1.. _coding_guidelines: 2 3Coding Guidelines 4################# 5 6 7Main rules 8********** 9 10The coding guideline rules are based on MISRA-C 2012 and are a **subset** of MISRA-C. 11The subset is listed in the table below with a summary of the rules, its 12severity and the equivalent rules from other standards for reference. 13 14.. note:: 15 16 For existing Zephyr maintainers and collaborators, if you are unable to 17 obtain a copy through your employer, a limited number of copies will be made 18 available through the project. If you need a copy of MISRA-C 2012, please 19 send email to safety@lists.zephyrproject.org and provide details on reason 20 why you can't obtain one through other options and expected contributions 21 once you have one. The safety committee will review all requests. 22 23 24.. list-table:: Main rules 25 :header-rows: 1 26 :widths: 12 45 15 14 12 27 28 * - Zephyr rule 29 - Description 30 - MISRA-C 2012 rule 31 - MISRA-C severity 32 - CERT C reference 33 34 .. _MisraC_Dir_1_1: 35 * - 1 36 - Any implementation-defined behaviour on which the output of the program depends shall be documented and understood 37 - `Dir 1.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_01_01.c>`_ 38 - Required 39 - `MSC09-C <https://wiki.sei.cmu.edu/confluence/display/c/MSC09-C.+Character+encoding%3A+Use+subset+of+ASCII+for+safety>`_ 40 41 .. _MisraC_Dir_2_1: 42 * - 2 43 - All source files shall compile without any compilation errors 44 - `Dir 2.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_02_01.c>`_ 45 - Required 46 - N/A 47 48 .. _MisraC_Dir_3_1: 49 * - 3 50 - All code shall be traceable to documented requirements 51 - `Dir 3.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_03_01.c>`_ 52 - Required 53 - N/A 54 55 .. _MisraC_Dir_4_1: 56 * - 4 57 - Run-time failures shall be minimized 58 - `Dir 4.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_01.c>`_ 59 - Required 60 - N/A 61 62 .. _MisraC_Dir_4_2: 63 * - 5 64 - All usage of assembly language should be documented 65 - `Dir 4.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_02.c>`_ 66 - Advisory 67 - N/A 68 69 .. _MisraC_Dir_4_4: 70 * - 6 71 - Sections of code should not be “commented out” 72 - `Dir 4.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_04.c>`_ 73 - Advisory 74 - `MSC04-C <https://wiki.sei.cmu.edu/confluence/display/c/MSC04-C.+Use+comments+consistently+and+in+a+readable+fashion>`_ 75 76 .. _MisraC_Dir_4_5: 77 * - 7 78 - Identifiers in the same name space with overlapping visibility should be typographically unambiguous 79 - `Dir 4.5 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_05.c>`_ 80 - Advisory 81 - `DCL02-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL02-C.+Use+visually+distinct+identifiers>`_ 82 83 .. _MisraC_Dir_4_6: 84 * - 8 85 - typedefs that indicate size and signedness should be used in place of the basic numerical types 86 - `Dir 4.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_06.c>`_ 87 - Advisory 88 - N/A 89 90 .. _MisraC_Dir_4_7: 91 * - 9 92 - If a function returns error information, then that error information shall be tested 93 - `Dir 4.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_07.c>`_ 94 - Required 95 - N/A 96 97 .. _MisraC_Dir_4_8: 98 * - 10 99 - If a pointer to a structure or union is never dereferenced within a translation unit, then the implementation of the object should be hidden 100 - | `Dir 4.8 example 1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_08_1.c>`_ 101 | `Dir 4.8 example 2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_08_2.c>`_ 102 - Advisory 103 - `DCL12-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL12-C.+Implement+abstract+data+types+using+opaque+types>`_ 104 105 .. _MisraC_Dir_4_9: 106 * - 11 107 - A function should be used in preference to a function-like macro where they are interchangeable 108 - `Dir 4.9 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_09.c>`_ 109 - Advisory 110 - `PRE00-C <https://wiki.sei.cmu.edu/confluence/display/c/PRE00-C.+Prefer+inline+or+static+functions+to+function-like+macros>`_ 111 112 .. _MisraC_Dir_4_10: 113 * - 12 114 - Precautions shall be taken in order to prevent the contents of a header file being included more than once 115 - `Dir 4.10 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_10.c>`_ 116 - Required 117 - `PRE06-C <https://wiki.sei.cmu.edu/confluence/display/c/PRE06-C.+Enclose+header+files+in+an+include+guard>`_ 118 119 .. _MisraC_Dir_4_11: 120 * - 13 121 - The validity of values passed to library functions shall be checked 122 - `Dir 4.11 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_11.c>`_ 123 - Required 124 - N/A 125 126 .. _MisraC_Dir_4_12: 127 * - 14 128 - Dynamic memory allocation shall not be used 129 - `Dir 4.12 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_12.c>`_ 130 - Required 131 - `STR01-C <https://wiki.sei.cmu.edu/confluence/display/c/STR01-C.+Adopt+and+implement+a+consistent+plan+for+managing+strings>`_ 132 133 .. _MisraC_Dir_4_13: 134 * - 15 135 - Functions which are designed to provide operations on a resource should be called in an appropriate sequence 136 - `Dir 4.13 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_13.c>`_ 137 - Advisory 138 - N/A 139 140 .. _MisraC_Dir_4_14: 141 * - 16 142 - The validity of values received from external sources shall be checked 143 - `Dir 4.14 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/D_04_14.c>`_ 144 - Required 145 - N/A 146 147 .. _MisraC_Rule_1_2: 148 * - 17 149 - Language extensions should not be used 150 - `Rule 1.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_01_02.c>`_ 151 - Advisory 152 - `MSC04-C <https://wiki.sei.cmu.edu/confluence/display/c/MSC04-C.+Use+comments+consistently+and+in+a+readable+fashion>`_ 153 154 .. _MisraC_Rule_1_3: 155 * - 18 156 - There shall be no occurrence of undefined or critical unspecified behaviour 157 - `Rule 1.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_01_03.c>`_ 158 - Required 159 - N/A 160 161 .. _MisraC_Rule_2_1: 162 * - 19 163 - A project shall not contain unreachable code 164 - | `Rule 2.1 example 1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_02_01_1.c>`_ 165 | `Rule 2.1 example 2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_02_01_2.c>`_ 166 - Required 167 - `MSC07-C <https://wiki.sei.cmu.edu/confluence/display/c/MSC07-C.+Detect+and+remove+dead+code>`_ 168 169 .. _MisraC_Rule_2_2: 170 * - 20 171 - There shall be no dead code 172 - `Rule 2.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_02_02.c>`_ 173 - Required 174 - `MSC12-C <https://wiki.sei.cmu.edu/confluence/display/c/MSC12-C.+Detect+and+remove+code+that+has+no+effect+or+is+never+executed>`_ 175 176 .. _MisraC_Rule_2_3: 177 * - 21 178 - A project should not contain unused type declarations 179 - `Rule 2.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_02_03.c>`_ 180 - Advisory 181 - N/A 182 183 .. _MisraC_Rule_2_6: 184 * - 22 185 - A function should not contain unused label declarations 186 - `Rule 2.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_02_06.c>`_ 187 - Advisory 188 - N/A 189 190 .. _MisraC_Rule_2_7: 191 * - 23 192 - There should be no unused parameters in functions 193 - `Rule 2.