io_multiplexer.h

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// Copyright 2024 The Aerospace Corporation.
// This file is a part of SatCat5, licensed under CERN-OHL-W v2 or later.
 
#pragma once
 
#include <satcat5/io_readable.h>
#include <satcat5/io_writeable.h>
 
namespace satcat5 {
    namespace io {
        class MuxPort
            : public satcat5::io::ReadableRedirect
            , public satcat5::io::WriteableRedirect
        {
        public:
            constexpr MuxPort()
                : ReadableRedirect(0), WriteableRedirect(&null_write) {}
 
            void set_callback(satcat5::io::EventListener* callback) override
                { satcat5::io::Readable::set_callback(callback); }
 
        protected:
            friend class satcat5::io::MuxDown;
 
            void attach(Readable* src, Writeable* dst)
                { read_src(src); write_dst(dst); }
        };
 
        class MuxDown : public satcat5::io::EventListener {
        public:
            inline satcat5::io::Readable* port_rd(unsigned idx)
                { return (idx < m_size) ? (m_ports + idx) : 0; }
            inline satcat5::io::Writeable* port_wr(unsigned idx)
                { return (idx < m_size) ? (m_ports + idx) : 0; }
 
            void select(unsigned idx);
 
        protected:
            MuxDown(
                unsigned size, satcat5::io::MuxPort* ports,
                satcat5::io::Readable* src, satcat5::io::Writeable* dst);
            ~MuxDown() SATCAT5_OPTIONAL_DTOR;
 
            // Implement the EventListener API.
            void data_rcvd(satcat5::io::Readable* src) override;
            void data_unlink(satcat5::io::Readable* src) override;
 
            // Pointers to the backing array and the shared port interface.
            const unsigned m_size;
            unsigned m_index;
            satcat5::io::MuxPort* const m_ports;
            satcat5::io::Readable* m_src;
            satcat5::io::Writeable* const m_dst;
        };
 
        class MuxUp
            : public satcat5::io::EventListener
            , public satcat5::io::MuxPort
        {
        public:
            void port_set(unsigned idx, Readable* src, Writeable* dst);
 
            void select(unsigned idx);
 
        protected:
            constexpr MuxUp(unsigned size,
                satcat5::io::Readable** src, satcat5::io::Writeable** dst)
                : m_size(size), m_index(-1), m_src(src), m_dst(dst) {}
            ~MuxUp() SATCAT5_OPTIONAL_DTOR;
 
            // Implement the EventListener API.
            void data_rcvd(satcat5::io::Readable* src) override;
            void data_unlink(satcat5::io::Readable* src) override;
 
            // Pointers to the backing array of port interfaces.
            const unsigned m_size;
            unsigned m_index;
            satcat5::io::Readable** const m_src;
            satcat5::io::Writeable** const m_dst;
        };
 
        template <unsigned SIZE>
        class MuxDownStatic final : public satcat5::io::MuxDown {
        public:
            MuxDownStatic(satcat5::io::Readable* src, satcat5::io::Writeable* dst)
                : MuxDown(SIZE, m_port_array, src, dst) {}
        private:
            satcat5::io::MuxPort m_port_array[SIZE];
        };
 
        template <unsigned SIZE>
        class MuxUpStatic final : public satcat5::io::MuxUp {
        public:
            MuxUpStatic()
                : MuxUp(SIZE, m_src_array, m_dst_array), m_src_array{0}, m_dst_array{0} {}
        private:
            satcat5::io::Readable* m_src_array[SIZE];
            satcat5::io::Writeable* m_dst_array[SIZE];
        };
    }
}