From f3484dd17fb20493cdbe72a8bdbeb77ab3ee57ff Mon Sep 17 00:00:00 2001
From: Muneeb Ahmed <54290492+muneebahmed10@users.noreply.github.com>
Date: Wed, 9 Sep 2020 15:18:12 -0700
Subject: [PATCH] Add documentation for MISRA deviations (#25)

* Add documentation for MISRA deviations
---
 MISRA.md | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 MISRA.md

diff --git a/MISRA.md b/MISRA.md
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+# MISRA Compliance
+
+The MQTT library files conform to the [MISRA C:2012](https://www.misra.org.uk/MISRAHome/MISRAC2012/tabid/196/Default.aspx)
+guidelines, with some noted exceptions. Compliance is checked with Coverity static analysis.
+Deviations from the MISRA standard are listed below:
+
+### Ignored by [Coverity Configuration](https://github.com/aws/aws-iot-device-sdk-embedded-C/blob/master/tools/coverity/misra.config)
+| Deviation | Category | Justification |
+| :-: | :-: | :-: |
+| Directive 4.5 | Advisory | Allow names that MISRA considers ambiguous (such as LogInfo and LogError) |
+| Directive 4.8 | Advisory | Allow inclusion of unused types. Header files for a specific port, which are needed by all files, may define types that are not used by a specific file. |
+| Directive 4.9 | Advisory | Allow inclusion of function like macros. The `assert` macro is used throughout the library for parameter validation, and logging is done using function like macros. |
+| Rule 2.4 | Advisory | Allow unused tags. Some compilers warn if types are not tagged. |
+| Rule 2.5 | Advisory | Allow unused macros. Library headers may define macros intended for the application's use, but are not used by a specific file. |
+| Rule 3.1 | Required | Allow nested comments. C++ style `//` comments are used in example code within Doxygen documentation blocks. |
+| Rule 11.5 | Advisory | Allow casts from `void *`. Fields such as publish payloads are passed as `void *` and must be cast to the correct data type before use. |
+| Rule 21.1 | Required | Allow use of all macro names. For compatibility, some macros introduced in C99 are defined for use with C90 compilers. |
+| Rule 21.2 | Required | Allow use of all macro and identifier names. For compatibility, some macros introduced in C99 are defined for use with C90 compilers. |
+
+### Flagged by Coverity
+| Deviation | Category | Justification |
+| :-: | :-: | :-: |
+| Rule 2.3 | Advisory | The `MQTTSubAckStatus_t` enum is unused in our source files, as it is intended for a user to use when parsing a subscription acknowledgment's response codes. |
+| Rule 8.7 | Advisory | API functions are not used by the library outside of the files they are defined; however, they must be externally visible in order to be used by an application. |
+
+### Suppressed with Coverity Comments
+*None.*