Implementing the library logging macros

The FreeRTOS libraries use the following logging macros, listed in increasing order of verbosity.

LogError
LogWarn
LogInfo
LogDebug

A definition for all the macros must be provided. The recommendations are:

Macros should support C89 style logging.
Logging should be thread safe. Log lines from multiple tasks must not interleave with each other.
Logging APIs must not block, and must free application tasks from blocking on I/O.

Refer to the Logging Functionality on FreeRTOS.org for implementation specifics. You can see an implementation in this example.

Testing

Run a test with multiple tasks to verify logs do not interleave.
Run a test to verify that the logging APIs do not block on I/O.
Test logging macros with various standards, such as C89,C99 style logging.
Test logging macros by setting different log levels, such as Debug, Info, Error, and Warning.