FreeRTOS_on_mbed_v1 - Please see my note book http://mbed.org/users/ken…

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Please see my note book http://mbed.org/users/kenjiArai/notebook/freertos-on-mbed-board-with-mbed-cloud-ide--never-/

This is too old.
Below is another FreeRTOS on mbed.
http://developer.mbed.org/users/rgrover1/code/FreeRTOS/
I don't know it works well or not.
I have not evaluated it.

FreeRTOS/Source/include/semphr.h@0:d4960fcea8ff, 2011-01-01 (annotated)

Committer:: kenjiArai
Date:: Sat Jan 01 11:17:45 2011 +0000
Revision:: 0:d4960fcea8ff

Who changed what in which revision?

User	Revision	Line number	New contents of line
kenjiArai	0:d4960fcea8ff	1	/*
kenjiArai	0:d4960fcea8ff	2	FreeRTOS V6.0.3 - Copyright (C) 2010 Real Time Engineers Ltd.
kenjiArai	0:d4960fcea8ff	3
kenjiArai	0:d4960fcea8ff	4	***************************************************************************
kenjiArai	0:d4960fcea8ff	5	* *
kenjiArai	0:d4960fcea8ff	6	* If you are: *
kenjiArai	0:d4960fcea8ff	7	* *
kenjiArai	0:d4960fcea8ff	8	* + New to FreeRTOS, *
kenjiArai	0:d4960fcea8ff	9	* + Wanting to learn FreeRTOS or multitasking in general quickly *
kenjiArai	0:d4960fcea8ff	10	* + Looking for basic training, *
kenjiArai	0:d4960fcea8ff	11	* + Wanting to improve your FreeRTOS skills and productivity *
kenjiArai	0:d4960fcea8ff	12	* *
kenjiArai	0:d4960fcea8ff	13	* then take a look at the FreeRTOS eBook *
kenjiArai	0:d4960fcea8ff	14	* *
kenjiArai	0:d4960fcea8ff	15	* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
kenjiArai	0:d4960fcea8ff	16	* http://www.FreeRTOS.org/Documentation *
kenjiArai	0:d4960fcea8ff	17	* *
kenjiArai	0:d4960fcea8ff	18	* A pdf reference manual is also available. Both are usually delivered *
kenjiArai	0:d4960fcea8ff	19	* to your inbox within 20 minutes to two hours when purchased between 8am *
kenjiArai	0:d4960fcea8ff	20	* and 8pm GMT (although please allow up to 24 hours in case of *
kenjiArai	0:d4960fcea8ff	21	* exceptional circumstances). Thank you for your support! *
kenjiArai	0:d4960fcea8ff	22	* *
kenjiArai	0:d4960fcea8ff	23	***************************************************************************
kenjiArai	0:d4960fcea8ff	24
kenjiArai	0:d4960fcea8ff	25	This file is part of the FreeRTOS distribution.
kenjiArai	0:d4960fcea8ff	26
kenjiArai	0:d4960fcea8ff	27	FreeRTOS is free software; you can redistribute it and/or modify it under
kenjiArai	0:d4960fcea8ff	28	the terms of the GNU General Public License (version 2) as published by the
kenjiArai	0:d4960fcea8ff	29	Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
kenjiArai	0:d4960fcea8ff	30	*NOTE* The exception to the GPL is included to allow you to distribute
kenjiArai	0:d4960fcea8ff	31	a combined work that includes FreeRTOS without being obliged to provide the
kenjiArai	0:d4960fcea8ff	32	source code for proprietary components outside of the FreeRTOS kernel.
kenjiArai	0:d4960fcea8ff	33	FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
kenjiArai	0:d4960fcea8ff	34	ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
kenjiArai	0:d4960fcea8ff	35	FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
kenjiArai	0:d4960fcea8ff	36	more details. You should have received a copy of the GNU General Public
kenjiArai	0:d4960fcea8ff	37	License and the FreeRTOS license exception along with FreeRTOS; if not it
kenjiArai	0:d4960fcea8ff	38	can be viewed here: http://www.freertos.org/a00114.html and also obtained
kenjiArai	0:d4960fcea8ff	39	by writing to Richard Barry, contact details for whom are available on the
kenjiArai	0:d4960fcea8ff	40	FreeRTOS WEB site.
kenjiArai	0:d4960fcea8ff	41
kenjiArai	0:d4960fcea8ff	42	1 tab == 4 spaces!
kenjiArai	0:d4960fcea8ff	43
kenjiArai	0:d4960fcea8ff	44	http://www.FreeRTOS.org - Documentation, latest information, license and
kenjiArai	0:d4960fcea8ff	45	contact details.
kenjiArai	0:d4960fcea8ff	46
kenjiArai	0:d4960fcea8ff	47	http://www.SafeRTOS.com - A version that is certified for use in safety
kenjiArai	0:d4960fcea8ff	48	critical systems.
kenjiArai	0:d4960fcea8ff	49
kenjiArai	0:d4960fcea8ff	50	http://www.OpenRTOS.com - Commercial support, development, porting,
kenjiArai	0:d4960fcea8ff	51	licensing and training services.
kenjiArai	0:d4960fcea8ff	52	*/
kenjiArai	0:d4960fcea8ff	53
kenjiArai	0:d4960fcea8ff	54	#ifndef INC_FREERTOS_H
kenjiArai	0:d4960fcea8ff	55	#error "#include FreeRTOS.h" must appear in source files before "#include semphr.h"
kenjiArai	0:d4960fcea8ff	56	#endif
kenjiArai	0:d4960fcea8ff	57
kenjiArai	0:d4960fcea8ff	58	#ifndef SEMAPHORE_H
kenjiArai	0:d4960fcea8ff	59	#define SEMAPHORE_H
kenjiArai	0:d4960fcea8ff	60
kenjiArai	0:d4960fcea8ff	61	#include "queue.h"
kenjiArai	0:d4960fcea8ff	62
kenjiArai	0:d4960fcea8ff	63	typedef xQueueHandle xSemaphoreHandle;
kenjiArai	0:d4960fcea8ff	64
kenjiArai	0:d4960fcea8ff	65	#define semBINARY_SEMAPHORE_QUEUE_LENGTH ( ( unsigned char ) 1 )
kenjiArai	0:d4960fcea8ff	66	#define semSEMAPHORE_QUEUE_ITEM_LENGTH ( ( unsigned char ) 0 )
kenjiArai	0:d4960fcea8ff	67	#define semGIVE_BLOCK_TIME ( ( portTickType ) 0 )
kenjiArai	0:d4960fcea8ff	68
kenjiArai	0:d4960fcea8ff	69
kenjiArai	0:d4960fcea8ff	70	/**
kenjiArai	0:d4960fcea8ff	71	* semphr. h
kenjiArai	0:d4960fcea8ff	72	* <pre>vSemaphoreCreateBinary( xSemaphoreHandle xSemaphore )</pre>
kenjiArai	0:d4960fcea8ff	73	*
kenjiArai	0:d4960fcea8ff	74	* <i>Macro</i> that implements a semaphore by using the existing queue mechanism.
kenjiArai	0:d4960fcea8ff	75	* The queue length is 1 as this is a binary semaphore. The data size is 0
kenjiArai	0:d4960fcea8ff	76	* as we don't want to actually store any data - we just want to know if the
kenjiArai	0:d4960fcea8ff	77	* queue is empty or full.
kenjiArai	0:d4960fcea8ff	78	*
kenjiArai	0:d4960fcea8ff	79	* This type of semaphore can be used for pure synchronisation between tasks or
kenjiArai	0:d4960fcea8ff	80	* between an interrupt and a task. The semaphore need not be given back once
kenjiArai	0:d4960fcea8ff	81	* obtained, so one task/interrupt can continuously 'give' the semaphore while
kenjiArai	0:d4960fcea8ff	82	* another continuously 'takes' the semaphore. For this reason this type of
kenjiArai	0:d4960fcea8ff	83	* semaphore does not use a priority inheritance mechanism. For an alternative
kenjiArai	0:d4960fcea8ff	84	* that does use priority inheritance see xSemaphoreCreateMutex().
