# Implementing the library logging macros
<a name="afr-library-logging-macros"></a>

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](https://www.freertos.org/logging.html) on FreeRTOS.org for implementation specifics. You can see an implementation in this [example](https://github.com/FreeRTOS/lab-iot-reference-nxp-rt1060/tree/main/examples/common/logging).

## Testing
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+ 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`.