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_02_07.c>`_ 194 - Advisory 195 - N/A 196 197 .. _MisraC_Rule_3_1: 198 * - 24 199 - The character sequences /* and // shall not be used within a comment 200 - `Rule 3.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_03_01.c>`_ 201 - Required 202 - `MSC04-C <https://wiki.sei.cmu.edu/confluence/display/c/MSC04-C.+Use+comments+consistently+and+in+a+readable+fashion>`_ 203 204 .. _MisraC_Rule_3_2: 205 * - 25 206 - Line-splicing shall not be used in // comments 207 - `Rule 3.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_03_02.c>`_ 208 - Required 209 - N/A 210 211 .. _MisraC_Rule_4_1: 212 * - 26 213 - Octal and hexadecimal escape sequences shall be terminated 214 - `Rule 4.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_04_01.c>`_ 215 - Required 216 - `MSC09-C <https://wiki.sei.cmu.edu/confluence/display/c/MSC09-C.+Character+encoding%3A+Use+subset+of+ASCII+for+safety>`_ 217 218 .. _MisraC_Rule_4_2: 219 * - 27 220 - Trigraphs should not be used 221 - `Rule 4.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_04_02.c>`_ 222 - Advisory 223 - `PRE07-C <https://wiki.sei.cmu.edu/confluence/display/c/PRE07-C.+Avoid+using+repeated+question+marks>`_ 224 225 .. _MisraC_Rule_5_1: 226 * - 28 227 - External identifiers shall be distinct 228 - | `Rule 5.1 example 1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_01_1.c>`_ 229 | `Rule 5.1 example 2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_01_2.c>`_ 230 - Required 231 - `DCL23-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL23-C.+Guarantee+that+mutually+visible+identifiers+are+unique>`_ 232 233 .. _MisraC_Rule_5_2: 234 * - 29 235 - Identifiers declared in the same scope and name space shall be distinct 236 - `Rule 5.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_02.c>`_ 237 - Required 238 - `DCL23-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL23-C.+Guarantee+that+mutually+visible+identifiers+are+unique>`_ 239 240 .. _MisraC_Rule_5_3: 241 * - 30 242 - An identifier declared in an inner scope shall not hide an identifier declared in an outer scope 243 - `Rule 5.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_03.c>`_ 244 - Required 245 - `DCL23-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL23-C.+Guarantee+that+mutually+visible+identifiers+are+unique>`_ 246 247 .. _MisraC_Rule_5_4: 248 * - 31 249 - Macro identifiers shall be distinct 250 - `Rule 5.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_04.c>`_ 251 - Required 252 - `DCL23-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL23-C.+Guarantee+that+mutually+visible+identifiers+are+unique>`_ 253 254 .. _MisraC_Rule_5_5: 255 * - 32 256 - Identifiers shall be distinct from macro names 257 - `Rule 5.5 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_05.c>`_ 258 - Required 259 - `DCL23-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL23-C.+Guarantee+that+mutually+visible+identifiers+are+unique>`_ 260 261 .. _MisraC_Rule_5_6: 262 * - 33 263 - A typedef name shall be a unique identifier 264 - `Rule 5.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_06.c>`_ 265 - Required 266 - N/A 267 268 .. _MisraC_Rule_5_7: 269 * - 34 270 - A tag name shall be a unique identifier 271 - `Rule 5.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_07.c>`_ 272 - Required 273 - N/A 274 275 .. _MisraC_Rule_5_8: 276 * - 35 277 - Identifiers that define objects or functions with external linkage shall be unique 278 - | `Rule 5.8 example 1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_08_1.c>`_ 279 | `Rule 5.8 example 2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_08_2.c>`_ 280 - Required 281 - N/A 282 283 .. _MisraC_Rule_5_9: 284 * - 36 285 - Identifiers that define objects or functions with internal linkage should be unique 286 - | `Rule 5.9 example 1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_09_1.c>`_ 287 | `Rule 5.9 example 2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_09_2.c>`_ 288 - Advisory 289 - N/A 290 291 .. _MisraC_Rule_6_1: 292 * - 37 293 - Bit-fields shall only be declared with an appropriate type 294 - `Rule 6.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_06_01.c>`_ 295 - Required 296 - `INT14-C <https://wiki.sei.cmu.edu/confluence/display/c/INT14-C.+Avoid+performing+bitwise+and+arithmetic+operations+on+the+same+data>`_ 297 298 .. _MisraC_Rule_6_2: 299 * - 38 300 - Single-bit named bit fields shall not be of a signed type 301 - `Rule 6.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_06_02.c>`_ 302 - Required 303 - `INT14-C <https://wiki.sei.cmu.edu/confluence/display/c/INT14-C.+Avoid+performing+bitwise+and+arithmetic+operations+on+the+same+data>`_ 304 305 .. _MisraC_Rule_7_1: 306 * - 39 307 - Octal constants shall not be used 308 - `Rule 7.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_07_01.c>`_ 309 - Required 310 - `DCL18-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL18-C.+Do+not+begin+integer+constants+with+0+when+specifying+a+decimal+value>`_ 311 312 .. _MisraC_Rule_7_2: 313 * - 40 314 - A u or U suffix shall be applied to all integer constants that are represented in an unsigned type 315 - `Rule 7.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_07_02.c>`_ 316 - Required 317 - N/A 318 319 .. _MisraC_Rule_7_3: 320 * - 41 321 - The lowercase character l shall not be used in a literal suffix 322 - `Rule 7.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_07_03.c>`_ 323 - Required 324 - `DCL16-C <https://wiki.sei.cmu.edu/confluence/pages/viewpage.action?pageId=87152241>`_ 325 326 .. _MisraC_Rule_7_4: 327 * - 42 328 - A string literal shall not be assigned to an object unless the objects type is pointer to const-qualified char 329 - `Rule 7.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_07_04.c>`_ 330 - Required 331 - N/A 332 333 .. _MisraC_Rule_8_1: 334 * - 43 335 - Types shall be explicitly specified 336 - `Rule 8.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_01.c>`_ 337 - Required 338 - N/A 339 340 .. _MisraC_Rule_8_2: 341 * - 44 342 - Function types shall be in prototype form with named parameters 343 - `Rule 8.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_02.c>`_ 344 - Required 345 - `DCL20-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL20-C.+Explicitly+specify+void+when+a+function+accepts+no+arguments>`_ 346 347 .. _MisraC_Rule_8_3: 348 * - 45 349 - All declarations of an object or function shall use the same names and type qualifiers 350 - `Rule 8.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_03.c>`_ 351 - Required 352 - N/A 353 354 .. _MisraC_Rule_8_4: 355 * - 46 356 - A compatible declaration shall be visible when an object or function with external linkage is defined 357 - `Rule 8.