kenjiArai	0:d4960fcea8ff	85	*
kenjiArai	0:d4960fcea8ff	86	* @param xSemaphore Handle to the created semaphore. Should be of type xSemaphoreHandle.
kenjiArai	0:d4960fcea8ff	87	*
kenjiArai	0:d4960fcea8ff	88	* Example usage:
kenjiArai	0:d4960fcea8ff	89	<pre>
kenjiArai	0:d4960fcea8ff	90	xSemaphoreHandle xSemaphore;
kenjiArai	0:d4960fcea8ff	91
kenjiArai	0:d4960fcea8ff	92	void vATask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	93	{
kenjiArai	0:d4960fcea8ff	94	// Semaphore cannot be used before a call to vSemaphoreCreateBinary ().
kenjiArai	0:d4960fcea8ff	95	// This is a macro so pass the variable in directly.
kenjiArai	0:d4960fcea8ff	96	vSemaphoreCreateBinary( xSemaphore );
kenjiArai	0:d4960fcea8ff	97
kenjiArai	0:d4960fcea8ff	98	if( xSemaphore != NULL )
kenjiArai	0:d4960fcea8ff	99	{
kenjiArai	0:d4960fcea8ff	100	// The semaphore was created successfully.
kenjiArai	0:d4960fcea8ff	101	// The semaphore can now be used.
kenjiArai	0:d4960fcea8ff	102	}
kenjiArai	0:d4960fcea8ff	103	}
kenjiArai	0:d4960fcea8ff	104	</pre>
kenjiArai	0:d4960fcea8ff	105	* \defgroup vSemaphoreCreateBinary vSemaphoreCreateBinary
kenjiArai	0:d4960fcea8ff	106	* \ingroup Semaphores
kenjiArai	0:d4960fcea8ff	107	*/
kenjiArai	0:d4960fcea8ff	108	#define vSemaphoreCreateBinary( xSemaphore ) { \
kenjiArai	0:d4960fcea8ff	109	xSemaphore = xQueueCreate( ( unsigned portBASE_TYPE ) 1, semSEMAPHORE_QUEUE_ITEM_LENGTH ); \
kenjiArai	0:d4960fcea8ff	110	if( xSemaphore != NULL ) \
kenjiArai	0:d4960fcea8ff	111	{ \
kenjiArai	0:d4960fcea8ff	112	xSemaphoreGive( xSemaphore ); \
kenjiArai	0:d4960fcea8ff	113	} \
kenjiArai	0:d4960fcea8ff	114	}
kenjiArai	0:d4960fcea8ff	115
kenjiArai	0:d4960fcea8ff	116	/**
kenjiArai	0:d4960fcea8ff	117	* semphr. h
kenjiArai	0:d4960fcea8ff	118	* <pre>xSemaphoreTake(
kenjiArai	0:d4960fcea8ff	119	* xSemaphoreHandle xSemaphore,
kenjiArai	0:d4960fcea8ff	120	* portTickType xBlockTime
kenjiArai	0:d4960fcea8ff	121	* )</pre>
kenjiArai	0:d4960fcea8ff	122	*
kenjiArai	0:d4960fcea8ff	123	* <i>Macro</i> to obtain a semaphore. The semaphore must have previously been
kenjiArai	0:d4960fcea8ff	124	* created with a call to vSemaphoreCreateBinary(), xSemaphoreCreateMutex() or
kenjiArai	0:d4960fcea8ff	125	* xSemaphoreCreateCounting().
kenjiArai	0:d4960fcea8ff	126	*
kenjiArai	0:d4960fcea8ff	127	* @param xSemaphore A handle to the semaphore being taken - obtained when
kenjiArai	0:d4960fcea8ff	128	* the semaphore was created.
kenjiArai	0:d4960fcea8ff	129	*
kenjiArai	0:d4960fcea8ff	130	* @param xBlockTime The time in ticks to wait for the semaphore to become
kenjiArai	0:d4960fcea8ff	131	* available. The macro portTICK_RATE_MS can be used to convert this to a
kenjiArai	0:d4960fcea8ff	132	* real time. A block time of zero can be used to poll the semaphore. A block
kenjiArai	0:d4960fcea8ff	133	* time of portMAX_DELAY can be used to block indefinitely (provided
kenjiArai	0:d4960fcea8ff	134	* INCLUDE_vTaskSuspend is set to 1 in FreeRTOSConfig.h).
kenjiArai	0:d4960fcea8ff	135	*
kenjiArai	0:d4960fcea8ff	136	* @return pdTRUE if the semaphore was obtained. pdFALSE
kenjiArai	0:d4960fcea8ff	137	* if xBlockTime expired without the semaphore becoming available.
kenjiArai	0:d4960fcea8ff	138	*
kenjiArai	0:d4960fcea8ff	139	* Example usage:
kenjiArai	0:d4960fcea8ff	140	<pre>
kenjiArai	0:d4960fcea8ff	141	xSemaphoreHandle xSemaphore = NULL;
kenjiArai	0:d4960fcea8ff	142
kenjiArai	0:d4960fcea8ff	143	// A task that creates a semaphore.
kenjiArai	0:d4960fcea8ff	144	void vATask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	145	{
kenjiArai	0:d4960fcea8ff	146	// Create the semaphore to guard a shared resource.
kenjiArai	0:d4960fcea8ff	147	vSemaphoreCreateBinary( xSemaphore );
kenjiArai	0:d4960fcea8ff	148	}
kenjiArai	0:d4960fcea8ff	149
kenjiArai	0:d4960fcea8ff	150	// A task that uses the semaphore.
kenjiArai	0:d4960fcea8ff	151	void vAnotherTask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	152	{
kenjiArai	0:d4960fcea8ff	153	// ... Do other things.
kenjiArai	0:d4960fcea8ff	154
kenjiArai	0:d4960fcea8ff	155	if( xSemaphore != NULL )
kenjiArai	0:d4960fcea8ff	156	{
kenjiArai	0:d4960fcea8ff	157	// See if we can obtain the semaphore. If the semaphore is not available
kenjiArai	0:d4960fcea8ff	158	// wait 10 ticks to see if it becomes free.
kenjiArai	0:d4960fcea8ff	159	if( xSemaphoreTake( xSemaphore, ( portTickType ) 10 ) == pdTRUE )
kenjiArai	0:d4960fcea8ff	160	{
kenjiArai	0:d4960fcea8ff	161	// We were able to obtain the semaphore and can now access the
kenjiArai	0:d4960fcea8ff	162	// shared resource.
kenjiArai	0:d4960fcea8ff	163
kenjiArai	0:d4960fcea8ff	164	// ...
kenjiArai	0:d4960fcea8ff	165
kenjiArai	0:d4960fcea8ff	166	// We have finished accessing the shared resource. Release the
kenjiArai	0:d4960fcea8ff	167	// semaphore.
kenjiArai	0:d4960fcea8ff	168	xSemaphoreGive( xSemaphore );
kenjiArai	0:d4960fcea8ff	169	}
kenjiArai	0:d4960fcea8ff	170	else
kenjiArai	0:d4960fcea8ff	171	{
kenjiArai	0:d4960fcea8ff	172	// We could not obtain the semaphore and can therefore not access
kenjiArai	0:d4960fcea8ff	173	// the shared resource safely.
