add first code bits of new alsa encoder

1 files changed, 123 insertions, 0 deletions

diff --git a/src/SampleQueue.h b/src/SampleQueue.h
new file mode 100644
index 0000000..fddc3a4
--- /dev/null
+++ b/src/SampleQueue.h
@@ -0,0 +1,123 @@
+/*
+   Copyright (C) 2013, 2014
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+   An implementation for a threadsafe queue using boost thread library
+   for audio samples.
+*/
+
+#ifndef _SAMPLE_QUEUE_H_
+#define _SAMPLE_QUEUE_H_
+
+#include <boost/thread.hpp>
+#include <queue>
+
+/* This queue is meant to be used by two threads. One producer
+ * that pushes elements into the queue, and one consumer that
+ * retrieves the elements.
+ *
+ * The queue can make the consumer block until enough elements
+ * are available.
+ */
+
+template<typename T>
+class SampleQueue
+{
+public:
+    SampleQueue(unsigned int bytes_per_sample,
+            unsigned int channels,
+            size_t max_size) :
+        m_bytes_per_sample(bytes_per_sample),
+        m_channels(channels), m_max_size(max_size) {}
+
+
+    /* Push a bunch of samples into the buffer */
+    size_t push(const T *val, size_t len)
+    {
+        boost::mutex::scoped_lock lock(m_mutex);
+
+        if (m_queue.size() >= m_max_size) {
+            return 0;
+        }
+
+        for (size_t i = 0; i < len; i++) {
+            m_queue.push_back(val[i]);
+        }
+
+        size_t new_size = m_queue.size();
+        lock.unlock();
+
+        //m_condition_variable.notify_one();
+
+        return new_size;
+    }
+
+    bool empty() const
+    {
+        boost::mutex::scoped_lock lock(m_mutex);
+        return m_queue.empty();
+    }
+
+    /* Get len elements, place them into the buf array
+     * Returns the number of elements it was able to take
+     * from the queue
+     */
+    size_t pop(T* buf, size_t len)
+    {
+        boost::mutex::scoped_lock lock(m_mutex);
+
+        size_t ret = 0;
+
+        if (m_queue.size() < len) {
+            size_t i;
+            for (i = 0; i < m_queue.size(); i++) {
+                buf[i] = m_queue[i];
+            }
+
+            ret = i;
+
+            for (; i < len; i++) {
+                buf[i] = 0;
+            }
+
+            m_queue.resize(0);
+        }
+        else {
+            for (size_t i = 0; i < len; i++) {
+                buf[i] = m_queue[i];
+            }
+
+            ret = len;
+
+            m_queue.erase(m_queue.front(), m_queue.front() + len);
+        }
+
+        return ret;
+    }
+
+    /*
+    void wait_and_pop(T& popped_value)
+    {
+        boost::mutex::scoped_lock lock(m_mutex);
+        while(m_queue.size() < m_required_size)
+        {
+            m_condition_variable.wait(lock);
+        }
+
+        popped_value = m_queue.front();
+        m_queue.pop_front();
+    }
+    */
+
+private:
+    std::deque<T> m_queue;
+    mutable boost::mutex m_mutex;
+    //boost::condition_variable m_condition_variable;
+
+    unsigned int m_channels;
+    unsigned int m_bytes_per_sample;
+    size_t m_max_size;
+};
+
+#endif
+