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_04.c>`_ 358 - Required 359 - N/A 360 361 .. _MisraC_Rule_8_5: 362 * - 47 363 - An external object or function shall be declared once in one and only one file 364 - | `Rule 8.5 example 1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_05_1.c>`_ 365 | `Rule 8.5 example 2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_05_2.c>`_ 366 - Required 367 - N/A 368 369 .. _MisraC_Rule_8_6: 370 * - 48 371 - An identifier with external linkage shall have exactly one external definition 372 - | `Rule 8.6 example 1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_06_1.c>`_ 373 | `Rule 8.6 example 2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_06_2.c>`_ 374 - Required 375 - N/A 376 377 .. _MisraC_Rule_8_8: 378 * - 49 379 - The static storage class specifier shall be used in all declarations of objects and functions that have internal linkage 380 - `Rule 8.8 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_08.c>`_ 381 - Required 382 - `DCL15-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL15-C.+Declare+file-scope+objects+or+functions+that+do+not+need+external+linkage+as+static>`_ 383 384 .. _MisraC_Rule_8_9: 385 * - 50 386 - An object should be defined at block scope if its identifier only appears in a single function 387 - `Rule 8.9 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_09.c>`_ 388 - Advisory 389 - `DCL19-C <https://wiki.sei.cmu.edu/confluence/display/c/DCL19-C.+Minimize+the+scope+of+variables+and+functions>`_ 390 391 .. _MisraC_Rule_8_10: 392 * - 51 393 - An inline function shall be declared with the static storage class 394 - `Rule 8.10 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_10.c>`_ 395 - Required 396 - N/A 397 398 .. _MisraC_Rule_8_12: 399 * - 52 400 - Within an enumerator list, the value of an implicitly-specified enumeration constant shall be unique 401 - `Rule 8.12 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_12.c>`_ 402 - Required 403 - `INT09-C <https://wiki.sei.cmu.edu/confluence/display/c/INT09-C.+Ensure+enumeration+constants+map+to+unique+values>`_ 404 405 .. _MisraC_Rule_8_14: 406 * - 53 407 - The restrict type qualifier shall not be used 408 - `Rule 8.14 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_08_14.c>`_ 409 - Required 410 - N/A 411 412 .. _MisraC_Rule_9_1: 413 * - 54 414 - The value of an object with automatic storage duration shall not be read before it has been set 415 - `Rule 9.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_09_01.c>`_ 416 - Mandatory 417 - N/A 418 419 .. _MisraC_Rule_9_2: 420 * - 55 421 - The initializer for an aggregate or union shall be enclosed in braces 422 - `Rule 9.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_09_02.c>`_ 423 - Required 424 - N/A 425 426 .. _MisraC_Rule_9_3: 427 * - 56 428 - Arrays shall not be partially initialized 429 - `Rule 9.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_09_03.c>`_ 430 - Required 431 - N/A 432 433 .. _MisraC_Rule_9_4: 434 * - 57 435 - An element of an object shall not be initialized more than once 436 - `Rule 9.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_09_04.c>`_ 437 - Required 438 - N/A 439 440 .. _MisraC_Rule_9_5: 441 * - 58 442 - Where designated initializers are used to initialize an array object the size of the array shall be specified explicitly 443 - `Rule 9.5 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_09_05.c>`_ 444 - Required 445 - N/A 446 447 .. _MisraC_Rule_10_1: 448 * - 59 449 - Operands shall not be of an inappropriate essential type 450 - `Rule 10.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_01.c>`_ 451 - Required 452 - `STR04-C <https://wiki.sei.cmu.edu/confluence/display/c/STR04-C.+Use+plain+char+for+characters+in+the+basic+character+set>`_ 453 454 .. _MisraC_Rule_10_2: 455 * - 60 456 - Expressions of essentially character type shall not be used inappropriately in addition and subtraction operations 457 - `Rule 10.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_02.c>`_ 458 - Required 459 - `STR04-C <https://wiki.sei.cmu.edu/confluence/display/c/STR04-C.+Use+plain+char+for+characters+in+the+basic+character+set>`_ 460 461 .. _MisraC_Rule_10_3: 462 * - 61 463 - The value of an expression shall not be assigned to an object with a narrower essential type or of a different essential type category 464 - `Rule 10.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_03.c>`_ 465 - Required 466 - `STR04-C <https://wiki.sei.cmu.edu/confluence/display/c/STR04-C.+Use+plain+char+for+characters+in+the+basic+character+set>`_ 467 468 .. _MisraC_Rule_10_4: 469 * - 62 470 - Both operands of an operator in which the usual arithmetic conversions are performed shall have the same essential type category 471 - `Rule 10.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_04.c>`_ 472 - Required 473 - `STR04-C <https://wiki.sei.cmu.edu/confluence/display/c/STR04-C.+Use+plain+char+for+characters+in+the+basic+character+set>`_ 474 475 .. _MisraC_Rule_10_5: 476 * - 63 477 - The value of an expression should not be cast to an inappropriate essential type 478 - `Rule 10.5 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_05.c>`_ 479 - Advisory 480 - N/A 481 482 .. _MisraC_Rule_10_6: 483 * - 64 484 - The value of a composite expression shall not be assigned to an object with wider essential type 485 - `Rule 10.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_06.c>`_ 486 - Required 487 - `INT02-C <https://wiki.sei.cmu.edu/confluence/display/c/INT02-C.+Understand+integer+conversion+rules>`_ 488 489 .. _MisraC_Rule_10_7: 490 * - 65 491 - If a composite expression is used as one operand of an operator in which the usual arithmetic conversions are performed then the other operand shall not have wider essential type 492 - `Rule 10.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_07.c>`_ 493 - Required 494 - `INT02-C <https://wiki.sei.cmu.edu/confluence/display/c/INT02-C.+Understand+integer+conversion+rules>`_ 495 496 .. _MisraC_Rule_10_8: 497 * - 66 498 - The value of a composite expression shall not be cast to a different essential type category or a wider essential type 499 - `Rule 10.8 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_08.c>`_ 500 - Required 501 - `INT02-C <https://wiki.sei.cmu.edu/confluence/display/c/INT02-C.+Understand+integer+conversion+rules>`_ 502 503 .. _MisraC_Rule_11_2: 504 * - 67 505 - Conversions shall not be performed between a pointer to an incomplete type and any other type 506 - `Rule 11.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_11_02.c>`_ 507 - Required 508 - N/A 509 510 .. _MisraC_Rule_11_6: 511 * - 68 512 - A cast shall not be performed between pointer to void and an arithmetic type 513 - `Rule 11.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_11_06.c>`_ 514 - Required 515 - N/A 516 517 .. _MisraC_Rule_11_7: 518 * - 69 519 - A cast shall not be performed between pointer to object and a noninteger arithmetic type 520 - `Rule 11.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_11_07.c>`_ 521 - Required 522 - N/A 523 524 .. _MisraC_Rule_11_8: 525 * - 70 526 - A cast shall not remove any const or volatile qualification from the type pointed to by a pointer 527 - `Rule 11.8 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_11_08.c>`_ 528 - Required 529 - `EXP05-C <https://wiki.sei.cmu.edu/confluence/display/c/EXP05-C.