FreeRTOS Hungarian Notation [duplicate]

Question

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• what is v and x means in freeRTOS task creating or used in it? 2 answers

I'm a complete newbie in RTOS and C programming, and I'm still getting used to the C good practices yet. So I opened a project which uses FreeRTOS, and I notice that the OS files use the Hungarian Notation. I know the notation a little, but faced some new "standards" in the FreeRTOS.h file, which are:

#ifndef configASSERT
    #define configASSERT( x )
    #define configASSERT_DEFINED 0
#else
    #define configASSERT_DEFINED 1
#endif

And below that,

#ifndef INCLUDE_xTaskGetSchedulerState
    #define INCLUDE_xTaskGetSchedulerState 0
#endif

#ifndef INCLUDE_xTaskGetCurrentTaskHandle
    #define INCLUDE_xTaskGetCurrentTaskHandle 0
#endif

I've seen this x - as in xTaskGetCurrentTaskHandle - everywhere. Also, v, pd and variable names like that, like in line 728 of the header in question:

#if configENABLE_BACKWARD_COMPATIBILITY == 1
    #define eTaskStateGet eTaskGetState
    #define portTickType TickType_t
    #define xTaskHandle TaskHandle_t
    #define xQueueHandle QueueHandle_t
    #define xSemaphoreHandle SemaphoreHandle_t
    #define xQueueSetHandle QueueSetHandle_t
    #define xQueueSetMemberHandle QueueSetMemberHandle_t
    #define xTimeOutType TimeOut_t
    #define xMemoryRegion MemoryRegion_t
    #define xTaskParameters TaskParameters_t
    #define xTaskStatusType TaskStatus_t
    #define xTimerHandle TimerHandle_t
    #define xCoRoutineHandle CoRoutineHandle_t
    #define pdTASK_HOOK_CODE TaskHookFunction_t
    #define portTICK_RATE_MS portTICK_PERIOD_MS

    /* Backward compatibility within the scheduler code only - these definitions
    are not really required but are included for completeness. */
    #define tmrTIMER_CALLBACK TimerCallbackFunction_t
    #define pdTASK_CODE TaskFunction_t
    #define xListItem ListItem_t
    #define xList List_t

I've searched everywhere what would those "initials" stand for, but still could not figure that out.

So, if anyone could help me to understand this, or could show me a path or something, I'd be really grateful.

Answer 1

Looking at the man

Naming Conventions

The RTOS kernel and demo application source code use the following conventions:

Variables

• Variables of type uint32_t are prefixed ul, where the 'u' denotes unsigned and the 'l' denotes long.

• Variables of type uint16_t are prefixed us, where the 'u' denotes 'unsigned' and the 's' denotes short.

• Variables of type uint8_t are prefixed uc, where the 'u' denotes 'unsigned' and the 'c' denotes char.

• Variables of non stdint types are prefixed x. Examples include BaseType_t and TickType_t, which are portable layer defined typedefs for the natural or most efficient type for the architecture and the type used to hold the RTOS tick count respectively.

• Unsigned variables of non stdint types have an additional prefix u. For example variables of type UBaseType_t (unsigned BaseType_t) are prefixed ux.

• Variables of type size_t are also prefixed x.

• Enumerated variables are prefixed e

• Pointers have an additional prefixed p, for example a pointer to a uint16_t will have prefix pus.

• In line with MISRA guides, unqualified standard char types are only permitted to hold ASCII characters and are prefixed c.

• In line with MISRA guides, variables of type char * are only permitted to hold pointers to ASCII strings and are prefixed pc.

^{Emphasis mine}

Functions

• File scope static (private) functions are prefixed with prv.

• API functions are prefixed with their return type, as per the convention defined for variables, with the addition of the prefix v for void.

• API function names start with the name of the file in which they are defined. For example vTaskDelete is defined in tasks.c, and has a void return type.

^{Emphasis mine}

Macros

• Macros are pre-fixed with the file in which they are defined. The pre-fix is lower case. For example, configUSE_PREEMPTION is defined in FreeRTOSConfig.h.

• Other than the pre-fix, macros are written in all upper case, and use an underscore to separate words.

^{Emphasis mine}