1 files changed, 116 insertions, 0 deletions
diff --git a/gnuradio-runtime/include/gnuradio/buffer_double_mapped.h b/gnuradio-runtime/include/gnuradio/buffer_double_mapped.h
new file mode 100644
index 0000000000..b8cc7cdc87
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+++ b/gnuradio-runtime/include/gnuradio/buffer_double_mapped.h
@@ -0,0 +1,116 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2020 Free Software Foundation, Inc.
+ *
+ * This file is part of GNU Radio
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ */
+
+#ifndef INCLUDED_GR_RUNTIME_BUFFER_DOUBLE_MAPPED_H
+#define INCLUDED_GR_RUNTIME_BUFFER_DOUBLE_MAPPED_H
+
+#include <gnuradio/api.h>
+#include <gnuradio/buffer.h>
+#include <gnuradio/logger.h>
+#include <gnuradio/runtime_types.h>
+
+namespace gr {
+
+class vmcircbuf;
+
+/*!
+ * \brief Note this function is only used and really intended to be used in
+ *  qa_buffer.cc for the unit tests of buffer_double_mapped.
+ *
+ */
+GR_RUNTIME_API buffer_sptr make_buffer_double_mapped(int nitems,
+                                                     size_t sizeof_item,
+                                                     uint64_t downstream_lcm_nitems,
+                                                     block_sptr link = block_sptr());
+
+/*!
+ * \brief Single writer, multiple reader fifo.
+ * \ingroup internal
+ */
+class GR_RUNTIME_API buffer_double_mapped : public buffer
+{
+public:
+    gr::logger_ptr d_logger;
+    gr::logger_ptr d_debug_logger;
+
+    virtual ~buffer_double_mapped();
+
+    /*!
+     * \brief return number of items worth of space available for writing
+     */
+    virtual int space_available();
+
+protected:
+    /*!
+     * sets d_vmcircbuf, d_base, d_bufsize.
+     * returns true iff successful.
+     */
+    bool allocate_buffer(int nitems, size_t sizeof_item);
+
+    virtual unsigned index_add(unsigned a, unsigned b)
+    {
+        unsigned s = a + b;
+
+        if (s >= d_bufsize)
+            s -= d_bufsize;
+
+        assert(s < d_bufsize);
+        return s;
+    }
+
+    virtual unsigned index_sub(unsigned a, unsigned b)
+    {
+        int s = a - b;
+
+        if (s < 0)
+            s += d_bufsize;
+
+        assert((unsigned)s < d_bufsize);
+        return s;
+    }
+
+private:
+    friend class buffer_reader;
+
+    friend GR_RUNTIME_API buffer_sptr make_buffer(int nitems,
+                                                  size_t sizeof_item,
+                                                  uint64_t downstream_lcm_nitems,
+                                                  block_sptr link,
+                                                  block_sptr buf_owner);
+    friend GR_RUNTIME_API buffer_sptr make_buffer_double_mapped(
+        int nitems, size_t sizeof_item, uint64_t downstream_lcm_nitems, block_sptr link);
+
+    std::unique_ptr<gr::vmcircbuf> d_vmcircbuf;
+
+    /*!
+     * \brief constructor is private.  Use gr_make_buffer to create instances.
+     *
+     * Allocate a buffer that holds at least \p nitems of size \p sizeof_item.
+     *
+     * \param nitems is the minimum number of items the buffer will hold.
+     * \param sizeof_item is the size of an item in bytes.
+     * \param downstream_lcm_nitems is the least common multiple of the items to
+     *                              read by downstream blocks
+     * \param link is the block that writes to this buffer.
+     *
+     * The total size of the buffer will be rounded up to a system
+     * dependent boundary.  This is typically the system page size, but
+     * under MS windows is 64KB.
+     */
+    buffer_double_mapped(int nitems,
+                         size_t sizeof_item,
+                         uint64_t downstream_lcm_nitems,
+                         block_sptr link);
+};
+
+} /* namespace gr */
+
+
+#endif /* INCLUDED_GR_RUNTIME_BUFFER_DOUBLE_MAPPED_H */