+Do+not+cast+away+a+const+qualification>`_ 530 531 .. _MisraC_Rule_11_9: 532 * - 71 533 - The macro NULL shall be the only permitted form of integer null pointer constant 534 - `Rule 11.9 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_11_09.c>`_ 535 - Required 536 - N/A 537 538 .. _MisraC_Rule_12_1: 539 * - 72 540 - The precedence of operators within expressions should be made explicit 541 - `Rule 12.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_12_01.c>`_ 542 - Advisory 543 - `EXP00-C <https://wiki.sei.cmu.edu/confluence/display/c/EXP00-C.+Use+parentheses+for+precedence+of+operation>`_ 544 545 .. _MisraC_Rule_12_2: 546 * - 73 547 - The right hand operand of a shift operator shall lie in the range zero to one less than the width in bits of the essential type of the left hand operand 548 - `Rule 12.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_12_02.c>`_ 549 - Required 550 - N/A 551 552 .. _MisraC_Rule_12_4: 553 * - 74 554 - Evaluation of constant expressions should not lead to unsigned integer wrap-around 555 - `Rule 12.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_12_04.c>`_ 556 - Advisory 557 - N/A 558 559 .. _MisraC_Rule_12_5: 560 * - 75 561 - The sizeof operator shall not have an operand which is a function parameter declared as “array of type” 562 - `Rule 12.5 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_12_05.c>`_ 563 - Mandatory 564 - N/A 565 566 .. _MisraC_Rule_13_1: 567 * - 76 568 - Initializer lists shall not contain persistent side effects 569 - | `Rule 13.1 example 1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_13_01_1.c>`_ 570 | `Rule 13.1 example 2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_13_01_2.c>`_ 571 - Required 572 - N/A 573 574 .. _MisraC_Rule_13_2: 575 * - 77 576 - The value of an expression and its persistent side effects shall be the same under all permitted evaluation orders 577 - `Rule 13.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_13_02.c>`_ 578 - Required 579 - N/A 580 581 .. _MisraC_Rule_13_3: 582 * - 78 583 - A full expression containing an increment (++) or decrement (--) operator should have no other potential side effects other than that caused by the increment or decrement operator 584 - `Rule 13.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_13_03.c>`_ 585 - Advisory 586 - N/A 587 588 .. _MisraC_Rule_13_4: 589 * - 79 590 - The result of an assignment operator should not be used 591 - `Rule 13.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_13_04.c>`_ 592 - Advisory 593 - N/A 594 595 .. _MisraC_Rule_13_5: 596 * - 80 597 - The right hand operand of a logical && or || operator shall not contain persistent side effects 598 - | `Rule 13.5 example 1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_13_05_1.c>`_ 599 | `Rule 13.5 example 2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_13_05_2.c>`_ 600 - Required 601 - `EXP10-C <https://wiki.sei.cmu.edu/confluence/display/c/EXP10-C.+Do+not+depend+on+the+order+of+evaluation+of+subexpressions+or+the+order+in+which+side+effects+take+place>`_ 602 603 .. _MisraC_Rule_13_6: 604 * - 81 605 - The operand of the sizeof operator shall not contain any expression which has potential side effects 606 - `Rule 13.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_13_06.c>`_ 607 - Mandatory 608 - N/A 609 610 .. _MisraC_Rule_14_1: 611 * - 82 612 - A loop counter shall not have essentially floating type 613 - `Rule 14.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_14_01.c>`_ 614 - Required 615 - N/A 616 617 .. _MisraC_Rule_14_2: 618 * - 83 619 - A for loop shall be well-formed 620 - `Rule 14.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_14_02.c>`_ 621 - Required 622 - N/A 623 624 .. _MisraC_Rule_14_3: 625 * - 84 626 - Controlling expressions shall not be invariant 627 - `Rule 14.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_14_03.c>`_ 628 - Required 629 - N/A 630 631 .. _MisraC_Rule_14_4: 632 * - 85 633 - The controlling expression of an if statement and the controlling expression of an iteration-statement shall have essentially Boolean type 634 - `Rule 14.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_14_04.c>`_ 635 - Required 636 - N/A 637 638 .. _MisraC_Rule_15_2: 639 * - 86 640 - The goto statement shall jump to a label declared later in the same function 641 - `Rule 15.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_15_02.c>`_ 642 - Required 643 - N/A 644 645 .. _MisraC_Rule_15_3: 646 * - 87 647 - Any label referenced by a goto statement shall be declared in the same block, or in any block enclosing the goto statement 648 - `Rule 15.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_15_03.c>`_ 649 - Required 650 - N/A 651 652 .. _MisraC_Rule_15_6: 653 * - 88 654 - The body of an iteration-statement or a selection-statement shall be a compound-statement 655 - `Rule 15.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_15_06.c>`_ 656 - Required 657 - `EXP19-C <https://wiki.sei.cmu.edu/confluence/display/c/EXP19-C.+Use+braces+for+the+body+of+an+if%2C+for%2C+or+while+statement>`_ 658 659 .. _MisraC_Rule_15_7: 660 * - 89 661 - All if else if constructs shall be terminated with an else statement 662 - `Rule 15.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_15_07.c>`_ 663 - Required 664 - N/A 665 666 .. _MisraC_Rule_16_1: 667 * - 90 668 - All switch statements shall be well-formed 669 - `Rule 16.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_16_01.c>`_ 670 - Required 671 - N/A 672 673 .. _MisraC_Rule_16_2: 674 * - 91 675 - A switch label shall only be used when the most closely-enclosing compound statement is the body of a switch statement 676 - `Rule 16.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_16_02.c>`_ 677 - Required 678 - `MSC20-C <https://wiki.sei.cmu.edu/confluence/display/c/MSC20-C.+Do+not+use+a+switch+statement+to+transfer+control+into+a+complex+block>`_ 679 680 .. _MisraC_Rule_16_3: 681 * - 92 682 - An unconditional break statement shall terminate every switch-clause 683 - `Rule 16.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_16_03.c>`_ 684 - Required 685 - N/A 686 687 .. _MisraC_Rule_16_4: 688 * - 93 689 - Every switch statement shall have a default label 690 - `Rule 16.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_16_04.c>`_ 691 - Required 692 - N/A 693 694 .. _MisraC_Rule_16_5: 695 * - 94 696 - A default label shall appear as either the first or the last switch label of a switch statement 697 - `Rule 16.5 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_16_05.c>`_ 698 - Required 699 - N/A 700 701 .. _MisraC_Rule_16_6: 702 * - 95 703 - Every switch statement shall have at least two switch-clauses 704 - `Rule 16.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_16_06.c>`_ 705 - Required 706 - N/A 707 708 .. _MisraC_Rule_16_7: 709 * - 96 710 - A switch-expression shall not have essentially Boolean type 711 - `Rule 16.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_16_07.c>`_ 712 - Required 713 - N/A 714 715 .. _MisraC_Rule_17_1: 716 * - 97 717 - The features of <stdarg.h> shall not be used 718 - `Rule 17.