printip.cpp

/******************************************************************************

MIT License

Copyright (c) 2018 Tadeusz Puźniakowski

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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SOFTWARE.

******************************************************************************/

// constants from tutorial https://kapie.com/2016/ssd1306-128x64-bit-oled-display-interfacing-with-raspberry-pi/ by Ken Hughes

#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/i2c-dev.h>
#include <ifaddrs.h>
#include <arpa/inet.h>

#include <string>
#include <vector>
#include <iostream>

#include "font8x8_basic.h"


class display_ssd1306_t {
public:
    std::vector<std::vector<unsigned char>> _display;
    int _addr; ///< device address
    int _handle; ///< file handle to i2c device

    void write_buff(const std::vector < unsigned char > data) {
        if (ioctl(_handle, I2C_SLAVE, _addr) < 0) throw "error in ioctl(_handle, I2C_SLAVE, _addr) < 0";
        else write(_handle, data.data(), data.size());
    }

    void blit() {
        write_buff({0x00,0x21,0x00,0x7F,0x22,0x00,0x07}); // write buffer sequence
        for(auto &line:_display) write_buff(line);
    }

    void put_bit(int x, int y, int c) {
        if ((x < 0) || (x >= 128) || (y < 0) || (y >= 64)) return;
        int prev = _display[y>>3][x+1];
        prev = c*(prev | (1 << (y&7))) | (1-c)*(prev & (~(1 << (y&7))));
        _display[y>>3][x+1] = prev;
    }

    void print_bitmap(int x0, int y0, const unsigned char *p) {
        for (int y = 0; y < 8; y++) {
            int row = p[y];
            for (int x = 0; x < 9; x++) {
                int val = row & 1;
                put_bit(x+x0,y+y0,val);
                row = row >> 1;
            }
        }
    }

    /**
     * @brief Print single digit on a buffer
     * 
     * @param x position x
     * @param y position y
     * @param digit digit. It only supports '0'-'9', '.', ' '
     */
    void print_digit(int x, int y, char digit) {
        const unsigned char *p;
        char i = digit; //0;
        if (i > 128) i = 0;
        p = (unsigned char *)(font8x8_basic[i]);
        print_bitmap(x,y,p);
    }

    void print_digit_string(int x, int y, const std::string s) {
        const char *digits = s.c_str();
        while (*digits) {
            print_digit(x,y,*digits);
            digits++;
            x+=8;
        }
    }


    display_ssd1306_t(const int address_ = 0x3C, const std::string &devfile_ = "/dev/i2c-1") {
        _addr = address_;
        _handle = open(devfile_.c_str(), O_RDWR);
        if (_handle < 0) throw "error opening i2c device";
        write_buff({0x00,0xAE,0xA8,0x3F,0xD3,0x00,0x40,0xA1,0xC8,0xDA,0x12,0x81,0x7F,0xA4,0xA6,0xD5,0x80,0x8D,0x14,0xD9,0x22,0xD8,0x30,0x20,0x00,0xAF}); ///< initialize device
        _display = std::vector<std::vector<unsigned char>>(8,std::vector<unsigned char>(129));
        for(auto &line: _display) line[0] = 0x40; // first byte in each line must be set to 0x040
    }

    virtual ~display_ssd1306_t() {
        close(_handle);
    }
};



std::vector<std::string> get_local_addresses() {
    std::vector<std::string> ipv4_addresses;
    struct ifaddrs *ifaddr, *ifa;
    int family;
    if (getifaddrs(&ifaddr) == -1) {
        throw std::invalid_argument("Error: getifaddrs failed");
        return ipv4_addresses;
    }
    for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
        if (ifa->ifa_addr == NULL)
            continue;
        family = ifa->ifa_addr->sa_family;
        if (family == AF_INET) {
            struct sockaddr_in *ipv4_addr = (struct sockaddr_in *)ifa->ifa_addr;
            char ip_str[INET_ADDRSTRLEN];
            inet_ntop(AF_INET, &(ipv4_addr->sin_addr), ip_str, INET_ADDRSTRLEN);
            if (std::string(ip_str) != std::string("127.0.0.1"))
                ipv4_addresses.push_back(ip_str);
        }
    }
    freeifaddrs(ifaddr);
    return ipv4_addresses;
}


int main() {
    display_ssd1306_t ssddisp;
    ssddisp.print_digit_string(0,0,"Witaj w swiecie     ");
    int y = 9;
    for (auto s : get_local_addresses()) {
        ssddisp.print_digit_string(0,y,s);
        y+= 9;
    }
    ssddisp.blit();
    return 0;
}