Random stuff I keep doing to learn about new topics, packages, languages, frameworks and whatever else is out there#

Table of Contents#

Building Paho Library and writing MQTT Client in C
Fota server in python, punching CRC to Bin and other CRC related scripts
Service Tool for 2G telematic using PyQt5
A work timer watchdog created in C using GTK3
Post Build program for boot_info and CRC punch
CMake based buildsystem for MC25 OpenCPU Quectel
Bumblenet - A Network Library (Incomplete)
Data Structures Algorithms Practice

Branches:

mqtt-client-sub #

Theme: The requirement was to provide a firmware for testing EC20 Modem. The telematics device connects to test.mosquitto.org public broker and publishes packet of size 60kB (default, configurable) at interval of 30secs (default, configurable).

Chats with ChatGPT

Features:

I had already used paho mqtt library on python and mqtt_server.py script would have been enough.
I decided to work with the C version of paho mqtt. Compiled the paho.mqtt.c from source and as well as using vcpkg.
I learned to use CMake with different compilers such as Clang (C:/Program Files (x86)/Microsoft Visual Studio/2022/BuildTools/VC/Tools/Llvm/bin/clang.exe) and GCC (C:/msys64/ucrt64/bin/gcc.exe)
Wrote my own CMakeLists.txt.

File Details:

1. hexdump #

Contains a function to print or dump the content of a buffer in hex format. Compiling the hexdump.c file:

cl .\hexdump\hexdump.c /I .\hexdump\ /c /Fo.\hexdump\hexdump.o
clang -c .\hexdump\hexdump.c -o .\hexdump\hexdump.o
gcc -c hexdump/hexdump.c -o hexdump/hexdump.o

One can add default Pre-Processor macro value in CMakeLists.txt like this

# Define NUMCOLS during the build (default value is 24)
set(NUMCOLS 24 CACHE INTEGER "Number of columns in hexdump")

# Pass NUMCOLS as preprocessor definition
target_compile_definitions(${target_name} PRIVATE NUMCOLS=${NUMCOLS})

2. mkPktRand #

Creates a random buffer for given size using XOR Shift random number generator.

32 Bit XOR Shift RNG

static void generatRandomBuffer(uint8_t buffer[], size_t size)
{
    uint32_t *ptr = (uint32_t *)buffer;
    size_t numIterations = size / sizeof(uint32_t);
    for (size_t i = 0; i < numIterations; ++i) {
        g_randSeed ^= (g_randSeed << 13);
        g_randSeed ^= (g_randSeed >> 17);
        g_randSeed ^= (g_randSeed << 5);
        ptr[i] = g_randSeed;
    }
}

3. mqtt_client.c#

This is the main file that creates a client with(out) SSL, connetcs to broker and subcribes to a topic. This file uses the paho.mqtt.c library and the hexdump.

Also, \(\text{ceil}(\frac{a}{b}) = \frac{a+b-1}{b}\)

Logging to file as well as console.

/**
 * The delay in log file updates may be due to output buffering. By default,
 * `printf` buffers output, delaying the write to the console or file until the
 * program exits. To address this, use `fflush(stdout)` and `fflush(logfile)` 
 * after printf and fprintf to ensure immediate writing to both console and file.
*/
#define PRINT(format, ...) do { printf(format, ##__VA_ARGS__); fprintf(logfile, format, ##__VA_ARGS__); fflush(stdout); fflush(logfile); } while (0)

Compiling mqtt_client.c file

GCC

gcc mqtt_client.c -I eclipse-paho-mqtt-c/include/ -I hexdump/ -L eclipse-paho-mqtt-c/lib/ hexdump/hexdump.o -lpaho-mqtt3cs-static

cl (MSVC)

cl .\mqtt_client.c /I .\hexdump\ /I C:\dev\vcpkg\packages\paho-mqtt_x64-windows\include\ /I C:\dev\vcpkg\packages\openssl_x64-windows\include\ /link C:\dev\vcpkg\packages\paho-mqtt_x64-windows\lib\paho-mqtt3cs.lib .\hexdump\hexdump.o

Clang

clang .\mqtt_client.c -I 'C:\dev\vcpkg\packages\paho-mqtt_x64-windows\include\' -I .\hexdump\ -L C:\dev\vcpkg\packages\paho-mqtt_x64-windows\lib\ -l paho-mqtt3cs .\hexdump\hexdump.o -o .\mqtt_client.exe

Refernce: MQTTClient_subscribe.c

4. CMakeLists.txt #

Used to create my package. Also see CMakeLists.txt.bak wich uses vcpkg cmake toolchain.

Also learned that PreLoad.cmake runs before running the CMakeLists.txt. (Ref: https://stackoverflow.com/a/45247784).