kenjiArai	0:d4960fcea8ff	174	}
kenjiArai	0:d4960fcea8ff	175	}
kenjiArai	0:d4960fcea8ff	176	}
kenjiArai	0:d4960fcea8ff	177	</pre>
kenjiArai	0:d4960fcea8ff	178	* \defgroup xSemaphoreTake xSemaphoreTake
kenjiArai	0:d4960fcea8ff	179	* \ingroup Semaphores
kenjiArai	0:d4960fcea8ff	180	*/
kenjiArai	0:d4960fcea8ff	181	#define xSemaphoreTake( xSemaphore, xBlockTime ) xQueueGenericReceive( ( xQueueHandle ) xSemaphore, NULL, xBlockTime, pdFALSE )
kenjiArai	0:d4960fcea8ff	182
kenjiArai	0:d4960fcea8ff	183	/**
kenjiArai	0:d4960fcea8ff	184	* semphr. h
kenjiArai	0:d4960fcea8ff	185	* xSemaphoreTakeRecursive(
kenjiArai	0:d4960fcea8ff	186	* xSemaphoreHandle xMutex,
kenjiArai	0:d4960fcea8ff	187	* portTickType xBlockTime
kenjiArai	0:d4960fcea8ff	188	* )
kenjiArai	0:d4960fcea8ff	189	*
kenjiArai	0:d4960fcea8ff	190	* <i>Macro</i> to recursively obtain, or 'take', a mutex type semaphore.
kenjiArai	0:d4960fcea8ff	191	* The mutex must have previously been created using a call to
kenjiArai	0:d4960fcea8ff	192	* xSemaphoreCreateRecursiveMutex();
kenjiArai	0:d4960fcea8ff	193	*
kenjiArai	0:d4960fcea8ff	194	* configUSE_RECURSIVE_MUTEXES must be set to 1 in FreeRTOSConfig.h for this
kenjiArai	0:d4960fcea8ff	195	* macro to be available.
kenjiArai	0:d4960fcea8ff	196	*
kenjiArai	0:d4960fcea8ff	197	* This macro must not be used on mutexes created using xSemaphoreCreateMutex().
kenjiArai	0:d4960fcea8ff	198	*
kenjiArai	0:d4960fcea8ff	199	* A mutex used recursively can be 'taken' repeatedly by the owner. The mutex
kenjiArai	0:d4960fcea8ff	200	* doesn't become available again until the owner has called
kenjiArai	0:d4960fcea8ff	201	* xSemaphoreGiveRecursive() for each successful 'take' request. For example,
kenjiArai	0:d4960fcea8ff	202	* if a task successfully 'takes' the same mutex 5 times then the mutex will
kenjiArai	0:d4960fcea8ff	203	* not be available to any other task until it has also 'given' the mutex back
kenjiArai	0:d4960fcea8ff	204	* exactly five times.
kenjiArai	0:d4960fcea8ff	205	*
kenjiArai	0:d4960fcea8ff	206	* @param xMutex A handle to the mutex being obtained. This is the
kenjiArai	0:d4960fcea8ff	207	* handle returned by xSemaphoreCreateRecursiveMutex();
kenjiArai	0:d4960fcea8ff	208	*
kenjiArai	0:d4960fcea8ff	209	* @param xBlockTime The time in ticks to wait for the semaphore to become
kenjiArai	0:d4960fcea8ff	210	* available. The macro portTICK_RATE_MS can be used to convert this to a
kenjiArai	0:d4960fcea8ff	211	* real time. A block time of zero can be used to poll the semaphore. If
kenjiArai	0:d4960fcea8ff	212	* the task already owns the semaphore then xSemaphoreTakeRecursive() will
kenjiArai	0:d4960fcea8ff	213	* return immediately no matter what the value of xBlockTime.
kenjiArai	0:d4960fcea8ff	214	*
kenjiArai	0:d4960fcea8ff	215	* @return pdTRUE if the semaphore was obtained. pdFALSE if xBlockTime
kenjiArai	0:d4960fcea8ff	216	* expired without the semaphore becoming available.
kenjiArai	0:d4960fcea8ff	217	*
kenjiArai	0:d4960fcea8ff	218	* Example usage:
kenjiArai	0:d4960fcea8ff	219	<pre>
kenjiArai	0:d4960fcea8ff	220	xSemaphoreHandle xMutex = NULL;
kenjiArai	0:d4960fcea8ff	221
kenjiArai	0:d4960fcea8ff	222	// A task that creates a mutex.
kenjiArai	0:d4960fcea8ff	223	void vATask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	224	{
kenjiArai	0:d4960fcea8ff	225	// Create the mutex to guard a shared resource.
kenjiArai	0:d4960fcea8ff	226	xMutex = xSemaphoreCreateRecursiveMutex();
kenjiArai	0:d4960fcea8ff	227	}
kenjiArai	0:d4960fcea8ff	228
kenjiArai	0:d4960fcea8ff	229	// A task that uses the mutex.
kenjiArai	0:d4960fcea8ff	230	void vAnotherTask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	231	{
kenjiArai	0:d4960fcea8ff	232	// ... Do other things.
kenjiArai	0:d4960fcea8ff	233
kenjiArai	0:d4960fcea8ff	234	if( xMutex != NULL )
kenjiArai	0:d4960fcea8ff	235	{
kenjiArai	0:d4960fcea8ff	236	// See if we can obtain the mutex. If the mutex is not available
kenjiArai	0:d4960fcea8ff	237	// wait 10 ticks to see if it becomes free.
kenjiArai	0:d4960fcea8ff	238	if( xSemaphoreTakeRecursive( xSemaphore, ( portTickType ) 10 ) == pdTRUE )
kenjiArai	0:d4960fcea8ff	239	{
kenjiArai	0:d4960fcea8ff	240	// We were able to obtain the mutex and can now access the
kenjiArai	0:d4960fcea8ff	241	// shared resource.
kenjiArai	0:d4960fcea8ff	242
kenjiArai	0:d4960fcea8ff	243	// ...
kenjiArai	0:d4960fcea8ff	244	// For some reason due to the nature of the code further calls to
kenjiArai	0:d4960fcea8ff	245	// xSemaphoreTakeRecursive() are made on the same mutex. In real
kenjiArai	0:d4960fcea8ff	246	// code these would not be just sequential calls as this would make
kenjiArai	0:d4960fcea8ff	247	// no sense. Instead the calls are likely to be buried inside
kenjiArai	0:d4960fcea8ff	248	// a more complex call structure.
kenjiArai	0:d4960fcea8ff	249	xSemaphoreTakeRecursive( xMutex, ( portTickType ) 10 );
kenjiArai	0:d4960fcea8ff	250	xSemaphoreTakeRecursive( xMutex, ( portTickType ) 10 );
kenjiArai	0:d4960fcea8ff	251
kenjiArai	0:d4960fcea8ff	252	// The mutex has now been 'taken' three times, so will not be
kenjiArai	0:d4960fcea8ff	253	// available to another task until it has also been given back
kenjiArai	0:d4960fcea8ff	254	// three times. Again it is unlikely that real code would have
kenjiArai	0:d4960fcea8ff	255	// these calls sequentially, but instead buried in a more complex
kenjiArai	0:d4960fcea8ff	256	// call structure. This is just for illustrative purposes.
kenjiArai	0:d4960fcea8ff	257	xSemaphoreGiveRecursive( xMutex );
kenjiArai	0:d4960fcea8ff	258	xSemaphoreGiveRecursive( xMutex );
kenjiArai	0:d4960fcea8ff	259	xSemaphoreGiveRecursive( xMutex );
kenjiArai	0:d4960fcea8ff	260
kenjiArai	0:d4960fcea8ff	261	// Now the mutex can be taken by other tasks.
kenjiArai	0:d4960fcea8ff	262	}
kenjiArai	0:d4960fcea8ff	263	else
kenjiArai	0:d4960fcea8ff	264	{
kenjiArai	0:d4960fcea8ff	265	// We could not obtain the mutex and can therefore not access
kenjiArai	0:d4960fcea8ff	266	// the shared resource safely.
