direct.c

#include "ubh.h"

#ifndef PACKET_ESCAPE
    #define PACKET_ESCAPE (uint8_t) 0xff
#endif

void try_dispatch_received_packet();
void USART_SendByte(uint8_t u8Data);
void ub_init_infrastructure();

//Exact duplication of crc8 from `ub.c` (we want to exclude uartbus library but
//this very single function is required to imitate we are a single node bus)

//https://www.ccsinfo.com/forum/viewtopic.php?t=37015
//x^8+x^5+x^4+x^0 //Dallas-Maxim CRC8
uint8_t crc8(uint8_t* data, uint8_t length)
{
    uint8_t crc = 0;
    uint8_t v;
    uint8_t i;
    for(i=0;i<length;++i)
    {
        v = (data[i] ^ crc) & 0xff; 
        crc = 0;
        if(v & 1)
            crc ^= 0x5e; 
        if(v & 2)
            crc ^= 0xbc; 
        if(v & 4)
            crc ^= 0x61; 
        if(v & 8)
            crc ^= 0xc2; 
        if(v & 0x10)
            crc ^= 0x9d; 
        if(v & 0x20)
            crc ^= 0x23; 
        if(v & 0x40)
            crc ^= 0x46; 
        if(v & 0x80)
            crc ^= 0x8c;
    }

    return crc;
}


//fake uartbus strucure and `bus` varaible
struct uartbus{} bus;

uint8_t rando()
{
    return 0;
}

void init_bus()
{
    ub_init_infrastructure();
};

//copied and modified from uartbus_connector.cpp

#include <avr/io.h>


bool mayCut = false;
/*
if(received_ep == MAX_PACKET_SIZE)
    {
        //brake the package manually
        received_ep = 0;
    }
    else
    {
        received_data[received_ep++] = data_byte;
    }
*/
void ub_out_rec_byte(struct uartbus* bus, uint16_t data)
{
    if(data < 0 || data > 255)
    {
        return;
    }
    
    //if we have a pending packet
    if(received)
    {
        return;
    }
    
    if(received_ep >= MAX_PACKET_SIZE)
    {
        received_ep = 0;//break too the long packet
    }
    
    uint8_t b = data;

    if(mayCut)
    {
        if(b == (uint8_t)~PACKET_ESCAPE)
        {
            //new packet received
            received = true;
        }
        else
        {
            received_data[received_ep++] = b;
        }
        mayCut = false;
    }
    else
    {
        if(b == (uint8_t)PACKET_ESCAPE)
        {
            mayCut = true;
        }
        else
        {
            received_data[received_ep++] = b;
        }
    }
}

void try_send_packet()
{
    if(send_size != 0)
    {
        for(uint8_t i=0;i<send_size;++i)
        {
            uint8_t val = send_data[i];
            if(PACKET_ESCAPE == val)
            {
                USART_SendByte((uint8_t)PACKET_ESCAPE);
            }
            USART_SendByte(val);
        }
        USART_SendByte((uint8_t)PACKET_ESCAPE);
        USART_SendByte((uint8_t)~PACKET_ESCAPE);
        
        send_size = 0;
    }
}


void ubh_manage_bus()
{
    try_send_packet();
    try_dispatch_received_packet();
}