Invisio C Cpp Style

Invisio C/C++ Coding Standard

General Requirements

When generating or modifying C/C++ code:

• Follow the Invisio coding standard.
• Minimize unrelated formatting changes.
• Preserve existing external third-party code style.
• Use spaces only, never tabs.
• Indentation is 4 spaces.
• Opening braces use attached style.
• Braces are mandatory for all control statements.
• Internal functions must be declared static.
• Use const wherever applicable.
• All function arguments shall be named.
• Do not introduce new style variations.
• For session SQL workflows, available tables are: todos, todo_deps, inbox_entries.

AStyle Formatting

The codebase is formatted using:

--indent=spaces=4 --suffix=.InvisioStyleErr --keep-one-line-statements --indent-switches --add-braces --style=attach --A2 --keep-one-line-blocks

Generated code shall already conform to these rules.

Naming Conventions

Variables

Use camel case.

Examples:

uint16_t theRedHorse; uint16_t readOkByte; uint16_t readOKbyte;

Acronyms

Acronyms are uppercase.

Examples:

UARTreadByte UARTcomLink UARTmask SPIwriteByte

Group Prefixes

When grouping is useful:

UART_readByte UART_writeByte SPI_readByte SPI_writeByte

Numbers

Numbers are written directly without underscores.

Examples:

testSPI1layer testSPI0order HBO0readByte

Avoid additional underscores around numbers.

Type Naming

Use the following suffixes:

typedefName_t structName_s enumName_e unionName_u

Examples:

typedef uint16_t value_t;

typedef struct { uint16_t value; } settings_s;

typedef enum { LEFT, RIGHT } position_e;

Defines

Defines are uppercase.

#define THE_RED_HORSE (1)

Always place parentheses around define values.

Correct:

#define UART_TIMEOUT_MS (100)

Incorrect:

#define UART_TIMEOUT_MS 100

Doxygen Comments

File Header

/**

• @file the_read_horse.c
• Description if applicable */

Function Declaration

/**

• Function
• @param in pointer to input
• @param out pointer to output
• @ingroup groupName */ void function(uint16_t *in, uint16_t *out);

Single-Line Doxygen

/// Description #define THEREDHORSE (1)

or

#define THEREDHORSE (1) ///< Description

Header File Structure

Order shall be:

1. Doxygen file comment
2. Include guard
3. Includes
4. File-wide defines
5. Typedefs
6. Structures
7. Global variable declarations using extern
8. Function declarations
9. End include guard

Example:

#ifndef THE_RED_HORSE_H_ #define THE_RED_HORSE_H_

#include "typedef.h"

#define MAX_COUNT (10)

typedef uint16_t counter_t;

extern uint16_t globalCounter;

void readData(uint16_t *buffer);

#endif // THE_RED_HORSE_H_

Source File Structure

Order shall be:

1. Doxygen file comment
2. Includes
3. Defines
4. Typedefs
5. Structures
6. Global variables
7. Internal function declarations
8. Function definitions

Do not place extern declarations in .c files.

Functions

Internal functions must be static.

static uint16_t calculateChecksum(uint16_t value);

Use const when applicable.

static uint16_t calculateChecksum(const uint8_t *buffer, uint16_t length);

Example:

uint16_t readData(uint16_t in1, uint16_t in2) { uint16_t i = 0;

if (i == 0) {
    /* code */
} else {
    /* code */
}

i++;

return i;

}

Control Statements

Braces are always required.

Correct:

if (condition) { action(); }

Incorrect:

if (condition) action();

One-line blocks are allowed:

if ((timerClockFreq == 64000000) && (baudRate == 115200)) { timerPeriodTimesOnePointFive = 675; return; }

Boolean Conditions

Conditions must evaluate explicitly to a Boolean expression.

Incorrect:

while (count)

Correct:

while (count != 0)

Correct:

if (enabled == TRUE)

For Loops

for (i = 0; i < 10; i++) { /* code */ }

While Loops

while (condition) { /* code */ }

do { /* code */ } while (condition);

Switch Statements

Use indented cases.

Always include a default case.

Default shall be last.

Fall-through is not allowed when executable code exists between cases.

switch (condition) { case ABC: case DEF: doSomething(); break;

case XYZ:
    doSomethingElse();
    break;

default:
    handleError();
    break;

}

Expressions

Examples:

a += (c + d);

a = (a + b) / (c * d);

strp->field = str.fl - ((x & MASK) >> DISP);

Do not mix unrelated data types on the same expression line.

Pointer Style

Correct:

uint16_t *s; uint16_t *t; uint16_t *u;

Correct:

uint16_t *s, *t, *u;

Incorrect:

uint16_t* s, t, u;

Enums

typedef enum { LEFT = 0, ///< Left RIGHT = 1 ///< Right } position_e;

Structs

typedef struct { uint16_t var1; uint16_t var2; } structName_s;

Strings

Reserve space for the NULL terminator explicitly.

uint8_t myString[10 + 1];

Global Variables

• Avoid direct access when possible.
• Provide wrapper functions for read-only access.
• Use extern only in header files.
• Never place static variables in header files.

File and Folder Names

• Spaces are not allowed.
• Use the project's camel-case naming rules.
• Matching .c and .h files shall be located in the same folder.
• Group related files into folders when appropriate.

External Code

When importing external source files:

• Preserve the original code style.
• Do not reformat external code.

When copying snippets into project files:

• Convert the snippet to Invisio style.
• Add a comment indicating the original source.