kenjiArai	0:d4960fcea8ff	267	}
kenjiArai	0:d4960fcea8ff	268	}
kenjiArai	0:d4960fcea8ff	269	}
kenjiArai	0:d4960fcea8ff	270	</pre>
kenjiArai	0:d4960fcea8ff	271	* \defgroup xSemaphoreTakeRecursive xSemaphoreTakeRecursive
kenjiArai	0:d4960fcea8ff	272	* \ingroup Semaphores
kenjiArai	0:d4960fcea8ff	273	*/
kenjiArai	0:d4960fcea8ff	274	#define xSemaphoreTakeRecursive( xMutex, xBlockTime ) xQueueTakeMutexRecursive( xMutex, xBlockTime )
kenjiArai	0:d4960fcea8ff	275
kenjiArai	0:d4960fcea8ff	276
kenjiArai	0:d4960fcea8ff	277	/*
kenjiArai	0:d4960fcea8ff	278	* xSemaphoreAltTake() is an alternative version of xSemaphoreTake().
kenjiArai	0:d4960fcea8ff	279	*
kenjiArai	0:d4960fcea8ff	280	* The source code that implements the alternative (Alt) API is much
kenjiArai	0:d4960fcea8ff	281	* simpler because it executes everything from within a critical section.
kenjiArai	0:d4960fcea8ff	282	* This is the approach taken by many other RTOSes, but FreeRTOS.org has the
kenjiArai	0:d4960fcea8ff	283	* preferred fully featured API too. The fully featured API has more
kenjiArai	0:d4960fcea8ff	284	* complex code that takes longer to execute, but makes much less use of
kenjiArai	0:d4960fcea8ff	285	* critical sections. Therefore the alternative API sacrifices interrupt
kenjiArai	0:d4960fcea8ff	286	* responsiveness to gain execution speed, whereas the fully featured API
kenjiArai	0:d4960fcea8ff	287	* sacrifices execution speed to ensure better interrupt responsiveness.
kenjiArai	0:d4960fcea8ff	288	*/
kenjiArai	0:d4960fcea8ff	289	#define xSemaphoreAltTake( xSemaphore, xBlockTime ) xQueueAltGenericReceive( ( xQueueHandle ) xSemaphore, NULL, xBlockTime, pdFALSE )
kenjiArai	0:d4960fcea8ff	290
kenjiArai	0:d4960fcea8ff	291	/**
kenjiArai	0:d4960fcea8ff	292	* semphr. h
kenjiArai	0:d4960fcea8ff	293	* <pre>xSemaphoreGive( xSemaphoreHandle xSemaphore )</pre>
kenjiArai	0:d4960fcea8ff	294	*
kenjiArai	0:d4960fcea8ff	295	* <i>Macro</i> to release a semaphore. The semaphore must have previously been
kenjiArai	0:d4960fcea8ff	296	* created with a call to vSemaphoreCreateBinary(), xSemaphoreCreateMutex() or
kenjiArai	0:d4960fcea8ff	297	* xSemaphoreCreateCounting(). and obtained using sSemaphoreTake().
kenjiArai	0:d4960fcea8ff	298	*
kenjiArai	0:d4960fcea8ff	299	* This macro must not be used from an ISR. See xSemaphoreGiveFromISR () for
kenjiArai	0:d4960fcea8ff	300	* an alternative which can be used from an ISR.
kenjiArai	0:d4960fcea8ff	301	*
kenjiArai	0:d4960fcea8ff	302	* This macro must also not be used on semaphores created using
kenjiArai	0:d4960fcea8ff	303	* xSemaphoreCreateRecursiveMutex().
kenjiArai	0:d4960fcea8ff	304	*
kenjiArai	0:d4960fcea8ff	305	* @param xSemaphore A handle to the semaphore being released. This is the
kenjiArai	0:d4960fcea8ff	306	* handle returned when the semaphore was created.
kenjiArai	0:d4960fcea8ff	307	*
kenjiArai	0:d4960fcea8ff	308	* @return pdTRUE if the semaphore was released. pdFALSE if an error occurred.
kenjiArai	0:d4960fcea8ff	309	* Semaphores are implemented using queues. An error can occur if there is
kenjiArai	0:d4960fcea8ff	310	* no space on the queue to post a message - indicating that the
kenjiArai	0:d4960fcea8ff	311	* semaphore was not first obtained correctly.
kenjiArai	0:d4960fcea8ff	312	*
kenjiArai	0:d4960fcea8ff	313	* Example usage:
kenjiArai	0:d4960fcea8ff	314	<pre>
kenjiArai	0:d4960fcea8ff	315	xSemaphoreHandle xSemaphore = NULL;
kenjiArai	0:d4960fcea8ff	316
kenjiArai	0:d4960fcea8ff	317	void vATask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	318	{
kenjiArai	0:d4960fcea8ff	319	// Create the semaphore to guard a shared resource.
kenjiArai	0:d4960fcea8ff	320	vSemaphoreCreateBinary( xSemaphore );
kenjiArai	0:d4960fcea8ff	321
kenjiArai	0:d4960fcea8ff	322	if( xSemaphore != NULL )
kenjiArai	0:d4960fcea8ff	323	{
kenjiArai	0:d4960fcea8ff	324	if( xSemaphoreGive( xSemaphore ) != pdTRUE )
kenjiArai	0:d4960fcea8ff	325	{
kenjiArai	0:d4960fcea8ff	326	// We would expect this call to fail because we cannot give
kenjiArai	0:d4960fcea8ff	327	// a semaphore without first "taking" it!
kenjiArai	0:d4960fcea8ff	328	}
kenjiArai	0:d4960fcea8ff	329
kenjiArai	0:d4960fcea8ff	330	// Obtain the semaphore - don't block if the semaphore is not
kenjiArai	0:d4960fcea8ff	331	// immediately available.
kenjiArai	0:d4960fcea8ff	332	if( xSemaphoreTake( xSemaphore, ( portTickType ) 0 ) )
kenjiArai	0:d4960fcea8ff	333	{
kenjiArai	0:d4960fcea8ff	334	// We now have the semaphore and can access the shared resource.
kenjiArai	0:d4960fcea8ff	335
kenjiArai	0:d4960fcea8ff	336	// ...
kenjiArai	0:d4960fcea8ff	337
kenjiArai	0:d4960fcea8ff	338	// We have finished accessing the shared resource so can free the
kenjiArai	0:d4960fcea8ff	339	// semaphore.
kenjiArai	0:d4960fcea8ff	340	if( xSemaphoreGive( xSemaphore ) != pdTRUE )
kenjiArai	0:d4960fcea8ff	341	{
kenjiArai	0:d4960fcea8ff	342	// We would not expect this call to fail because we must have
kenjiArai	0:d4960fcea8ff	343	// obtained the semaphore to get here.
kenjiArai	0:d4960fcea8ff	344	}
kenjiArai	0:d4960fcea8ff	345	}
kenjiArai	0:d4960fcea8ff	346	}
kenjiArai	0:d4960fcea8ff	347	}
kenjiArai	0:d4960fcea8ff	348	</pre>
kenjiArai	0:d4960fcea8ff	349	* \defgroup xSemaphoreGive xSemaphoreGive
kenjiArai	0:d4960fcea8ff	350	* \ingroup Semaphores
kenjiArai	0:d4960fcea8ff	351	*/
kenjiArai	0:d4960fcea8ff	352	#define xSemaphoreGive( xSemaphore ) xQueueGenericSend( ( xQueueHandle ) xSemaphore, NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )
kenjiArai	0:d4960fcea8ff	353
kenjiArai	0:d4960fcea8ff	354	/**
kenjiArai	0:d4960fcea8ff	355	* semphr. h
kenjiArai	0:d4960fcea8ff	356	* <pre>xSemaphoreGiveRecursive( xSemaphoreHandle xMutex )</pre>
kenjiArai	0:d4960fcea8ff	357	*
kenjiArai	0:d4960fcea8ff	358	* <i>Macro</i> to recursively release, or 'give', a mutex type semaphore.
