/* -*- c++ -*- */
/*
 * Copyright 2003,2013 Free Software Foundation, Inc.
 *
 * This file is part of GNU Radio
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 */

#ifndef GR_VMCIRCBUF_H
#define GR_VMCIRCBUF_H

#include <gnuradio/api.h>
#include <gnuradio/logger.h>
#include <gnuradio/prefs.h>
#include <gnuradio/thread/thread.h>
#include <vector>

extern gr::thread::mutex s_vm_mutex;

namespace gr {

/*!
 * \brief abstract class to implement doubly mapped virtual memory circular buffers
 * \ingroup internal
 */
class GR_RUNTIME_API vmcircbuf
{
protected:
    int d_size;
    char* d_base;
    logger_ptr d_logger;
    logger_ptr d_debug_logger;

    // CREATORS
    vmcircbuf(int size) : d_size(size), d_base(0)
    {
        gr::configure_default_loggers(d_logger, d_debug_logger, "gr::vmcircbuf");
    };

public:
    virtual ~vmcircbuf();

    // ACCESSORS
    void* pointer_to_first_copy() const { return d_base; }
    void* pointer_to_second_copy() const { return d_base + d_size; }
};

/*!
 * \brief abstract factory for creating circular buffers
 */
class GR_RUNTIME_API vmcircbuf_factory
{
protected:
    vmcircbuf_factory(){};
    virtual ~vmcircbuf_factory();

public:
    /*!
     * \brief return name of this factory
     */
    virtual const char* name() const = 0;

    /*!
     * \brief return granularity of mapping, typically equal to page size
     */
    virtual int granularity() = 0;

    /*!
     * \brief return a gr::vmcircbuf, or 0 if unable.
     *
     * Call this to create a doubly mapped circular buffer.
     */
    virtual vmcircbuf* make(int size) = 0;
};

/*
 * \brief pulls together all implementations of gr::vmcircbuf
 */
class GR_RUNTIME_API vmcircbuf_sysconfig
{
public:
    /*
     * \brief return the single instance of the default factory.
     *
     * returns the default factory to use if it's already defined,
     * else find the first working factory and use it.
     */
    static vmcircbuf_factory* get_default_factory();

    static int granularity() { return get_default_factory()->granularity(); }
    static vmcircbuf* make(int size) { return get_default_factory()->make(size); }

    // N.B. not all factories are guaranteed to work.
    // It's too hard to check everything at config time, so we check at runtime
    static std::vector<vmcircbuf_factory*> all_factories();

    // make this factory the default
    static void set_default_factory(vmcircbuf_factory* f);

    /*!
     * \brief  Does this factory really work?
     *
     * verbose = 0: silent
     * verbose = 1: names of factories tested and results
     * verbose = 2: all intermediate results
     */
    static bool test_factory(vmcircbuf_factory* f, int verbose);

    /*!
     * \brief Test all factories, return true if at least one of them works
     * verbose = 0: silent
     * verbose = 1: names of factories tested and results
     * verbose = 2: all intermediate results
     */
    static bool test_all_factories(int verbose);
};

} /* namespace gr */

#endif /* GR_VMCIRCBUF_H */
