libs/nmc/include/nmc_msg_builder.H

Go to the documentation of this file.

// Copyright (C) 2004 Pablo Mejia


#ifndef NMC_MSG_BUILDER_H
#define NMC_MSG_BUILDER_H


#include "endian.H"


#include <cassert>
#include <cstring>


namespace nmc
{
        using namespace endian;

        class msg_builder_t
        {
        public:
                msg_builder_t ();
                virtual ~msg_builder_t () {};

                static unsigned const MAX_MSG_SIZE                      = 20;

                unsigned build (u8_t address, u8_t *data, unsigned max_size);

        protected:
                static unsigned const ENVELOPE_SIZE                     = 4;
                static unsigned const HEADER_SIZE                       = 3;
                static unsigned const FOOTER_SIZE                       = 1;

                static unsigned const ADDRESS_OFFSET                    = 1;
                static unsigned const COMMAND_OFFSET                    = 2;

                static u8_t const STX                                   = 0xAA;

                static u8_t calc_crc (u8_t const *data, unsigned size);

                unsigned m_offset;

                u8_t *m_data;
                unsigned m_max_size;

                template <typename T>
                void encode (T const &v)
                {
                        assert ((m_offset + sizeof (v)) <= m_max_size);
                        htole (v, m_data + m_offset);
                        m_offset += sizeof (v);
                }

                void encode (void *data, unsigned size)
                {
                        assert ((m_offset + size) <= m_max_size);
                        memcpy (m_data + m_offset, data, size);
                        m_offset += size;
                }

                virtual u8_t _build (void) = 0;
        };

        class set_address_builder_t : public msg_builder_t
        {
        public:
                set_address_builder_t () :
                        m_module_address (0), m_group_address (0) {}

                void module_address (u8_t address)
                        { m_module_address = address; }
                void group_address (u8_t address)
                        { m_group_address = address; }

        protected:
                u8_t _build (void);

                u8_t m_module_address;
                u8_t m_group_address;
        };

        class set_baud_rate_builder_t : public msg_builder_t
        {
        public:
                enum baud_t
                {
                        BAUD_9600                                       = 129,
                        BAUD_19200                                      = 63,
                        BAUD_57600                                      = 20,
                        BAUD_115200                                     = 10,
                };

                set_baud_rate_builder_t () : m_baud (BAUD_19200) {}

                void baud_rate (baud_t baud) { m_baud = baud; }

        protected:
                u8_t _build (void);

                baud_t m_baud;
        };

        class no_op_builder_t : public msg_builder_t
        {
        protected:
                u8_t _build (void);
        };

        class hard_reset_builder_t : public msg_builder_t
        {
        protected:
                u8_t _build (void);
        };
};


#endif

---