codec_slip.h

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// Copyright 2021-2025 The Aerospace Corporation.
// This file is a part of SatCat5, licensed under CERN-OHL-W v2 or later.
 
#pragma once
 
#include <satcat5/io_buffer.h>
#include <satcat5/pkt_buffer.h>
 
// Default size parameters
// (Must be large enough for one full-size Ethernet frame + metadata,
//  larger sizes are fine if you have the memory for it.)
#ifndef SATCAT5_SLIP_BUFFSIZE
#define SATCAT5_SLIP_BUFFSIZE   1600    // One full-size Ethernet frame
#endif
 
#ifndef SATCAT5_SLIP_PACKETS
#define SATCAT5_SLIP_PACKETS    32      // ...or many smaller frames
#endif
 
namespace satcat5 {
    namespace io {
        class SlipEncoder : public satcat5::io::Writeable {
        public:
            explicit SlipEncoder(satcat5::io::Writeable* dst);
 
            // Implement required API from Writeable:
            unsigned get_write_space() const override;
            bool write_finalize() override;
            void write_overflow() override;
 
        private:
            // Implement required API from Writeable:
            void write_next(u8 data) override;
 
            // Internal state:
            satcat5::io::Writeable* const m_dst;    // Output object
            bool m_overflow;
        };
 
        class SlipDecoder : public satcat5::io::Writeable {
        public:
            explicit SlipDecoder(satcat5::io::Writeable* dst);
 
            // Implement required API from Writeable:
            unsigned get_write_space() const override;
 
        private:
            // Implement required API from Writeable:
            void write_next(u8 data) override;
            void write_overflow() override;
 
            // Internal state:
            enum class State {SLIP_RDY, SLIP_ESC, SLIP_EOF, SLIP_ERR};
            satcat5::io::Writeable* const m_dst;        // Output object
            satcat5::io::SlipDecoder::State m_state;    // Decoder state
        };
 
        class SlipCodec
            : public satcat5::io::SlipEncoder
            , public satcat5::io::ReadableRedirect
        {
        public:
            SlipCodec(
                satcat5::io::Writeable* dst,
                satcat5::io::Readable* src);
 
        protected:
            satcat5::io::PacketBuffer m_buff;       
            satcat5::io::SlipDecoder m_decode;      
            satcat5::io::BufferedCopy m_copy;       
            u8 m_rawbuff[SATCAT5_SLIP_BUFFSIZE];    
        };
 
        class SlipCodecInverse
            : public satcat5::io::SlipDecoder
            , public satcat5::io::ReadableRedirect
        {
        public:
            SlipCodecInverse(
                satcat5::io::Writeable* dst,
                satcat5::io::Readable* src);
 
        protected:
            satcat5::io::PacketBuffer m_buff;       
            satcat5::io::SlipEncoder m_encode;      
            satcat5::io::BufferedCopy m_copy;       
            u8 m_rawbuff[SATCAT5_SLIP_BUFFSIZE];    
        };
    }
}