So PreLoad.cmake contains: set (CMAKE_GENERATOR "MSYS Makefiles" CACHE INTERNAL "" FORCE)

Running cmake:

cmake .. -DCMAKE_C_COMPILER='C:/Program Files (x86)/Microsoft Visual Studio/2022/BuildTools/VC/Tools/Llvm/bin/clang.exe'
cmake .. -G "MSYS Makefiles" -DCMAKE_C_COMPILER=C:/msys64/ucrt64/bin/gcc.exe -DCMAKE_AR=C:/msys64/ucrt64/bin/ar.exe

5. cmake_command_for_building_paho.bat/sh #

The command I used to build paho.mqtt.c

6. mqtt_server.py #

The first thing I wrote which satisfies the requirements in python file

Auto-starts on Windows boot.
Asks user for confirmation or input of work start time.
Calculates shutdown time = start_time + 9h30m - 15min.
Creates a scheduled task (stop_tasks.exe) at the calculated time using schtasks.

2. `stop_tasks.c`#

Launches a warning popup (Window’s blue colored screen with text).
Starts a 15-minute GTK3 countdown timer.
When timer hits 0:
- Kills specified applications (e.g., VSCode, Edge, etc.)
- Shuts down the PC.

bootinfo-and-appcrc #

Performs post build tasks

Generate bin and hex files from elf frile created from project compilation
Puches CRC32 MPEG-2 at the end of the binary file.
Creates boot_info_data.c file with structure containing firmware related metadata such as BL start address, APP start address, lenght, crc, debug flags, etc.
Provides a linker script and a make file to compile the boot information file into boot_info.hex
Clang Format file

Important Files’ Details:

1. crc32_bootinfo.cpp#

CPP program that reads binary file, calculates CRC32 and appends it. Generates boot_info_data.c file and also 3 other files, two srec commad files, crc32.bin (a 4 byte size file).

Using constexpr to create a crc table

constexpr uint32_t POLYNOMIAL = 0x04C11DB7;
constexpr auto crc_table = [] {
    std::array<uint32_t, 256> table{};
    for (uint32_t i = 0; i < 256; i++) {
        uint32_t crc = i << 24;
        for (int j = 0; j < 8; j++)
            crc = (crc << 1) ^ (crc & 0x80000000 ? POLYNOMIAL : 0);
        table[i] = crc;
    }
    return table;
}();

Learnt about SFINAE and unnecessarily used std::enable_if for crc function.

template <typename T>
using crc32_result_t = typename std::enable_if<std::is_integral<T>::value, uint32_t>::type;

template <typename T>
crc32_result_t<T> crc32(const T *data, size_t size);


template <typename T>
crc32_result_t<T> crc32(const T *data, size_t size)
{
    uint32_t crc = 0xFFFFFFFF;
    for (size_t i = 0; i < size; ++i) {
        uint8_t index = ((crc >> 24) ^ static_cast<uint8_t>(data[i])) & 0xFF;
        crc = crc_table[index] ^ (crc << 8);
    }
    return crc;
}

Compilation:

clang crc32_bootinfo.cpp \
        -std=c++20 \
        -Wall -Wpedantic -Wextra \
        -O3 \
        -o generate_bootinfo_file.exe

2. boot_info.mk #

Makefile that uses toochain compiler for making boot_info.hex.

{CG_TOOL_MAKE} -f boot_info.mk -k -j 8 all -O

3. linker.cmd #

Linker file to place boot_info strcture in proper memory address.

Random stuff I keep doing to learn about new topics, packages, languages, frameworks and whatever else is out there#

Table of Contents#

mqtt-client-sub #

1. hexdump #

2. mkPktRand #

3. mqtt_client.c#

4. CMakeLists.txt #

5. cmake_command_for_building_paho.bat/sh #

6. mqtt_server.py #

server-fota-crc-multithreading #

tcu-2g-service-tool-dealer #

task-control-gtk3 #

1. `schedule_task.c`#

2. `stop_tasks.c`#

bootinfo-and-appcrc #

1. crc32_bootinfo.cpp#

2. boot_info.mk #

3. linker.cmd #

cmake-build-embedded #

network-library-bumblenet #

data-structures-algorithms #

Random stuff I keep doing to learn about new topics, packages, languages, frameworks and whatever else is out there#

Table of Contents#

1. hexdump#

2. mkPktRand#

3. mqtt_client.c#

4. CMakeLists.txt#

5. cmake_command_for_building_paho.bat/sh#

6. mqtt_server.py#

1. schedule_task.c#

2. stop_tasks.c#

1. crc32_bootinfo.cpp#

2. boot_info.mk#

3. linker.cmd#

1. hexdump #

2. mkPktRand #

4. CMakeLists.txt #

5. cmake_command_for_building_paho.bat/sh #

6. mqtt_server.py #

1. `schedule_task.c`#

2. `stop_tasks.c`#

2. boot_info.mk #

3. linker.cmd #