log.h File Reference

System logging header. More...

Detailed Description

System logging header.

This header offers a bunch of "LOG_*" functions that, with the default implementation, just use printf, but honour a verbosity level.

If desired, it is possible to implement a log module which then will be used instead the default printf-based implementation. In order to do so, the log module has to

  1. provide "log_module.h"
  2. have a name starting with "log_" or depend on the pseudo-module LOG,
  3. implement log_write()

See "sys/log/log_printfnoformat" for an example.

Kaspar Schleiser kaspa.nosp@m.r@sc.nosp@m.hleis.nosp@m.er.d.nosp@m.e

Definition in file log.h.

#include <stdio.h>
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#define log_write(level, ...)   printf(__VA_ARGS__)
 Default log_write function, just maps to printf.
 Default log level define.
#define LOG(level, ...)
 Log message if level <= LOG_LEVEL. More...
enum  {
 defined log levels More...

Logging convenience defines

#define LOG_ERROR(...)   LOG(LOG_ERROR, __VA_ARGS__)
#define LOG_INFO(...)   LOG(LOG_INFO, __VA_ARGS__)
#define LOG_DEBUG(...)   LOG(LOG_DEBUG, __VA_ARGS__)

Macro Definition Documentation


#define LOG (   level,
do { \
if ((level) <= LOG_LEVEL) log_write((level), __VA_ARGS__); } while (0U)
#define LOG_LEVEL
Default log level define.
Definition: log.h:70
#define log_write(level,...)
Default log_write function, just maps to printf.
Definition: log.h:105

Log message if level <= LOG_LEVEL.

Definition at line 83 of file log.h.

Enumeration Type Documentation

◆ anonymous enum

anonymous enum

defined log levels

These are the logging levels a user can choose. The idea is to set LOG_LEVEL to one of these values in the application's Makefile. That will restrict output of log statements to those with equal or lower log level.

The default log level is LOG_INFO, which will print every message.

The log function calls of filtered messages will be optimized out at compile time, so a lower log level might result in smaller code size.


Lowest log level, will output nothing.


Error log level, will print only critical, non-recoverable errors like hardware initialization failures.


Warning log level, will print warning messages for temporary errors.


Informational log level, will print purely informational messages like successful system bootup, network link state, ...


Debug log level, printing developer stuff considered too verbose for production use.


print everything

Definition at line 51 of file log.h.