kenjiArai	0:d4960fcea8ff	359	* The mutex must have previously been created using a call to
kenjiArai	0:d4960fcea8ff	360	* xSemaphoreCreateRecursiveMutex();
kenjiArai	0:d4960fcea8ff	361	*
kenjiArai	0:d4960fcea8ff	362	* configUSE_RECURSIVE_MUTEXES must be set to 1 in FreeRTOSConfig.h for this
kenjiArai	0:d4960fcea8ff	363	* macro to be available.
kenjiArai	0:d4960fcea8ff	364	*
kenjiArai	0:d4960fcea8ff	365	* This macro must not be used on mutexes created using xSemaphoreCreateMutex().
kenjiArai	0:d4960fcea8ff	366	*
kenjiArai	0:d4960fcea8ff	367	* A mutex used recursively can be 'taken' repeatedly by the owner. The mutex
kenjiArai	0:d4960fcea8ff	368	* doesn't become available again until the owner has called
kenjiArai	0:d4960fcea8ff	369	* xSemaphoreGiveRecursive() for each successful 'take' request. For example,
kenjiArai	0:d4960fcea8ff	370	* if a task successfully 'takes' the same mutex 5 times then the mutex will
kenjiArai	0:d4960fcea8ff	371	* not be available to any other task until it has also 'given' the mutex back
kenjiArai	0:d4960fcea8ff	372	* exactly five times.
kenjiArai	0:d4960fcea8ff	373	*
kenjiArai	0:d4960fcea8ff	374	* @param xMutex A handle to the mutex being released, or 'given'. This is the
kenjiArai	0:d4960fcea8ff	375	* handle returned by xSemaphoreCreateMutex();
kenjiArai	0:d4960fcea8ff	376	*
kenjiArai	0:d4960fcea8ff	377	* @return pdTRUE if the semaphore was given.
kenjiArai	0:d4960fcea8ff	378	*
kenjiArai	0:d4960fcea8ff	379	* Example usage:
kenjiArai	0:d4960fcea8ff	380	<pre>
kenjiArai	0:d4960fcea8ff	381	xSemaphoreHandle xMutex = NULL;
kenjiArai	0:d4960fcea8ff	382
kenjiArai	0:d4960fcea8ff	383	// A task that creates a mutex.
kenjiArai	0:d4960fcea8ff	384	void vATask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	385	{
kenjiArai	0:d4960fcea8ff	386	// Create the mutex to guard a shared resource.
kenjiArai	0:d4960fcea8ff	387	xMutex = xSemaphoreCreateRecursiveMutex();
kenjiArai	0:d4960fcea8ff	388	}
kenjiArai	0:d4960fcea8ff	389
kenjiArai	0:d4960fcea8ff	390	// A task that uses the mutex.
kenjiArai	0:d4960fcea8ff	391	void vAnotherTask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	392	{
kenjiArai	0:d4960fcea8ff	393	// ... Do other things.
kenjiArai	0:d4960fcea8ff	394
kenjiArai	0:d4960fcea8ff	395	if( xMutex != NULL )
kenjiArai	0:d4960fcea8ff	396	{
kenjiArai	0:d4960fcea8ff	397	// See if we can obtain the mutex. If the mutex is not available
kenjiArai	0:d4960fcea8ff	398	// wait 10 ticks to see if it becomes free.
kenjiArai	0:d4960fcea8ff	399	if( xSemaphoreTakeRecursive( xMutex, ( portTickType ) 10 ) == pdTRUE )
kenjiArai	0:d4960fcea8ff	400	{
kenjiArai	0:d4960fcea8ff	401	// We were able to obtain the mutex and can now access the
kenjiArai	0:d4960fcea8ff	402	// shared resource.
kenjiArai	0:d4960fcea8ff	403
kenjiArai	0:d4960fcea8ff	404	// ...
kenjiArai	0:d4960fcea8ff	405	// For some reason due to the nature of the code further calls to
kenjiArai	0:d4960fcea8ff	406	// xSemaphoreTakeRecursive() are made on the same mutex. In real
kenjiArai	0:d4960fcea8ff	407	// code these would not be just sequential calls as this would make
kenjiArai	0:d4960fcea8ff	408	// no sense. Instead the calls are likely to be buried inside
kenjiArai	0:d4960fcea8ff	409	// a more complex call structure.
kenjiArai	0:d4960fcea8ff	410	xSemaphoreTakeRecursive( xMutex, ( portTickType ) 10 );
kenjiArai	0:d4960fcea8ff	411	xSemaphoreTakeRecursive( xMutex, ( portTickType ) 10 );
kenjiArai	0:d4960fcea8ff	412
kenjiArai	0:d4960fcea8ff	413	// The mutex has now been 'taken' three times, so will not be
kenjiArai	0:d4960fcea8ff	414	// available to another task until it has also been given back
kenjiArai	0:d4960fcea8ff	415	// three times. Again it is unlikely that real code would have
kenjiArai	0:d4960fcea8ff	416	// these calls sequentially, it would be more likely that the calls
kenjiArai	0:d4960fcea8ff	417	// to xSemaphoreGiveRecursive() would be called as a call stack
kenjiArai	0:d4960fcea8ff	418	// unwound. This is just for demonstrative purposes.
kenjiArai	0:d4960fcea8ff	419	xSemaphoreGiveRecursive( xMutex );
kenjiArai	0:d4960fcea8ff	420	xSemaphoreGiveRecursive( xMutex );
kenjiArai	0:d4960fcea8ff	421	xSemaphoreGiveRecursive( xMutex );
kenjiArai	0:d4960fcea8ff	422
kenjiArai	0:d4960fcea8ff	423	// Now the mutex can be taken by other tasks.
kenjiArai	0:d4960fcea8ff	424	}
kenjiArai	0:d4960fcea8ff	425	else
kenjiArai	0:d4960fcea8ff	426	{
kenjiArai	0:d4960fcea8ff	427	// We could not obtain the mutex and can therefore not access
kenjiArai	0:d4960fcea8ff	428	// the shared resource safely.
kenjiArai	0:d4960fcea8ff	429	}
kenjiArai	0:d4960fcea8ff	430	}
kenjiArai	0:d4960fcea8ff	431	}
kenjiArai	0:d4960fcea8ff	432	</pre>
kenjiArai	0:d4960fcea8ff	433	* \defgroup xSemaphoreGiveRecursive xSemaphoreGiveRecursive
kenjiArai	0:d4960fcea8ff	434	* \ingroup Semaphores
kenjiArai	0:d4960fcea8ff	435	*/
kenjiArai	0:d4960fcea8ff	436	#define xSemaphoreGiveRecursive( xMutex ) xQueueGiveMutexRecursive( xMutex )
kenjiArai	0:d4960fcea8ff	437
kenjiArai	0:d4960fcea8ff	438	/*
kenjiArai	0:d4960fcea8ff	439	* xSemaphoreAltGive() is an alternative version of xSemaphoreGive().
kenjiArai	0:d4960fcea8ff	440	*
kenjiArai	0:d4960fcea8ff	441	* The source code that implements the alternative (Alt) API is much
kenjiArai	0:d4960fcea8ff	442	* simpler because it executes everything from within a critical section.