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_17_01.c>`_ 719 - Required 720 - `ERR00-C <https://wiki.sei.cmu.edu/confluence/display/c/ERR00-C.+Adopt+and+implement+a+consistent+and+comprehensive+error-handling+policy>`_ 721 722 .. _MisraC_Rule_17_2: 723 * - 98 724 - Functions shall not call themselves, either directly or indirectly 725 - `Rule 17.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_17_02.c>`_ 726 - Required 727 - `MEM05-C <https://wiki.sei.cmu.edu/confluence/display/c/MEM05-C.+Avoid+large+stack+allocations>`_ 728 729 .. _MisraC_Rule_17_3: 730 * - 99 731 - A function shall not be declared implicitly 732 - `Rule 17.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_17_03.c>`_ 733 - Mandatory 734 - N/A 735 736 .. _MisraC_Rule_17_4: 737 * - 100 738 - All exit paths from a function with non-void return type shall have an explicit return statement with an expression 739 - `Rule 17.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_17_04.c>`_ 740 - Mandatory 741 - N/A 742 743 .. _MisraC_Rule_17_5: 744 * - 101 745 - The function argument corresponding to a parameter declared to have an array type shall have an appropriate number of elements 746 - `Rule 17.5 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_17_05.c>`_ 747 - Advisory 748 - N/A 749 750 .. _MisraC_Rule_17_6: 751 * - 102 752 - The declaration of an array parameter shall not contain the static keyword between the [ ] 753 - `Rule 17.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_17_06.c>`_ 754 - Mandatory 755 - N/A 756 757 .. _MisraC_Rule_17_7: 758 * - 103 759 - The value returned by a function having non-void return type shall be used 760 - `Rule 17.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_17_07.c>`_ 761 - Required 762 - N/A 763 764 .. _MisraC_Rule_18_1: 765 * - 104 766 - A pointer resulting from arithmetic on a pointer operand shall address an element of the same array as that pointer operand 767 - `Rule 18.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_18_01.c>`_ 768 - Required 769 - `EXP08-C <https://wiki.sei.cmu.edu/confluence/display/c/EXP08-C.+Ensure+pointer+arithmetic+is+used+correctly>`_ 770 771 .. _MisraC_Rule_18_2: 772 * - 105 773 - Subtraction between pointers shall only be applied to pointers that address elements of the same array 774 - `Rule 18.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_18_02.c>`_ 775 - Required 776 - `EXP08-C <https://wiki.sei.cmu.edu/confluence/display/c/EXP08-C.+Ensure+pointer+arithmetic+is+used+correctly>`_ 777 778 .. _MisraC_Rule_18_3: 779 * - 106 780 - The relational operators >, >=, < and <= shall not be applied to objects of pointer type except where they point into the same object 781 - `Rule 18.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_18_03.c>`_ 782 - Required 783 - `EXP08-C <https://wiki.sei.cmu.edu/confluence/display/c/EXP08-C.+Ensure+pointer+arithmetic+is+used+correctly>`_ 784 785 .. _MisraC_Rule_18_5: 786 * - 107 787 - Declarations should contain no more than two levels of pointer nesting 788 - `Rule 18.5 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_18_05.c>`_ 789 - Advisory 790 - N/A 791 792 .. _MisraC_Rule_18_6: 793 * - 108 794 - The address of an object with automatic storage shall not be copied to another object that persists after the first object has ceased to exist 795 - | `Rule 18.6 example 1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_18_06_1.c>`_ 796 | `Rule 18.6 example 2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_18_06_2.c>`_ 797 - Required 798 - N/A 799 800 .. _MisraC_Rule_18_8: 801 * - 109 802 - Variable-length array types shall not be used 803 - `Rule 18.8 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_18_08.c>`_ 804 - Required 805 - N/A 806 807 .. _MisraC_Rule_19_1: 808 * - 110 809 - An object shall not be assigned or copied to an overlapping object 810 - `Rule 19.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_19_01.c>`_ 811 - Mandatory 812 - N/A 813 814 .. _MisraC_Rule_20_2: 815 * - 111 816 - The ', or \ characters and the /* or // character sequences shall not occur in a header file name" 817 - `Rule 20.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_02.c>`_ 818 - Required 819 - N/A 820 821 .. _MisraC_Rule_20_3: 822 * - 112 823 - The #include directive shall be followed by either a <filename> or "filename" sequence 824 - `Rule 20.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_03.c>`_ 825 - Required 826 - N/A 827 828 .. _MisraC_Rule_20_4: 829 * - 113 830 - A macro shall not be defined with the same name as a keyword 831 - `Rule 20.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_04.c>`_ 832 - Required 833 - N/A 834 835 .. _MisraC_Rule_20_7: 836 * - 114 837 - Expressions resulting from the expansion of macro parameters shall be enclosed in parentheses 838 - `Rule 20.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_07.c>`_ 839 - Required 840 - `PRE01-C <https://wiki.sei.cmu.edu/confluence/display/c/PRE01-C.+Use+parentheses+within+macros+around+parameter+names>`_ 841 842 .. _MisraC_Rule_20_8: 843 * - 115 844 - The controlling expression of a #if or #elif preprocessing directive shall evaluate to 0 or 1 845 - `Rule 20.8 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_08.c>`_ 846 - Required 847 - N/A 848 849 .. _MisraC_Rule_20_9: 850 * - 116 851 - All identifiers used in the controlling expression of #if or #elif preprocessing directives shall be #defined before evaluation 852 - `Rule 20.9 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_09.c>`_ 853 - Required 854 - N/A 855 856 .. _MisraC_Rule_20_11: 857 * - 117 858 - A macro parameter immediately following a # operator shall not immediately be followed by a ## operator 859 - `Rule 20.11 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_11.c>`_ 860 - Required 861 - N/A 862 863 .. _MisraC_Rule_20_12: 864 * - 118 865 - A macro parameter used as an operand to the # or ## operators, which is itself subject to further macro replacement, shall only be used as an operand to these operators 866 - `Rule 20.12 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_12.c>`_ 867 - Required 868 - N/A 869 870 .. _MisraC_Rule_20_13: 871 * - 119 872 - A line whose first token is # shall be a valid preprocessing directive 873 - `Rule 20.13 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_13.c>`_ 874 - Required 875 - N/A 876 877 .. _MisraC_Rule_20_14: 878 * - 120 879 - All #else, #elif and #endif preprocessor directives shall reside in the same file as the #if, #ifdef or #ifndef directive to which they are related 880 - `Rule 20.14 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_20_14.c>`_ 881 - Required 882 - N/A 883 884 .. _MisraC_Rule_21_1: 885 * - 121 886 - #define and #undef shall not be used on a reserved identifier or reserved macro name 887 - `Rule 21.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_01.c>`_ 888 - Required 889 - N/A 890 891 .. _MisraC_Rule_21_2: 892 * - 122 893 - A reserved identifier or macro name shall not be declared 894 - `Rule 21.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_02.c>`_ 895 - Required 896 - N/A 897 898 .. _MisraC_Rule_21_3: 899 * - 123 900 - The memory allocation and deallocation functions of <stdlib.h> shall not be used 901 - `Rule 21.