FreeRTOS+POSIX
Portable Operating System Interface (POSIX threading wrapper) for FreeRTOS

On this page:

1. Introduction
2. Pre-configured example project
3. Supported features
4. FreeRTOS+POSIX source code organisation
5. Dependencies
6. Developer references and API documentation
7. Porting
8. Code Size

 

Introduction

The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. FreeRTOS+POSIX implements a small subset of the POSIX threading API. This subset allows application developers familiar with POSIX API to develop a FreeRTOS application using POSIX like threading primitives. FreeRTOS+POSIX only implements about 20% of the POSIX API. Therefore, an existing POSIX compliant application or a POSIX compliant library cannot be ported to run on FreeRTOS Kernel using only this wrapper.

 

Example Pre-configure Project

The FreeRTOS+POSIX pre-configured example is provided in a separate zip file download.

 

Currently Supported Features

FreeRTOS+POSIX partially implements IEEE Std 1003.1-2017 Edition The Open Group Technical Standard Base Specifications, Issue 7. FreeRTOS+POSIX includes implementations for the following POSIX threading header files - please refer to the FreeRTOS+POSIX API documentation for specifics on the features supported within each header file:

errno.h fcntl.h mqueue.h pthread.h sched.h semaphore.h

signal.h sys/types.h time.h unistd.h utils.h

 

FreeRTOS+POSIX Source Code Organisation

Porting related headers and implementation source code

/lib/FreeRTOS-Plus-POSIX
        |-- include
        |   |
        |   +- FreeRTOS_POSIX.h
        |   +- FreeRTOS_POSIX_internal.h
        |   +- FreeRTOS_POSIX_types.h
        |   +- portable
        |        |
        |        +- [target]
        |        |    |
        |        |    +- [development board]
        |        |            |
        |        |            +- FreeRTOS_POSIX_portable.h
        |        |
        |        +- FreeRTOS_POSIX_portable_default.h
        |
        +- source
            +- FreeRTOS_POSIX_clock.c
            +- FreeRTOS_POSIX_mqueue.c
            +- FreeRTOS_POSIX_pthread_barrier.c
            +- FreeRTOS_POSIX_pthread.c
            +- FreeRTOS_POSIX_pthread_cond.c
            +- FreeRTOS_POSIX_pthread_mutex.c
            +- FreeRTOS_POSIX_sched.c
            +- FreeRTOS_POSIX_semaphore.c
            +- FreeRTOS_POSIX_timer.c
            +- FreeRTOS_POSIX_unistd.c
            +- FreeRTOS_POSIX_utils.c

FreeRTOS+POSIX headers

	/lib/include/FreeRTOS_POSIX
                    +- errno.h
                    +- fcntl.h
                    +- mqueue.h
                    +- pthread.h
                    +- sched.h
                    +- semaphore.h
                    +- signal.h
                    +- sys
                    |    |
                    |    +- types.h
                    |
                    +- time.h
                    +- unistd.h
                    +- utils.h

 

Dependencies

Both configUSE_POSIX_ERRNO and configUSE_APPLICATION_TASK_TAG must be set to 1 in FreeRTOSConfig.h.

 

Developer References and API Documents

Please refer to the reference material (links to Doxygen output).

 

Porting

Porting Related Header Files

FreeRTOS platform specific POSIX configuration	High Level Description
/lib/FreeRTOS-Plus-POSIX/include/FreeRTOS_POSIX.h	This header file brings in dependencies required by FreeRTOS+POSIX. This file must be included before all other FreeRTOS+POSIX includes.
/lib/FreeRTOS-Plus-POSIX/include/FreeRTOS_POSIX_internal.h	FreeRTOS+POSIX internal structs and initializers. Users are not suggested to touch this file.
/lib/FreeRTOS-Plus-POSIX/include/FreeRTOS_POSIX_portable_default.h	Defaults for FreeRTOS+POSIX port-specific configuration options.
/lib/FreeRTOS-Plus-POSIX/include/portable/[vendor-directory]/FreeRTOS_POSIX_portable.h	Port-specific configuration overwrite of FreeRTOS+POSIX. As an example, /lib/FreeRTOS-Plus-POSIX/include/portable/pc/windows/FreeRTOS_POSIX_portable.h, Windows simulator uses the defaults, thus does not need to overwrite anything.

 

FreeRTOS+POSIX Include Paths

/lib/FreeRTOS-Plus-POSIX/include

/lib/FreeRTOS-Plus-POSIX/source

/lib/include/FreeRTOS_POSIX/

Note that a project only needs platform specific header from this path /lib/FreeRTOS-Plus-POSIX/include/portable.

 

Code Size

Code Size (Compiled with ARM Code Generation Tools (CGT), --silicon_version 7M4)
File	Optimisation off, in Byte	Optimisation on, in Byte (--opt_level 0 --opt_for_speed 0)
FreeRTOS_POSIX_clock.c	412	296
FreeRTOS_POSIX_mqueue.c	2016	1612
FreeRTOS_POSIX_pthread_barrier.c	294	200
FreeRTOS_POSIX_pthread.c	980	660
FreeRTOS_POSIX_pthread_cond.c	696	496
FreeRTOS_POSIX_pthread_mutex.c	848	608
FreeRTOS_POSIX_sched.c	48	32
FreeRTOS_POSIX_semaphore.c	540	380
FreeRTOS_POSIX_timer.c	972	788
FreeRTOS_POSIX_unistd.c	92	68
FreeRTOS_POSIX_utils.c	1152	768
Total	8050	5908