Mulog - simple logger for embedded systems

This repository is an attempt to design a simple yet powerful logger that can be used for embedded systems.

Dependencies

• printf: lightweight printf-family implementation suitable for embedded systems
• lwrb: ring buffer implementation suitable for embedded systems (required only in deferred mode)

Usage

CMake FetchContent

include(FetchContent)
# Optional - configure mulog library options
set(MULOG_SINGLE_LOG_LINE_SIZE 256)
set(MULOG_ENABLE_LOCKING OFF)
# Fetch library content
FetchContent_Declare(mulog_library
        GIT_REPOSITORY https://github.com/vpetrigo/mulog.git
        GIT_TAG v12.34.45 # Replace this with a real available version
)
FetchContent_MakeAvailable(mulog_library)

target_link_libraries(<your_target> PRIVATE mulog::mulog)

Optimization

By default, the project does not specify additional optimization flags for the library. To achieve smaller size of an executable, consider adding the following:

• GCC: compile options -ffunction-sections -fdata-sections and linker option -Wl,--gc-sections to garbage collect unused functions/data. This also prevents necessity to define putchar_() function implementation which is a dependency from the printf library

Options

The following options available for library configuration:

Option	Default value	Description
MULOG_ENABLE_TESTING	OFF	Enable tests for mulog library
MULOG_ENABLE_COLOR_OUTPUT	ON	Enable color output
MULOG_ENABLE_TIMESTAMP_OUTPUT	ON	Enable timestamp output for log entries
MULOG_ENABLE_LOCKING	ON	Enable locking mechanism for multithreading/multitasking environment
MULOG_SINGLE_LOG_LINE_SIZE	128	Deferred mode only: Maximum size of a single log line passed to an output callback
MULOG_OUTPUT_HANDLERS	2	Maximum number of output handlers that can be registered
MULOG_CUSTOM_CONFIG	""	Optional path to an external config file
MULOG_ENABLE_DEFERRED_LOGGING	OFF	Enable deferred logging support
MULOG_BUILD_EXAMPLES	OFF	Build examples

config.h can be updated and used along with the MULOG_CUSTOM_CONFIG to provide a path to modified configuration to be used for library build.

Usage example

#include <stdbool.h>
#include <stdio.h>

#include <mulog.h>

static char buffer[256];

unsigned long mulog_config_mulog_timestamp_get(void)
{
    return 0;
}

static void output(const char *buf, const size_t buf_size)
{
    printf("%.*s", (int)buf_size, buf);
}

// required here to facilitate libprintf dependency requirements
void putchar_(char c)
{
    (void)c;
}

int main(void)
{
    mulog_set_log_buffer(buffer, sizeof(buffer));
    mulog_set_log_level(MULOG_LOG_LVL_INFO);
    mulog_add_output(output);

    MULOG_LOG_INFO("Hello");
    MULOG_LOG_DBG("World!");

    return 0;
}

Contribution

---

Contributions are always welcome! If you have an idea, it's best to float it by me before working on it to ensure no effort is wasted. If there's already an open issue for it, knock yourself out.

License

---

<sup>This project is licensed under Apache License, Version 2.0

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in time by you, as defined in the Apache-2.0 license, shall be licensed as above, without any additional terms or conditions.</sup>