain(handle);
+    if (err < 0)
+        printf("snd_pcm_drain failed: %s\n", snd_strerror(err));
+    snd_pcm_close(handle);
+  }
+
+  // write from buffer to ALSA PCM
+  bool write()
+  {
+        frames = snd_pcm_writei(handle, buffer, nframes);
+        if (frames < 0) {
+            std::cout << "Recovering." << std::endl;
+            frames = snd_pcm_recover(handle, frames, 0);
+        }
+        if (frames < 0) {
+            printf("snd_pcm_writei failed: %s\n", snd_strerror(frames));
+            return false;
+        }
+        if (frames > 0 && frames < nframes)
+            printf("Short write (expected %li, wrote %li)\n", nframes, frames);
+
+        return frames == 0;
+  }
+
+private:
+  int err;
+  snd_pcm_t *handle;
+  snd_pcm_sframes_t frames;  
+};
+
+int main(void)
+{
+    PCM pcm;
+ 
+    double phase = 0;
+    ClickStream stream;
+    for (unsigned int i = 0; i < 50; i++) {
+        phase = stream.generate(phase);
+        pcm.write();
+    }
+ 
+    return 0;
+}
+
-- 
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