kenjiArai	0:d4960fcea8ff	443	* This is the approach taken by many other RTOSes, but FreeRTOS.org has the
kenjiArai	0:d4960fcea8ff	444	* preferred fully featured API too. The fully featured API has more
kenjiArai	0:d4960fcea8ff	445	* complex code that takes longer to execute, but makes much less use of
kenjiArai	0:d4960fcea8ff	446	* critical sections. Therefore the alternative API sacrifices interrupt
kenjiArai	0:d4960fcea8ff	447	* responsiveness to gain execution speed, whereas the fully featured API
kenjiArai	0:d4960fcea8ff	448	* sacrifices execution speed to ensure better interrupt responsiveness.
kenjiArai	0:d4960fcea8ff	449	*/
kenjiArai	0:d4960fcea8ff	450	#define xSemaphoreAltGive( xSemaphore ) xQueueAltGenericSend( ( xQueueHandle ) xSemaphore, NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )
kenjiArai	0:d4960fcea8ff	451
kenjiArai	0:d4960fcea8ff	452	/**
kenjiArai	0:d4960fcea8ff	453	* semphr. h
kenjiArai	0:d4960fcea8ff	454	* <pre>
kenjiArai	0:d4960fcea8ff	455	xSemaphoreGiveFromISR(
kenjiArai	0:d4960fcea8ff	456	xSemaphoreHandle xSemaphore,
kenjiArai	0:d4960fcea8ff	457	signed portBASE_TYPE *pxHigherPriorityTaskWoken
kenjiArai	0:d4960fcea8ff	458	)</pre>
kenjiArai	0:d4960fcea8ff	459	*
kenjiArai	0:d4960fcea8ff	460	* <i>Macro</i> to release a semaphore. The semaphore must have previously been
kenjiArai	0:d4960fcea8ff	461	* created with a call to vSemaphoreCreateBinary() or xSemaphoreCreateCounting().
kenjiArai	0:d4960fcea8ff	462	*
kenjiArai	0:d4960fcea8ff	463	* Mutex type semaphores (those created using a call to xSemaphoreCreateMutex())
kenjiArai	0:d4960fcea8ff	464	* must not be used with this macro.
kenjiArai	0:d4960fcea8ff	465	*
kenjiArai	0:d4960fcea8ff	466	* This macro can be used from an ISR.
kenjiArai	0:d4960fcea8ff	467	*
kenjiArai	0:d4960fcea8ff	468	* @param xSemaphore A handle to the semaphore being released. This is the
kenjiArai	0:d4960fcea8ff	469	* handle returned when the semaphore was created.
kenjiArai	0:d4960fcea8ff	470	*
kenjiArai	0:d4960fcea8ff	471	* @param pxHigherPriorityTaskWoken xSemaphoreGiveFromISR() will set
kenjiArai	0:d4960fcea8ff	472	* *pxHigherPriorityTaskWoken to pdTRUE if giving the semaphore caused a task
kenjiArai	0:d4960fcea8ff	473	* to unblock, and the unblocked task has a priority higher than the currently
kenjiArai	0:d4960fcea8ff	474	* running task. If xSemaphoreGiveFromISR() sets this value to pdTRUE then
kenjiArai	0:d4960fcea8ff	475	* a context switch should be requested before the interrupt is exited.
kenjiArai	0:d4960fcea8ff	476	*
kenjiArai	0:d4960fcea8ff	477	* @return pdTRUE if the semaphore was successfully given, otherwise errQUEUE_FULL.
kenjiArai	0:d4960fcea8ff	478	*
kenjiArai	0:d4960fcea8ff	479	* Example usage:
kenjiArai	0:d4960fcea8ff	480	<pre>
kenjiArai	0:d4960fcea8ff	481	\#define LONG_TIME 0xffff
kenjiArai	0:d4960fcea8ff	482	\#define TICKS_TO_WAIT 10
kenjiArai	0:d4960fcea8ff	483	xSemaphoreHandle xSemaphore = NULL;
kenjiArai	0:d4960fcea8ff	484
kenjiArai	0:d4960fcea8ff	485	// Repetitive task.
kenjiArai	0:d4960fcea8ff	486	void vATask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	487	{
kenjiArai	0:d4960fcea8ff	488	for( ;; )
kenjiArai	0:d4960fcea8ff	489	{
kenjiArai	0:d4960fcea8ff	490	// We want this task to run every 10 ticks of a timer. The semaphore
kenjiArai	0:d4960fcea8ff	491	// was created before this task was started.
kenjiArai	0:d4960fcea8ff	492
kenjiArai	0:d4960fcea8ff	493	// Block waiting for the semaphore to become available.
kenjiArai	0:d4960fcea8ff	494	if( xSemaphoreTake( xSemaphore, LONG_TIME ) == pdTRUE )
kenjiArai	0:d4960fcea8ff	495	{
kenjiArai	0:d4960fcea8ff	496	// It is time to execute.
kenjiArai	0:d4960fcea8ff	497
kenjiArai	0:d4960fcea8ff	498	// ...
kenjiArai	0:d4960fcea8ff	499
kenjiArai	0:d4960fcea8ff	500	// We have finished our task. Return to the top of the loop where
kenjiArai	0:d4960fcea8ff	501	// we will block on the semaphore until it is time to execute
kenjiArai	0:d4960fcea8ff	502	// again. Note when using the semaphore for synchronisation with an
kenjiArai	0:d4960fcea8ff	503	// ISR in this manner there is no need to 'give' the semaphore back.
kenjiArai	0:d4960fcea8ff	504	}
kenjiArai	0:d4960fcea8ff	505	}
kenjiArai	0:d4960fcea8ff	506	}
kenjiArai	0:d4960fcea8ff	507
kenjiArai	0:d4960fcea8ff	508	// Timer ISR
kenjiArai	0:d4960fcea8ff	509	void vTimerISR( void * pvParameters )
kenjiArai	0:d4960fcea8ff	510	{
kenjiArai	0:d4960fcea8ff	511	static unsigned char ucLocalTickCount = 0;
kenjiArai	0:d4960fcea8ff	512	static signed portBASE_TYPE xHigherPriorityTaskWoken;
kenjiArai	0:d4960fcea8ff	513
kenjiArai	0:d4960fcea8ff	514	// A timer tick has occurred.
kenjiArai	0:d4960fcea8ff	515
kenjiArai	0:d4960fcea8ff	516	// ... Do other time functions.
kenjiArai	0:d4960fcea8ff	517
kenjiArai	0:d4960fcea8ff	518	// Is it time for vATask () to run?
kenjiArai	0:d4960fcea8ff	519	xHigherPriorityTaskWoken = pdFALSE;
kenjiArai	0:d4960fcea8ff	520	ucLocalTickCount++;
kenjiArai	0:d4960fcea8ff	521	if( ucLocalTickCount >= TICKS_TO_WAIT )
kenjiArai	0:d4960fcea8ff	522	{
kenjiArai	0:d4960fcea8ff	523	// Unblock the task by releasing the semaphore.
kenjiArai	0:d4960fcea8ff	524	xSemaphoreGiveFromISR( xSemaphore, &xHigherPriorityTaskWoken );
kenjiArai	0:d4960fcea8ff	525
kenjiArai	0:d4960fcea8ff	526	// Reset the count so we release the semaphore again in 10 ticks time.
kenjiArai	0:d4960fcea8ff	527	ucLocalTickCount = 0;
kenjiArai	0:d4960fcea8ff	528	}
kenjiArai	0:d4960fcea8ff	529
kenjiArai	0:d4960fcea8ff	530	if( xHigherPriorityTaskWoken != pdFALSE )
kenjiArai	0:d4960fcea8ff	531	{
kenjiArai	0:d4960fcea8ff	532	// We can force a context switch here. Context switching from an
kenjiArai	0:d4960fcea8ff	533	// ISR uses port specific syntax. Check the demo task for your port
kenjiArai	0:d4960fcea8ff	534	// to find the syntax required.