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_03.c>`_ 902 - Required 903 - `MSC24-C <https://wiki.sei.cmu.edu/confluence/display/c/MSC24-C.+Do+not+use+deprecated+or+obsolescent+functions>`_ 904 905 .. _MisraC_Rule_21_4: 906 * - 124 907 - The standard header file <setjmp.h> shall not be used 908 - `Rule 21.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_04.c>`_ 909 - Required 910 - N/A 911 912 .. _MisraC_Rule_21_6: 913 * - 125 914 - The Standard Library input/output functions shall not be used 915 - `Rule 21.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_06.c>`_ 916 - Required 917 - N/A 918 919 .. _MisraC_Rule_21_7: 920 * - 126 921 - The atof, atoi, atol and atoll functions of <stdlib.h> shall not be used 922 - `Rule 21.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_07.c>`_ 923 - Required 924 - N/A 925 926 .. _MisraC_Rule_21_9: 927 * - 127 928 - The library functions bsearch and qsort of <stdlib.h> shall not be used 929 - `Rule 21.9 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_09.c>`_ 930 - Required 931 - N/A 932 933 .. _MisraC_Rule_21_11: 934 * - 128 935 - The standard header file <tgmath.h> shall not be used 936 - `Rule 21.11 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_11.c>`_ 937 - Required 938 - N/A 939 940 .. _MisraC_Rule_21_12: 941 * - 129 942 - The exception handling features of <fenv.h> should not be used 943 - `Rule 21.12 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_12.c>`_ 944 - Advisory 945 - N/A 946 947 .. _MisraC_Rule_21_13: 948 * - 130 949 - Any value passed to a function in <ctype.h> shall be representable as an unsigned char or be the value EO 950 - `Rule 21.13 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_13.c>`_ 951 - Mandatory 952 - N/A 953 954 .. _MisraC_Rule_21_14: 955 * - 131 956 - The Standard Library function memcmp shall not be used to compare null terminated strings 957 - `Rule 21.14 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_14.c>`_ 958 - Required 959 - N/A 960 961 .. _MisraC_Rule_21_15: 962 * - 132 963 - The pointer arguments to the Standard Library functions memcpy, memmove and memcmp shall be pointers to qualified or unqualified versions of compatible types 964 - `Rule 21.15 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_15.c>`_ 965 - Required 966 - N/A 967 968 .. _MisraC_Rule_21_16: 969 * - 133 970 - The pointer arguments to the Standard Library function memcmp shall point to either a pointer type, an essentially signed type, an essentially unsigned type, an essentially Boolean type or an essentially enum type 971 - `Rule 21.16 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_16.c>`_ 972 - Required 973 - N/A 974 975 .. _MisraC_Rule_21_17: 976 * - 134 977 - Use of the string handling functions from <string.h> shall not result in accesses beyond the bounds of the objects referenced by their pointer parameters 978 - `Rule 21.17 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_17.c>`_ 979 - Mandatory 980 - N/A 981 982 .. _MisraC_Rule_21_18: 983 * - 135 984 - The size_t argument passed to any function in <string.h> shall have an appropriate value 985 - `Rule 21.18 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_18.c>`_ 986 - Mandatory 987 - N/A 988 989 .. _MisraC_Rule_21_19: 990 * - 136 991 - The pointers returned by the Standard Library functions localeconv, getenv, setlocale or, strerror shall only be used as if they have pointer to const-qualified type 992 - `Rule 21.19 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_19.c>`_ 993 - Mandatory 994 - N/A 995 996 .. _MisraC_Rule_21_20: 997 * - 137 998 - The pointer returned by the Standard Library functions asctime, ctime, gmtime, localtime, localeconv, getenv, setlocale or strerror shall not be used following a subsequent call to the same function 999 - `Rule 21.20 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_21_20.c>`_ 1000 - Mandatory 1001 - N/A 1002 1003 .. _MisraC_Rule_22_1: 1004 * - 138 1005 - All resources obtained dynamically by means of Standard Library functions shall be explicitly released 1006 - `Rule 22.1 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_01.c>`_ 1007 - Required 1008 - N/A 1009 1010 .. _MisraC_Rule_22_2: 1011 * - 139 1012 - A block of memory shall only be freed if it was allocated by means of a Standard Library function 1013 - `Rule 22.2 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_02.c>`_ 1014 - Mandatory 1015 - N/A 1016 1017 .. _MisraC_Rule_22_3: 1018 * - 140 1019 - The same file shall not be open for read and write access at the same time on different streams 1020 - `Rule 22.3 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_03.c>`_ 1021 - Required 1022 - N/A 1023 1024 .. _MisraC_Rule_22_4: 1025 * - 141 1026 - There shall be no attempt to write to a stream which has been opened as read-only 1027 - `Rule 22.4 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_04.c>`_ 1028 - Mandatory 1029 - N/A 1030 1031 .. _MisraC_Rule_22_5: 1032 * - 142 1033 - A pointer to a FILE object shall not be dereferenced 1034 - `Rule 22.5 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_05.c>`_ 1035 - Mandatory 1036 - N/A 1037 1038 .. _MisraC_Rule_22_6: 1039 * - 143 1040 - The value of a pointer to a FILE shall not be used after the associated stream has been closed 1041 - `Rule 22.6 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_06.c>`_ 1042 - Mandatory 1043 - N/A 1044 1045 .. _MisraC_Rule_22_7: 1046 * - 144 1047 - The macro EOF shall only be compared with the unmodified return value from any Standard Library function capable of returning EOF 1048 - `Rule 22.7 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_07.c>`_ 1049 - Required 1050 - N/A 1051 1052 .. _MisraC_Rule_22_8: 1053 * - 145 1054 - The value of errno shall be set to zero prior to a call to an errno-setting-function 1055 - `Rule 22.8 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_08.c>`_ 1056 - Required 1057 - N/A 1058 1059 .. _MisraC_Rule_22_9: 1060 * - 146 1061 - The value of errno shall be tested against zero after calling an errno-setting-function 1062 - `Rule 22.9 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_09.c>`_ 1063 - Required 1064 - N/A 1065 1066 .. _MisraC_Rule_22_10: 1067 * - 147 1068 - The value of errno shall only be tested when the last function to be called was an errno-setting-function 1069 - `Rule 22.10 <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_22_10.c>`_ 1070 - Required 1071 - N/A 1072 1073Additional rules 1074**************** 1075 1076Rule A.1: Conditional Compilation 1077================================= 1078Severity 1079 Required 1080 1081Description 1082 Do not conditionally compile function declarations in header files. Do not 1083 conditionally compile structure declarations in header files. You may 1084 conditionally exclude fields within structure definitions to avoid wasting 1085 memory when the feature they support is not enabled. 