Manual

MISRA Compliance 🔗

MISRA C is a widely accepted model for best practices used by automotive, telecom, aerospace, medical, and other critical industries. Unicorn honors all Mandatory, most Required, and most Advisory rules defined by MIRSA C:2012. This page documents compliance with MISRA C:2012 and documents all deviations.

Conformance to most MISRA rules is verified with static analysis tools. Readers are encouraged to run their own static analysis tools to verify conformance and that noted deviations are acceptable.

If you believe there is a MISRA violation and/or an inaccuracy in the compliance table, then please report it here.

Compliance Summary Table 🔗

If Unicorn is compliant with a directive or rule then the Compliance column will begin with the text “Compliant” optionally followed by the verification method in parentheses. If no verification method is listed, then static analysis is assumed (this is how most rules are verified). If Unicorn is non-compliant with a directive or rule then the Compliance column will begin with the text “Non-compliant” in bold followed by documentation explaining why.

The MISRA C:2012 rule texts can not be freely distributed therefore the compliance summary table lists the rule number, but omits the description. It is assumed the reader has access to the MISRA C:2012 standard and can cross-reference the rule numbers with the standard.

Implementation 🔗

Directive Category Compliance
D1.1 Required Compliant (manually verified)

Compilation and Build 🔗

Directive Category Compliance
D2.1 Required Compliant (verified with GCC, Clang, and MSVC)

Requirements Traceability 🔗

Directive Category Compliance
D3.1 Required Compliant (manually verified)

Code Design 🔗

Directive Category Compliance
D4.1 Required Compliant (manually verified)
D4.2 Advisory Compliant (Unicorn does not use assembly language)
D4.3 Required Compliant (Unicorn does not use assembly language)
D4.4 Advisory Compliant (manually verified)
D4.5 Advisory Compliant (manually verified)
D4.6 Advisory Compliant (manually verified)
D4.7 Required Compliant (manually verified)
D4.8 Advisory Non-compliant [1]
D4.9 Advisory Compliant (manually verified) [2]
D4.10 Required Compliant (manually verified)
D4.11 Required Compliant (verified by unit tests)
D4.12 Required Compliant (manually verified)
D4.13 Advisory Compliant (manually verified)

[1] The programmatically generated Unicode data tables are collected into a single header/source amalgamation in the commercial implementation of Unicorn. The generated header is included by multiple translation units, but each translation unit only uses a subset of the generated definitions.

[2] Where a function-like macro should become a function is a trade-off between code size and execution speed. In Unicorn, most function-like macros are small expressions and programmatically generated.

Standard C Environment 🔗

Rule Category Compliance
1.1 Required Compliant
1.2 Required Compliant (verified by compiling with Clang's -pedantic flag)
1.3 Required Compliant (verified by Clang's undefined behavior sanitizer)

Unused Code 🔗

Rule Category Compliance
2.1 Required Compliant
2.2 Required Compliant
2.3 Advisory Compliant
2.4 Advisory Compliant
2.5 Advisory Compliant [1]
2.6 Advisory Compliant
2.7 Advisory Compliant

[1] Some macros in unicorn.h are part of the public API, but are not used internally by the library. Static analysis tools may report these macros as being unused, but this is a false positive.

Comments 🔗

Rule Category Compliance
3.1 Required Compliant
3.2 Required Compliant

Character Sets and Lexical Conventions 🔗

Rule Category Compliance
4.1 Required Compliant
4.2 Advisory Compliant

Identifiers 🔗

Rule Category Compliance
5.1 Required Compliant
5.2 Required Compliant
5.3 Required Compliant
5.4 Required Compliant
5.5 Required Compliant
5.6 Required Compliant
5.7 Required Compliant
5.8 Required Compliant
5.9 Advisory Compliant

Types 🔗

Rule Category Compliance
6.1 Required Compliant
6.2 Required Compliant

Literals and Constants 🔗

Rule Category Compliance
7.1 Required Compliant
7.2 Required Compliant
7.3 Required Compliant
7.4 Required Compliant

Declarations and Definitions 🔗

Rule Category Compliance
8.1 Required Compliant
8.2 Required Compliant
8.3 Required Compliant
8.4 Required Compliant
8.5 Required Compliant
8.6 Required Compliant
8.7 Advisory Compliant [1]
8.8 Required Compliant
8.9 Advisory Non-compliant [2]
8.10 Required Compliant
8.11 Advisory Compliant
8.13 Advisory Compliant
8.14 Required Compliant

[1] This rule is not observed for the single header/source amalgamation (the public release). This is because the amalgamation combines all translation units into a single translation unit and does not update linkages in the process. The unamalgamated, MISRA compliant implementation is exclusively available to commercial licensees.

[2] The Unicode data tables are programmatically generated and therefore are not inlined in the functions that depend on them.