kenjiArai	0:d4960fcea8ff	535	}
kenjiArai	0:d4960fcea8ff	536	}
kenjiArai	0:d4960fcea8ff	537	</pre>
kenjiArai	0:d4960fcea8ff	538	* \defgroup xSemaphoreGiveFromISR xSemaphoreGiveFromISR
kenjiArai	0:d4960fcea8ff	539	* \ingroup Semaphores
kenjiArai	0:d4960fcea8ff	540	*/
kenjiArai	0:d4960fcea8ff	541	#define xSemaphoreGiveFromISR( xSemaphore, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( ( xQueueHandle ) xSemaphore, NULL, pxHigherPriorityTaskWoken, queueSEND_TO_BACK )
kenjiArai	0:d4960fcea8ff	542
kenjiArai	0:d4960fcea8ff	543	/**
kenjiArai	0:d4960fcea8ff	544	* semphr. h
kenjiArai	0:d4960fcea8ff	545	* <pre>xSemaphoreHandle xSemaphoreCreateMutex( void )</pre>
kenjiArai	0:d4960fcea8ff	546	*
kenjiArai	0:d4960fcea8ff	547	* <i>Macro</i> that implements a mutex semaphore by using the existing queue
kenjiArai	0:d4960fcea8ff	548	* mechanism.
kenjiArai	0:d4960fcea8ff	549	*
kenjiArai	0:d4960fcea8ff	550	* Mutexes created using this macro can be accessed using the xSemaphoreTake()
kenjiArai	0:d4960fcea8ff	551	* and xSemaphoreGive() macros. The xSemaphoreTakeRecursive() and
kenjiArai	0:d4960fcea8ff	552	* xSemaphoreGiveRecursive() macros should not be used.
kenjiArai	0:d4960fcea8ff	553	*
kenjiArai	0:d4960fcea8ff	554	* This type of semaphore uses a priority inheritance mechanism so a task
kenjiArai	0:d4960fcea8ff	555	* 'taking' a semaphore MUST ALWAYS 'give' the semaphore back once the
kenjiArai	0:d4960fcea8ff	556	* semaphore it is no longer required.
kenjiArai	0:d4960fcea8ff	557	*
kenjiArai	0:d4960fcea8ff	558	* Mutex type semaphores cannot be used from within interrupt service routines.
kenjiArai	0:d4960fcea8ff	559	*
kenjiArai	0:d4960fcea8ff	560	* See vSemaphoreCreateBinary() for an alternative implementation that can be
kenjiArai	0:d4960fcea8ff	561	* used for pure synchronisation (where one task or interrupt always 'gives' the
kenjiArai	0:d4960fcea8ff	562	* semaphore and another always 'takes' the semaphore) and from within interrupt
kenjiArai	0:d4960fcea8ff	563	* service routines.
kenjiArai	0:d4960fcea8ff	564	*
kenjiArai	0:d4960fcea8ff	565	* @return xSemaphore Handle to the created mutex semaphore. Should be of type
kenjiArai	0:d4960fcea8ff	566	* xSemaphoreHandle.
kenjiArai	0:d4960fcea8ff	567	*
kenjiArai	0:d4960fcea8ff	568	* Example usage:
kenjiArai	0:d4960fcea8ff	569	<pre>
kenjiArai	0:d4960fcea8ff	570	xSemaphoreHandle xSemaphore;
kenjiArai	0:d4960fcea8ff	571
kenjiArai	0:d4960fcea8ff	572	void vATask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	573	{
kenjiArai	0:d4960fcea8ff	574	// Semaphore cannot be used before a call to xSemaphoreCreateMutex().
kenjiArai	0:d4960fcea8ff	575	// This is a macro so pass the variable in directly.
kenjiArai	0:d4960fcea8ff	576	xSemaphore = xSemaphoreCreateMutex();
kenjiArai	0:d4960fcea8ff	577
kenjiArai	0:d4960fcea8ff	578	if( xSemaphore != NULL )
kenjiArai	0:d4960fcea8ff	579	{
kenjiArai	0:d4960fcea8ff	580	// The semaphore was created successfully.
kenjiArai	0:d4960fcea8ff	581	// The semaphore can now be used.
kenjiArai	0:d4960fcea8ff	582	}
kenjiArai	0:d4960fcea8ff	583	}
kenjiArai	0:d4960fcea8ff	584	</pre>
kenjiArai	0:d4960fcea8ff	585	* \defgroup vSemaphoreCreateMutex vSemaphoreCreateMutex
kenjiArai	0:d4960fcea8ff	586	* \ingroup Semaphores
kenjiArai	0:d4960fcea8ff	587	*/
kenjiArai	0:d4960fcea8ff	588	#define xSemaphoreCreateMutex() xQueueCreateMutex()
kenjiArai	0:d4960fcea8ff	589
kenjiArai	0:d4960fcea8ff	590
kenjiArai	0:d4960fcea8ff	591	/**
kenjiArai	0:d4960fcea8ff	592	* semphr. h
kenjiArai	0:d4960fcea8ff	593	* <pre>xSemaphoreHandle xSemaphoreCreateRecursiveMutex( void )</pre>
kenjiArai	0:d4960fcea8ff	594	*
kenjiArai	0:d4960fcea8ff	595	* <i>Macro</i> that implements a recursive mutex by using the existing queue
kenjiArai	0:d4960fcea8ff	596	* mechanism.
kenjiArai	0:d4960fcea8ff	597	*
kenjiArai	0:d4960fcea8ff	598	* Mutexes created using this macro can be accessed using the
kenjiArai	0:d4960fcea8ff	599	* xSemaphoreTakeRecursive() and xSemaphoreGiveRecursive() macros. The
kenjiArai	0:d4960fcea8ff	600	* xSemaphoreTake() and xSemaphoreGive() macros should not be used.
kenjiArai	0:d4960fcea8ff	601	*
kenjiArai	0:d4960fcea8ff	602	* A mutex used recursively can be 'taken' repeatedly by the owner. The mutex
kenjiArai	0:d4960fcea8ff	603	* doesn't become available again until the owner has called
kenjiArai	0:d4960fcea8ff	604	* xSemaphoreGiveRecursive() for each successful 'take' request. For example,
kenjiArai	0:d4960fcea8ff	605	* if a task successfully 'takes' the same mutex 5 times then the mutex will
kenjiArai	0:d4960fcea8ff	606	* not be available to any other task until it has also 'given' the mutex back
kenjiArai	0:d4960fcea8ff	607	* exactly five times.
kenjiArai	0:d4960fcea8ff	608	*
kenjiArai	0:d4960fcea8ff	609	* This type of semaphore uses a priority inheritance mechanism so a task
kenjiArai	0:d4960fcea8ff	610	* 'taking' a semaphore MUST ALWAYS 'give' the semaphore back once the
kenjiArai	0:d4960fcea8ff	611	* semaphore it is no longer required.
kenjiArai	0:d4960fcea8ff	612	*
kenjiArai	0:d4960fcea8ff	613	* Mutex type semaphores cannot be used from within interrupt service routines.
kenjiArai	0:d4960fcea8ff	614	*
kenjiArai	0:d4960fcea8ff	615	* See vSemaphoreCreateBinary() for an alternative implementation that can be
kenjiArai	0:d4960fcea8ff	616	* used for pure synchronisation (where one task or interrupt always 'gives' the
kenjiArai	0:d4960fcea8ff	617	* semaphore and another always 'takes' the semaphore) and from within interrupt
kenjiArai	0:d4960fcea8ff	618	* service routines.
kenjiArai	0:d4960fcea8ff	619	*
kenjiArai	0:d4960fcea8ff	620	* @return xSemaphore Handle to the created mutex semaphore. Should be of type
kenjiArai	0:d4960fcea8ff	621	* xSemaphoreHandle.