1086 1087Rationale 1088 Excluding declarations from the header based on compile-time options may prevent 1089 their documentation from being generated. Their absence also prevents use of 1090 ``if (IS_ENABLED(CONFIG_FOO)) {}`` as an alternative to preprocessor 1091 conditionals when the code path should change based on the selected options. 1092 1093.. _coding_guideline_inclusive_language: 1094 1095Rule A.2: Inclusive Language 1096============================ 1097Severity 1098 Required 1099 1100Description 1101 Do not introduce new usage of offensive terms listed below. This rule applies 1102 but is not limited to source code, comments, documentation, and branch names. 1103 Replacement terms may vary by area or subsystem, but should aim to follow 1104 updated industry standards when possible. 1105 1106 Exceptions are allowed for maintaining existing implementations or adding new 1107 implementations of industry standard specifications governed externally to the 1108 Zephyr Project. 1109 1110 Existing usage is recommended to change as soon as updated industry standard 1111 specifications become available or new terms are publicly announced by the 1112 governing body, or immediately if no specifications apply. 1113 1114 .. list-table:: 1115 :header-rows: 1 1116 1117 * - Offensive Terms 1118 - Recommended Replacements 1119 1120 * - ``{master,leader} / slave`` 1121 - - ``{primary,main} / {secondary,replica}`` 1122 - ``{initiator,requester} / {target,responder}`` 1123 - ``{controller,host} / {device,worker,proxy,target}`` 1124 - ``director / performer`` 1125 - ``central / peripheral`` 1126 1127 * - ``blacklist / whitelist`` 1128 - * ``denylist / allowlist`` 1129 * ``blocklist / allowlist`` 1130 * ``rejectlist / acceptlist`` 1131 1132 * - ``grandfather policy`` 1133 - * ``legacy`` 1134 1135 * - ``sanity`` 1136 - * ``coherence`` 1137 * ``confidence`` 1138 1139Rationale 1140 Offensive terms do not create an inclusive community environment and therefore 1141 violate the Zephyr Project `Code of Conduct`_. This coding rule was inspired by 1142 a similar rule in `Linux`_. 1143 1144 .. _Code of Conduct: https://github.com/zephyrproject-rtos/zephyr/blob/main/CODE_OF_CONDUCT.md 1145 .. _Linux: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=49decddd39e5f6132ccd7d9fdc3d7c470b0061bb 1146 1147Status 1148 Related GitHub Issues and Pull Requests are tagged with the `Inclusive Language Label`_. 1149 1150 .. list-table:: 1151 :header-rows: 1 1152 1153 * - Area 1154 - Selected Replacements 1155 - Status 1156 1157 * - :ref:`Bluetooth <bluetooth_api>` 1158 - See `Bluetooth Appropriate Language Mapping Tables`_ 1159 - 1160 1161 * - CAN 1162 - This `CAN in Automation Inclusive Language news post`_ has a list of general 1163 recommendations. See `CAN in Automation Inclusive Language`_ for terms to 1164 be used in specification document updates. 1165 - 1166 1167 * - eSPI 1168 - * ``master / slave`` => ``controller / target`` 1169 - Refer to `eSPI Specification`_ for new terminology 1170 1171 * - gPTP 1172 - * ``master / slave`` => TBD 1173 - 1174 1175 * - :ref:`i2c_api` 1176 - * ``master / slave`` => TBD 1177 - NXP publishes the `I2C Specification`_ and has selected ``controller / 1178 target`` as replacement terms, but the timing to publish an announcement 1179 or new specification is TBD. Zephyr will update I2C when replacement 1180 terminology is confirmed by a public announcement or updated 1181 specification. 1182 1183 See :github:`Zephyr issue 27033 <27033>`. 1184 1185 * - :ref:`i2s_api` 1186 - * ``master / slave`` => TBD 1187 - 1188 1189 * - SMP/AMP 1190 - * ``master / slave`` => TBD 1191 - 1192 1193 * - :ref:`spi_api` 1194 - * ``master / slave`` => ``controller / peripheral`` 1195 * ``MOSI / MISO / SS`` => ``SDO / SDI / CS`` 1196 - The Open Source Hardware Association has selected these replacement 1197 terms. See `OSHWA Resolution to Redefine SPI Signal Names`_ 1198 1199 * - :ref:`twister_script` 1200 - * ``platform_whitelist`` => ``platform_allow`` 1201 * ``sanitycheck`` => ``twister`` 1202 - 1203 1204 .. _Inclusive Language Label: https://github.com/zephyrproject-rtos/zephyr/issues?q=label%3A%22Inclusive+Language%22 1205 .. _I2C Specification: https://www.nxp.com/docs/en/user-guide/UM10204.pdf 1206 .. _Bluetooth Appropriate Language Mapping Tables: https://specificationrefs.bluetooth.com/language-mapping/Appropriate_Language_Mapping_Table.pdf 1207 .. _OSHWA Resolution to Redefine SPI Signal Names: https://www.oshwa.org/a-resolution-to-redefine-spi-signal-names/ 1208 .. _CAN in Automation Inclusive Language news post: https://www.can-cia.org/news/archive/view/?tx_news_pi1%5Bnews%5D=699&tx_news_pi1%5Bday%5D=6&tx_news_pi1%5Bmonth%5D=12&tx_news_pi1%5Byear%5D=2020&cHash=784e79eb438141179386cf7c29ed9438 1209 .. _CAN in Automation Inclusive Language: https://can-newsletter.org/canopen/categories/ 1210 .. _eSPI Specification: https://downloadmirror.intel.com/27055/327432%20espi_base_specification%20R1-5.pdf 1211 1212 1213.. _coding_guideline_libc_usage_restrictions_in_zephyr_kernel: 1214 1215Rule A.3: Macro name collisions 1216=============================== 1217Severity 1218 Required 1219 1220Description 1221 Macros with commonly used names such as ``MIN``, ``MAX``, ``ARRAY_SIZE``, must not be modified or 1222 protected to avoid name collisions with other implementations. In particular, they must not be 1223 prefixed to place them in a Zephyr-specific namespace, re-defined using ``#undef``, or 1224 conditionally excluded from compilation using ``#ifndef``. Instead, if a conflict arises with an 1225 existing definition originating from a :ref:`module <modules>`, the module's code itself needs to 1226 be modified (ideally upstream, alternatively via a change in Zephyr's own fork). 1227 1228 This rule applies to Zephyr as a project in general, regardless of the time of introduction of the 1229 macro or its current name in the tree. If a macro name is commonly used in several other well-known 1230 open source projects then the implementation in Zephyr should use that name. While there is a 1231 subjective and non-measurable component to what "commonly used" means, the ultimate goal is to offer 1232 users familiar macros. 1233 1234 Finally, this rule applies to inter-module name collisions as well: in that case both modules, prior 1235 to their inclusion, should be modified to use module-specific versions of the macro name that 1236 collides. 1237 1238Rationale 1239 Zephyr is an RTOS that comes with additional functionality and dependencies in the form of modules. 1240 Those modules are typically independent projects that may use macro names that can conflict with 1241 other modules or with Zephyr itself. Since, in the context of this documentation, Zephyr is 1242 considered the central or main project, it should implement the non-namespaced versions of the 1243 macros. Given that Zephyr uses a fork of the corresponding upstream for each module, it is always 1244 possible to patch the macro implementation in each module to avoid collisions. 