1 files changed, 137 insertions, 0 deletions
diff --git a/lib/buffer_queue_circ.cpp b/lib/buffer_queue_circ.cpp
new file mode 100644
index 0000000..60a2b51
--- /dev/null
+++ b/lib/buffer_queue_circ.cpp
@@ -0,0 +1,137 @@
+// Copyright (C) by Josh Blum. See LICENSE.txt for licensing information.
+
+#include <gras/buffer_queue.hpp>
+#include <gras_impl/debug.hpp>
+#include <boost/circular_buffer.hpp>
+#include <vector>
+
+using namespace gras;
+
+SBuffer make_circular_buffer(const size_t num_bytes); //circular_buffer.cpp
+
+static void buffer_dummy_delete(SBuffer &, const SBuffer /*ref holder*/)
+{
+    //NOP
+}
+
+struct BufferQueueCirc : BufferQueue
+{
+    BufferQueueCirc(const SBufferConfig &config, const size_t num);
+
+    ~BufferQueueCirc(void)
+    {
+        _token.reset();
+        _available_buffers.clear();
+        _returned_buffers.clear();
+    }
+
+    SBuffer &front(void);
+
+    void pop(void);
+
+    void push(const SBuffer &buff);
+
+    bool empty(void) const
+    {
+        return _bytes_avail == 0 or _available_buffers.empty();
+    }
+
+    SBufferToken _token;
+    SBuffer _circ_buff;
+    char *_write_ptr;
+    size_t _bytes_avail;
+    size_t _ack_index;
+    boost::circular_buffer<SBuffer> _available_buffers;
+    std::vector<SBuffer> _returned_buffers;
+    std::vector<size_t> _outgone_bytes;
+
+};
+
+BufferQueueCirc::BufferQueueCirc(const SBufferConfig &config, const size_t num_buffs):
+    _token(config.token),
+    _ack_index(0)
+{
+    //allocate a large buffer
+    const size_t num_bytes = config.length * num_buffs;
+    _circ_buff = make_circular_buffer(num_bytes);
+    _write_ptr = (char *)_circ_buff.get_actual_memory();
+    _bytes_avail = _circ_buff.get_actual_length();
+
+    //create dummy deleter to hold ref to circ buff
+    SBufferDeleter deleter = boost::bind(&buffer_dummy_delete, _1, _circ_buff);
+
+    //allocate pool of sbuffers
+    _available_buffers.set_capacity(num_buffs);
+    _returned_buffers.resize(num_buffs);
+    _outgone_bytes.resize(num_buffs, 0);
+    SBufferConfig sconfig = config;
+    sconfig.deleter = deleter;
+    sconfig.memory = _circ_buff.get_actual_memory();
+    for (size_t i = 0; i < num_buffs; i++)
+    {
+        sconfig.user_index = i;
+        SBuffer buff(sconfig);
+        //buffer derefs and returns to this queue thru token callback
+    }
+}
+
+SBuffer &BufferQueueCirc::front(void)
+{
+    ASSERT(not this->empty());
+    SBuffer &front = _available_buffers.front();
+    ASSERT(front);
+    front->config.memory = _write_ptr;
+    return front;
+}
+
+void BufferQueueCirc::pop(void)
+{
+    ASSERT(not this->empty());
+    SBuffer &front = _available_buffers.front();
+    const size_t num_bytes = front.offset;
+
+    //store number of bytes for buffer return
+    _outgone_bytes[front.get_user_index()] = num_bytes;
+
+    //pop the buffer from internal reference
+    _available_buffers.pop_front();
+
+    //adjust the write pointer
+    _write_ptr += num_bytes;
+
+    //handle circular wrap
+    if (_write_ptr > (char *)_circ_buff.get(_circ_buff.get_actual_length()))
+    {
+        _write_ptr -= _circ_buff.get_actual_length();
+    }
+
+    //subtract out of available bytes
+    ASSERT(_bytes_avail >= num_bytes);
+    _bytes_avail -= num_bytes;
+}
+
+void BufferQueueCirc::push(const SBuffer &buff)
+{
+    _returned_buffers[buff.get_user_index()] = buff;
+
+    //ack starting at the expected index and up
+    while (_returned_buffers[_ack_index])
+    {
+        //return the held bytes to the available
+        _bytes_avail += _outgone_bytes[_ack_index];
+
+        //remove the buffer container into the queue
+        _available_buffers.push_back(_returned_buffers[_ack_index]);
+        _returned_buffers[_ack_index].reset();
+
+        //increment the ack index for the next run
+        if (++_ack_index == _returned_buffers.size()) _ack_index = 0;
+    }
+}
+
+BufferQueueSptr BufferQueue::make_circ(
+    const SBufferConfig &config,
+    const size_t num_buffs
+){
+    return BufferQueueSptr(new BufferQueueCirc(config, num_buffs));
+}