kenjiArai	0:d4960fcea8ff	622	*
kenjiArai	0:d4960fcea8ff	623	* Example usage:
kenjiArai	0:d4960fcea8ff	624	<pre>
kenjiArai	0:d4960fcea8ff	625	xSemaphoreHandle xSemaphore;
kenjiArai	0:d4960fcea8ff	626
kenjiArai	0:d4960fcea8ff	627	void vATask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	628	{
kenjiArai	0:d4960fcea8ff	629	// Semaphore cannot be used before a call to xSemaphoreCreateMutex().
kenjiArai	0:d4960fcea8ff	630	// This is a macro so pass the variable in directly.
kenjiArai	0:d4960fcea8ff	631	xSemaphore = xSemaphoreCreateRecursiveMutex();
kenjiArai	0:d4960fcea8ff	632
kenjiArai	0:d4960fcea8ff	633	if( xSemaphore != NULL )
kenjiArai	0:d4960fcea8ff	634	{
kenjiArai	0:d4960fcea8ff	635	// The semaphore was created successfully.
kenjiArai	0:d4960fcea8ff	636	// The semaphore can now be used.
kenjiArai	0:d4960fcea8ff	637	}
kenjiArai	0:d4960fcea8ff	638	}
kenjiArai	0:d4960fcea8ff	639	</pre>
kenjiArai	0:d4960fcea8ff	640	* \defgroup vSemaphoreCreateMutex vSemaphoreCreateMutex
kenjiArai	0:d4960fcea8ff	641	* \ingroup Semaphores
kenjiArai	0:d4960fcea8ff	642	*/
kenjiArai	0:d4960fcea8ff	643	#define xSemaphoreCreateRecursiveMutex() xQueueCreateMutex()
kenjiArai	0:d4960fcea8ff	644
kenjiArai	0:d4960fcea8ff	645	/**
kenjiArai	0:d4960fcea8ff	646	* semphr. h
kenjiArai	0:d4960fcea8ff	647	* <pre>xSemaphoreHandle xSemaphoreCreateCounting( unsigned portBASE_TYPE uxMaxCount, unsigned portBASE_TYPE uxInitialCount )</pre>
kenjiArai	0:d4960fcea8ff	648	*
kenjiArai	0:d4960fcea8ff	649	* <i>Macro</i> that creates a counting semaphore by using the existing
kenjiArai	0:d4960fcea8ff	650	* queue mechanism.
kenjiArai	0:d4960fcea8ff	651	*
kenjiArai	0:d4960fcea8ff	652	* Counting semaphores are typically used for two things:
kenjiArai	0:d4960fcea8ff	653	*
kenjiArai	0:d4960fcea8ff	654	* 1) Counting events.
kenjiArai	0:d4960fcea8ff	655	*
kenjiArai	0:d4960fcea8ff	656	* In this usage scenario an event handler will 'give' a semaphore each time
kenjiArai	0:d4960fcea8ff	657	* an event occurs (incrementing the semaphore count value), and a handler
kenjiArai	0:d4960fcea8ff	658	* task will 'take' a semaphore each time it processes an event
kenjiArai	0:d4960fcea8ff	659	* (decrementing the semaphore count value). The count value is therefore
kenjiArai	0:d4960fcea8ff	660	* the difference between the number of events that have occurred and the
kenjiArai	0:d4960fcea8ff	661	* number that have been processed. In this case it is desirable for the
kenjiArai	0:d4960fcea8ff	662	* initial count value to be zero.
kenjiArai	0:d4960fcea8ff	663	*
kenjiArai	0:d4960fcea8ff	664	* 2) Resource management.
kenjiArai	0:d4960fcea8ff	665	*
kenjiArai	0:d4960fcea8ff	666	* In this usage scenario the count value indicates the number of resources
kenjiArai	0:d4960fcea8ff	667	* available. To obtain control of a resource a task must first obtain a
kenjiArai	0:d4960fcea8ff	668	* semaphore - decrementing the semaphore count value. When the count value
kenjiArai	0:d4960fcea8ff	669	* reaches zero there are no free resources. When a task finishes with the
kenjiArai	0:d4960fcea8ff	670	* resource it 'gives' the semaphore back - incrementing the semaphore count
kenjiArai	0:d4960fcea8ff	671	* value. In this case it is desirable for the initial count value to be
kenjiArai	0:d4960fcea8ff	672	* equal to the maximum count value, indicating that all resources are free.
kenjiArai	0:d4960fcea8ff	673	*
kenjiArai	0:d4960fcea8ff	674	* @param uxMaxCount The maximum count value that can be reached. When the
kenjiArai	0:d4960fcea8ff	675	* semaphore reaches this value it can no longer be 'given'.
kenjiArai	0:d4960fcea8ff	676	*
kenjiArai	0:d4960fcea8ff	677	* @param uxInitialCount The count value assigned to the semaphore when it is
kenjiArai	0:d4960fcea8ff	678	* created.
kenjiArai	0:d4960fcea8ff	679	*
kenjiArai	0:d4960fcea8ff	680	* @return Handle to the created semaphore. Null if the semaphore could not be
kenjiArai	0:d4960fcea8ff	681	* created.
kenjiArai	0:d4960fcea8ff	682	*
kenjiArai	0:d4960fcea8ff	683	* Example usage:
kenjiArai	0:d4960fcea8ff	684	<pre>
kenjiArai	0:d4960fcea8ff	685	xSemaphoreHandle xSemaphore;
kenjiArai	0:d4960fcea8ff	686
kenjiArai	0:d4960fcea8ff	687	void vATask( void * pvParameters )
kenjiArai	0:d4960fcea8ff	688	{
kenjiArai	0:d4960fcea8ff	689	xSemaphoreHandle xSemaphore = NULL;
kenjiArai	0:d4960fcea8ff	690
kenjiArai	0:d4960fcea8ff	691	// Semaphore cannot be used before a call to xSemaphoreCreateCounting().
kenjiArai	0:d4960fcea8ff	692	// The max value to which the semaphore can count should be 10, and the
kenjiArai	0:d4960fcea8ff	693	// initial value assigned to the count should be 0.
kenjiArai	0:d4960fcea8ff	694	xSemaphore = xSemaphoreCreateCounting( 10, 0 );
kenjiArai	0:d4960fcea8ff	695
kenjiArai	0:d4960fcea8ff	696	if( xSemaphore != NULL )
kenjiArai	0:d4960fcea8ff	697	{
kenjiArai	0:d4960fcea8ff	698	// The semaphore was created successfully.
kenjiArai	0:d4960fcea8ff	699	// The semaphore can now be used.
kenjiArai	0:d4960fcea8ff	700	}
kenjiArai	0:d4960fcea8ff	701	}
kenjiArai	0:d4960fcea8ff	702	</pre>
kenjiArai	0:d4960fcea8ff	703	* \defgroup xSemaphoreCreateCounting xSemaphoreCreateCounting
kenjiArai	0:d4960fcea8ff	704	* \ingroup Semaphores
kenjiArai	0:d4960fcea8ff	705	*/
kenjiArai	0:d4960fcea8ff	706	#define xSemaphoreCreateCounting( uxMaxCount, uxInitialCount ) xQueueCreateCountingSemaphore( uxMaxCount, uxInitialCount )
kenjiArai	0:d4960fcea8ff	707
kenjiArai	0:d4960fcea8ff	708
kenjiArai	0:d4960fcea8ff	709	#endif /* SEMAPHORE_H */
kenjiArai	0:d4960fcea8ff	710
kenjiArai	0:d4960fcea8ff	711

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Type:	Program
Created:	01 Jan 2011
Imports:	289
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FreeRTOS/Source/include/semphr.h@0:d4960fcea8ff, 2011-01-01 (annotated)

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