1245 1246Rule A.4: C Standard Library Usage Restrictions in Zephyr Kernel 1247================================================================ 1248Severity 1249 Required 1250 1251Description 1252 The use of the C standard library functions and macros in the Zephyr kernel 1253 shall be limited to the following functions and macros from the ISO/IEC 1254 9899:2011 standard, also known as C11, and their extensions: 1255 1256 .. csv-table:: List of allowed libc functions and macros in the Zephyr kernel 1257 :header: Function,Source 1258 :widths: auto 1259 1260 abort(),ISO/IEC 9899:2011 1261 abs(),ISO/IEC 9899:2011 1262 aligned_alloc(),ISO/IEC 9899:2011 1263 assert(),ISO/IEC 9899:2011 1264 atoi(),ISO/IEC 9899:2011 1265 bsearch(),ISO/IEC 9899:2011 1266 calloc(),ISO/IEC 9899:2011 1267 exit(),ISO/IEC 9899:2011 1268 fprintf(),ISO/IEC 9899:2011 1269 fputc(),ISO/IEC 9899:2011 1270 fputs(),ISO/IEC 9899:2011 1271 free(),ISO/IEC 9899:2011 1272 fwrite(),ISO/IEC 9899:2011 1273 gmtime(),ISO/IEC 9899:2011 1274 isalnum(),ISO/IEC 9899:2011 1275 isalpha(),ISO/IEC 9899:2011 1276 iscntrl(),ISO/IEC 9899:2011 1277 isdigit(),ISO/IEC 9899:2011 1278 isgraph(),ISO/IEC 9899:2011 1279 isprint(),ISO/IEC 9899:2011 1280 isspace(),ISO/IEC 9899:2011 1281 isupper(),ISO/IEC 9899:2011 1282 isxdigit(),ISO/IEC 9899:2011 1283 labs(),ISO/IEC 9899:2011 1284 llabs(),ISO/IEC 9899:2011 1285 malloc(),ISO/IEC 9899:2011 1286 memchr(),ISO/IEC 9899:2011 1287 memcmp(),ISO/IEC 9899:2011 1288 memcpy(),ISO/IEC 9899:2011 1289 memmove(),ISO/IEC 9899:2011 1290 memset(),ISO/IEC 9899:2011 1291 perror(),ISO/IEC 9899:2011 1292 printf(),ISO/IEC 9899:2011 1293 putc(),ISO/IEC 9899:2011 1294 putchar(),ISO/IEC 9899:2011 1295 puts(),ISO/IEC 9899:2011 1296 qsort(),ISO/IEC 9899:2011 1297 rand(),ISO/IEC 9899:2011 1298 realloc(),ISO/IEC 9899:2011 1299 snprintf(),ISO/IEC 9899:2011 1300 sprintf(),ISO/IEC 9899:2011 1301 sqrt(),ISO/IEC 9899:2011 1302 sqrtf(),ISO/IEC 9899:2011 1303 srand(),ISO/IEC 9899:2011 1304 strcat(),ISO/IEC 9899:2011 1305 strchr(),ISO/IEC 9899:2011 1306 strcmp(),ISO/IEC 9899:2011 1307 strcpy(),ISO/IEC 9899:2011 1308 strcspn(),ISO/IEC 9899:2011 1309 strerror(),ISO/IEC 9899:2011 1310 strlen(),ISO/IEC 9899:2011 1311 strncat(),ISO/IEC 9899:2011 1312 strncmp(),ISO/IEC 9899:2011 1313 strncpy(),ISO/IEC 9899:2011 1314 `strnlen()`_,POSIX.1-2008 1315 strrchr(),ISO/IEC 9899:2011 1316 strspn(),ISO/IEC 9899:2011 1317 strstr(),ISO/IEC 9899:2011 1318 strtol(),ISO/IEC 9899:2011 1319 strtoll(),ISO/IEC 9899:2011 1320 strtoul(),ISO/IEC 9899:2011 1321 strtoull(),ISO/IEC 9899:2011 1322 time(),ISO/IEC 9899:2011 1323 tolower(),ISO/IEC 9899:2011 1324 toupper(),ISO/IEC 9899:2011 1325 vfprintf(),ISO/IEC 9899:2011 1326 vprintf(),ISO/IEC 9899:2011 1327 vsnprintf(),ISO/IEC 9899:2011 1328 vsprintf(),ISO/IEC 9899:2011 1329 1330 All of the functions listed above must be implemented by the 1331 :ref:`minimal libc <c_library_minimal>` to ensure that the Zephyr kernel can 1332 build with the minimal libc. 1333 1334 In addition, any functions from the above list that are not part of the 1335 ISO/IEC 9899:2011 standard must be implemented by the 1336 :ref:`common libc <c_library_common>` to ensure their availability across 1337 multiple C standard libraries. 1338 1339 Introducing new C standard library functions to the Zephyr kernel is allowed 1340 with justification given that the above requirements are satisfied. 1341 1342 Note that the use of the functions listed above are subject to secure and safe 1343 coding practices and it should not be assumed that their use in the Zephyr 1344 kernel is unconditionally permitted by being listed in this rule. 1345 1346 The "Zephyr kernel" in this context consists of the following components: 1347 1348 * Kernel (:file:`kernel`) 1349 * OS Library (:file:`lib/os`) 1350 * Architecture Port (:file:`arch`) 1351 * Logging Subsystem (:file:`subsys/logging`) 1352 1353Rationale 1354 Zephyr kernel must be able to build with the 1355 :ref:`minimal libc <c_library_minimal>`, a limited C standard library 1356 implementation that is part of the Zephyr RTOS and maintained by the Zephyr 1357 Project, to allow self-contained testing and verification of the kernel and 1358 core OS services. 1359 1360 In order to ensure that the Zephyr kernel can build with the minimal libc, it 1361 is necessary to restrict the use of the C standard library functions and macros 1362 in the Zephyr kernel to the functions and macros that are available as part of 1363 the minimal libc. 1364 1365Rule A.5: C Standard Library Usage Restrictions in Zephyr Codebase 1366================================================================== 1367Severity 1368 Required 1369 1370Description 1371 The use of the C standard library functions and macros in the Zephyr codebase 1372 shall be limited to the functions, excluding the Annex K "Bounds-checking 1373 interfaces", from the ISO/IEC 9899:2011 standard, also known as C11, unless 1374 exempted by this rule. 1375 1376 The "Zephyr codebase" in this context refers to all embedded source code files committed 1377 to the `main Zephyr repository`_, except the Zephyr kernel as defined by the 1378 :ref:`coding_guideline_libc_usage_restrictions_in_zephyr_kernel`. 1379 With embedded source code we refer to code which is meant to be executed in embedded 1380 targets, and therefore excludes host tooling, and code specific for the 1381 :ref:`native <boards_posix>` test targets. 1382 1383 The following non-ISO 9899:2011, hereinafter referred to as non-standard, 1384 functions and macros are exempt from this rule and allowed to be used in the 1385 Zephyr codebase: 1386 1387 .. csv-table:: List of allowed non-standard libc functions 1388 :header: Function,Source 1389 :widths: auto 1390 1391 `gmtime_r()`_,POSIX.1-2001 1392 `strnlen()`_,POSIX.1-2008 1393 `strtok_r()`_,POSIX.1-2001 1394 1395 All non-standard functions and macros listed above must be implemented by the 1396 :ref:`common libc <c_library_common>` in order to make sure that these 1397 functions can be made available when using a C standard library that does not 1398 implement these functions. 1399 1400 Adding a new non-standard function from common C standard libraries to the 1401 above list is allowed with justification, given that the above requirement is 1402 satisfied. However, when there exists a standard function that is functionally 1403 equivalent, the standard function shall be used. 1404 1405Rationale 1406 Some C standard libraries, such as Newlib and Picolibc, include additional 1407 functions and macros that are defined by the standards and de-facto standards 1408 that extend the ISO C standard (e.g. POSIX, Linux). 1409 1410 The ISO/IEC 9899:2011 standard does not require C compiler toolchains to 1411 include the support for these non-standard functions, and therefore using 1412 these functions can lead to compatibility issues with the third-party 1413 toolchains that come with their own C standard libraries. 1414 1415 .. _main Zephyr repository: https://github.com/zephyrproject-rtos/zephyr 1416 .. _gmtime_r(): https://pubs.opengroup.org/onlinepubs/9699919799/functions/gmtime_r.html 1417 .. _strnlen(): https://pubs.opengroup.org/onlinepubs/9699919799/functions/strlen.html 1418 .. _strtok_r(): https://pubs.opengroup.org/onlinepubs/9699919799/functions/strtok.html 1419
