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 and its amendments.

Conformance to most MISRA rules is verified with static analysis tools against the unamalgamated source code. Readers are encouraged to run their own static analysis tools against the public, amalgamated source code with the understanding that some false positives might be reported.

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.

Formal documentation:

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
D4.4	Advisory	Compliant
D4.5	Advisory	Compliant
D4.6	Advisory	Compliant
D4.7	Required	Compliant (manually verified)
D4.8	Advisory	Non-compliant [1]
D4.9	Advisory	Compliant [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	Advisory	Compliant
1.3	Required	Compliant
1.4	Required	Compliant
1.5	Required	Compliant

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
2.8	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
6.3	Required	Compliant

Literals and Constants 🔗

Rule	Category	Compliance
7.1	Required	Compliant
7.2	Required	Compliant
7.3	Required	Compliant
7.4	Required	Compliant
7.5	Mandatory	Compliant
7.6	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	Compliant
8.10	Required	Compliant
8.11	Advisory	Compliant
8.12	Required	Compliant
8.13	Advisory	Compliant
8.14	Required	Compliant
8.15	Required	Compliant
8.16	Advisory	Compliant
8.17	Advisory	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.

Initialization 🔗

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

The Essential Type Modal 🔗

Rule	Category	Compliance
10.1	Required	Compliant
10.2	Required	Compliant
10.3	Required	Compliant
10.4	Required	Compliant
10.5	Advisory	Compliant
10.6	Required	Compliant
10.7	Required	Compliant
10.8	Required	Compliant

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
11.10	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
12.6	Required	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
17.9	Mandatory	Compliant
17.10	Required	Compliant
17.11	Advisory	Compliant
17.12	Advisory	Compliant
17.13	Required	Compliant

[1] Recursion is used when processing immutable pregenerated data structures. In these situations, the maximum recursion depth is shallow and 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
18.9	Required	Compliant
18.10	Mandatory	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
20.6	Required	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	Required	Compliant
21.18	Mandatory	Compliant
21.19	Mandatory	Compliant
21.20	Mandatory	Compliant
21.21	Required	Compliant
21.22	Mandatory	Compliant
21.23	Required	Compliant
21.24	Required	Compliant
21.25	Required	Compliant
21.26	Required	Compliant

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

Resources 🔗

Rule	Category	Compliance
22.1	Required	Compliant
22.2	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
22.11	Required	Compliant
22.12	Mandatory	Compliant
22.13	Required	Compliant
22.14	Mandatory	Compliant
22.15	Required	Compliant
22.16	Required	Compliant
22.17	Required	Compliant
22.18	Required	Compliant
22.19	Required	Compliant
22.20	Mandatory	Compliant

Generic Selections 🔗

Rule	Category	Compliance
23.1	Advisory	Compliant
23.2	Required	Compliant
23.3	Advisory	Compliant
23.4	Required	Compliant
23.5	Advisory	Compliant
23.6	Required	Compliant
23.7	Advisory	Compliant
23.8	Required	Compliant

Manual