From 9f0159f2327b29dda47735fd69aaf5ce2da20d91 Mon Sep 17 00:00:00 2001
From: "Matthias P. Braendli" <matthias.braendli@mpb.li>
Date: Sun, 9 Mar 2014 16:07:01 +0100
Subject: Split AlsaInput into two variants (Threaded/Direct)

---
 src/AlsaDabplus.cpp |  2 +-
 src/AlsaInput.cpp   | 21 ++++++++++----
 src/AlsaInput.h     | 83 +++++++++++++++++++++++++++++++++++++++++------------
 3 files changed, 81 insertions(+), 25 deletions(-)

diff --git a/src/AlsaDabplus.cpp b/src/AlsaDabplus.cpp
index 103a4b2..9c3c759 100644
--- a/src/AlsaDabplus.cpp
+++ b/src/AlsaDabplus.cpp
@@ -256,7 +256,7 @@ int main(int argc, char *argv[]) {
         return 1;
     }
 
-    AlsaInput alsa_in(alsa_device, channels, sample_rate, queue);
+    AlsaInputThreaded alsa_in(alsa_device, channels, sample_rate, queue);
 
     if (alsa_in.prepare() != 0) {
         fprintf(stderr, "Alsa preparation failed\n");
diff --git a/src/AlsaInput.cpp b/src/AlsaInput.cpp
index 8b6f790..14f4524 100644
--- a/src/AlsaInput.cpp
+++ b/src/AlsaInput.cpp
@@ -101,7 +101,7 @@ int AlsaInput::prepare()
     return 0;
 }
 
-size_t AlsaInput::read(uint8_t* buf, snd_pcm_uframes_t length)
+size_t AlsaInput::m_read(uint8_t* buf, snd_pcm_uframes_t length)
 {
     int i;
     int err;
@@ -121,19 +121,30 @@ size_t AlsaInput::read(uint8_t* buf, snd_pcm_uframes_t length)
     return err;
 }
 
-void AlsaInput::start()
+void AlsaInputThreaded::start()
 {
     m_running = true;
-    m_thread = boost::thread(&AlsaInput::process, this);
+    m_thread = boost::thread(&AlsaInputThreaded::process, this);
 }
 
-void AlsaInput::process()
+void AlsaInputThreaded::process()
 {
     uint8_t samplebuf[NUM_SAMPLES_PER_CALL * BYTES_PER_SAMPLE * m_channels];
     while (m_running) {
-        size_t n = read(samplebuf, NUM_SAMPLES_PER_CALL);
+        size_t n = m_read(samplebuf, NUM_SAMPLES_PER_CALL);
 
         m_queue.push(samplebuf, BYTES_PER_SAMPLE*m_channels*n);
     }
 }
 
+
+size_t AlsaInputDirect::read(uint8_t* buf, size_t length)
+{
+    int bytes_per_frame = m_channels * BYTES_PER_SAMPLE;
+    assert(length % bytes_per_frame == 0);
+
+    size_t read = m_read(buf, length / bytes_per_frame);
+
+    return read * bytes_per_frame;
+}
+
diff --git a/src/AlsaInput.h b/src/AlsaInput.h
index c1e3e9b..eb02ec1 100644
--- a/src/AlsaInput.h
+++ b/src/AlsaInput.h
@@ -40,22 +40,13 @@ class AlsaInput
     public:
         AlsaInput(const string& alsa_dev,
                 unsigned int channels,
-                unsigned int rate,
-                SampleQueue<uint8_t>& queue) :
-            m_running(false),
+                unsigned int rate) :
             m_alsa_dev(alsa_dev),
             m_channels(channels),
             m_rate(rate),
-            m_queue(queue),
             m_alsa_handle(NULL) { }
 
-        ~AlsaInput()
-        {
-            if (m_running) {
-                m_running = false;
-                m_thread.interrupt();
-                m_thread.join();
-            }
+        ~AlsaInput() {
 
             if (m_alsa_handle) {
                 snd_pcm_abort(m_alsa_handle);
@@ -63,26 +54,80 @@ class AlsaInput
             }
         }
 
+        /* Prepare the audio input */
         int prepare();
 
-        void start();
+        virtual void start() = 0;
+
+    protected:
+        size_t m_read(uint8_t* buf, snd_pcm_uframes_t length);
+
+        string m_alsa_dev;
+        unsigned int m_channels;
+        unsigned int m_rate;
+
+        snd_pcm_t *m_alsa_handle;
 
     private:
-        AlsaInput(const AlsaInput& other) : m_queue(other.m_queue) {}
+        AlsaInput(const AlsaInput& other) {}
+};
+
+class AlsaInputDirect : public AlsaInput
+{
+    public:
+        AlsaInputDirect(const string& alsa_dev,
+                unsigned int channels,
+                unsigned int rate) :
+            AlsaInput(alsa_dev, channels, rate) { }
+
+        virtual void start() { };
+
+        /* Read length Bytes from from the alsa device.
+         * length must be a multiple of channels * bytes_per_sample.
+         *
+         * Returns the number of bytes read.
+         */
+        size_t read(uint8_t* buf, size_t length);
+
+    private:
+        AlsaInputDirect(const AlsaInputDirect& other) :
+            AlsaInput("", 0, 0) { }
+};
+
+class AlsaInputThreaded : public AlsaInput
+{
+    public:
+        AlsaInputThreaded(const string& alsa_dev,
+                unsigned int channels,
+                unsigned int rate,
+                SampleQueue<uint8_t>& queue) :
+            AlsaInput(alsa_dev, channels, rate),
+            m_running(false),
+            m_queue(queue) { }
+
+        ~AlsaInputThreaded()
+        {
+            if (m_running) {
+                m_running = false;
+                m_thread.interrupt();
+                m_thread.join();
+            }
+        }
+
+        virtual void start();
+
+    private:
+        AlsaInputThreaded(const AlsaInputThreaded& other) :
+            AlsaInput("", 0, 0),
+            m_queue(other.m_queue) {}
 
-        size_t read(uint8_t* buf, snd_pcm_uframes_t length);
         void process();
 
         bool m_running;
         boost::thread m_thread;
-        string m_alsa_dev;
-        unsigned int m_channels;
-        unsigned int m_rate;
 
         SampleQueue<uint8_t>& m_queue;
 
-        snd_pcm_t *m_alsa_handle;
-
 };
 
 #endif
-- 
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