Initialization 🔗

Rule Category Compliance
9.1 Mandatory Compliant
9.2 Required Compliant
9.3 Required Compliant
9.4 Required Compliant
9.5 Required Compliant

The Essential Type Modal 🔗

Rule Category Compliance
10.1 Required Compliant [1]
10.2 Required Compliant
10.3 Required Compliant [1]
10.4 Required Compliant [1]
10.5 Advisory Non-compliant [2]
10.6 Required Compliant
10.7 Required Compliant
10.8 Required Compliant

[1] The implementation of Unicorn uses the UINT8_C and UINT16_C macros when declaring constants, however, if your MISRA tool does not recognize these macros as creating unsigned values, then it may report a violation.

[2] The programmatically generated Unicode data tables use the smallest C integer types they can. When returning this data to the user, it may be cast to an enum type.

Pointer Type Conversion 🔗

Rule Category Compliance
11.1 Required Compliant
11.2 Required Compliant
11.3 Required Compliant
11.4 Advisory Compliant
11.5 Advisory Non-compliant [1]
11.6 Required Compliant
11.7 Required Compliant
11.8 Required Compliant
11.9 Required Compliant

[1] In a few select locations Unicorn casts from a void* to a uint8_t*, uint16_t*, or uint32_t*. These casts are performed because Unicorn accepts encoded text as a void* and must internally cast it to an integer pointer with the appropriate storage class. While Unicorn casts are known to be safe via unit testing the caller must ensure they specify the correct encoding form. Specifying the incorrect encoding form will result in a cast to an incorrect storage class resulting in undefined behavior.

Expressions 🔗

Rule Category Compliance
12.1 Advisory Compliant
12.2 Required Compliant
12.3 Advisory Compliant
12.4 Advisory Compliant
12.5 Mandatory Compliant

Side Effects 🔗

Rule Category Compliance
13.1 Required Compliant
13.2 Required Compliant
13.3 Advisory Compliant
13.4 Advisory Compliant
13.5 Required Compliant
13.6 Mandatory Compliant

Control Statement Expressions 🔗

Rule Category Compliance
14.1 Required Compliant
14.2 Required Compliant
14.3 Required Compliant
14.4 Required Compliant

Control Flow 🔗

Rule Category Compliance
15.1 Advisory Compliant
15.2 Required Compliant
15.3 Required Compliant
15.4 Advisory Compliant
15.5 Advisory Compliant
15.6 Required Compliant
15.7 Required Compliant [1]

[1] The unamalgamated implementation of Unicorn is compliant, however, the amalgmation is non-compliant because all comments are removed from it.

Switch Statements 🔗

Rule Category Compliance
16.1 Required Compliant
16.2 Required Compliant
16.3 Required Compliant
16.4 Required Compliant
16.5 Required Compliant
16.6 Required Compliant
16.7 Required Compliant

Functions 🔗

Rule Category Compliance
17.1 Required Compliant
17.2 Required Non-compliant [1]
17.3 Mandatory Compliant (verified via Clang)
17.4 Mandatory Compliant
17.5 Advisory Compliant
17.6 Mandatory Compliant
17.7 Required Compliant
17.8 Advisory Compliant

[1] Recursion is used when processing immutable pregenerated data structures. In these cases the maximum recursion depth is known.

Pointers and Arrays 🔗

Rule Category Compliance
18.1 Required Compliant
18.2 Required Compliant
18.3 Required Compliant
18.4 Advisory Compliant
18.5 Advisory Compliant
18.6 Required Compliant
18.7 Required Compliant
18.8 Required Compliant

Overlapping Storage 🔗

Rule Category Compliance
19.1 Mandatory Compliant
19.2 Advisory Compliant

Preprocessing Directives 🔗

Rule Category Compliance
20.1 Advisory Compliant
20.2 Required Compliant
20.3 Required Compliant
20.4 Required Compliant
20.5 Advisory Compliant
20.7 Required Compliant
20.8 Required Compliant
20.9 Required Compliant
20.10 Advisory Compliant
20.11 Required Compliant
20.12 Required Compliant
20.13 Required Compliant
20.14 Required Compliant

Standard Libraries 🔗

Rule Category Compliance
21.1 Required Compliant
21.2 Required Compliant
21.3 Required Non-compliant [1]
21.4 Required Compliant
21.5 Required Compliant
21.6 Required Compliant
21.7 Required Compliant
21.8 Required Compliant
21.9 Required Compliant
21.10 Required Compliant
21.11 Required Compliant
21.12 Advisory Compliant
21.13 Mandatory Compliant
21.14 Required Compliant
21.15 Required Compliant
21.16 Required Compliant
21.17 Mandatory Compliant
21.18 Mandatory Compliant
21.19 Mandatory Compliant

[1] The realloc and free functions are present but optional.

Resources 🔗

Rule Category Compliance
22.1 Required Compliant
22.2 Mandatory Compliant
21.20 Mandatory Compliant
22.3 Required Compliant
22.4 Mandatory Compliant
22.5 Mandatory Compliant
22.6 Mandatory Compliant
22.7 Required Compliant
22.8 Required Compliant
22.9 Required Compliant
22.10 Required Compliant