Page Comparison

.NamePtr

This is a pointer to an ASCII string used to provide a name to the mutual exclusion semaphore. The ASCII string can have any length as long as it is NUL terminated.

.PendList.NbrEntries

Each mutual exclusion semaphore contains a list of tasks waiting for the semaphore to be released. The variable represents the number of entries in the wait list.

.OwnerOriginalPrio

This variable holds the original priority of the task that owns the mutual exclusion semaphore.

.OwnerTCBPtr->Prio

Dereferencing the pointer to the OS_TCB of the mutual exclusion semaphore owner allows the application to determine whether a task priority was changed.

.OwnerNestingCtr

This variable indicates how many times the owner of the mutual exclusion semaphore requested the semaphore.

.TS

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Mutual Exclusion Semaphores

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Table C-11 shows the difference in API for mutual exclusion semaphore management.

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HTML Table

summary
class	Plain_Table

Table Row (tr)

Table Cell (td)

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	1089777

µC/OS-II (os_mutex.c)

Table Cell (td)

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	1089779
	1089779

µC/OS-III (os_mutex.c)

Table Cell (td)

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	1089781
	1089781

Note

Table Row (tr)

Table Cell (td)

rowspan	5

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	1089783
	1089783

BOOLEAN

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	1089789

OSMutexAccept(

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	1089795
	1089795

OS_EVENT *pevent,

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	1089801
	1089801

INT8U *perr);

Table Cell (td)

rowspan	5

Anchor

	1089785
	1089785

Table Cell (td)

rowspan	5

Anchor

	1089811
	1089811

(1)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Cell (td)

rowspan	5

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	1089813
	1089813

OS_EVENT *

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	1089819

OSMutexCreate(

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INT8U prio,

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	1089831
	1089831

INT8U *perr);

Table Cell (td)

rowspan	5

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	1090203
	1090203

void

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	1090204

OSMutexCreate(

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	1090205
	1090205

OS_MUTEX *p_mutex,

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	1090206
	1090206

CPU_CHAR *p_name,

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	1090207
	1090207

OS_ERR *p_err);

Table Cell (td)

rowspan	5

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	1090209
	1090209

(2)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Cell (td)

rowspan	6

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	1089873
	1089873

OS_EVENT *

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	1089879
	1089879

OSMutexDel(

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	1089885

OS_EVENT *pevent,

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	1089891
	1089891

INT8U opt,

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	1089897

INT8U *perr);

Table Cell (td)

rowspan	6

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	1089905

void

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	1090238

OSMutexDel(

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	1090239

OS_MUTEX *p_mutex,

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	1090240
	1090240

OS_OPT opt,

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	1090230

OS_ERR *p_err);

Table Cell (td)

rowspan	6

Anchor

	1089877
	1089877

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Cell (td)

rowspan	6

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	1089939
	1089939

void

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	1089945

OSMutexPend(

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	1089951
	1089951

OS_EVENT *pevent,

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	1089957
	1089957

INT32U timeout,

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	1089963
	1089963

INT8U *perr);

Table Cell (td)

rowspan	6

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	1090272

void

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OSMutexPend(

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OS_MUTEX *p_mutex,

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	1090275
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OS_TICK timeout,

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	1090276
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OS_OPT opt,

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CPU_TS *p_ts,

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	1090278

OS_ERR *p_err);

Table Cell (td)

rowspan	6

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(3)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Cell (td)

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Table Cell (td)

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	1090019

OS_OBJ_QTY

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OSMutexPendAbort(

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OS_MUTEX *p_mutex,

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OS_OPT opt,

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OS_ERR *p_err);

Table Cell (td)

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	1090021

Table Row (tr)

Table Cell (td)

rowspan	4

Anchor

	1090053
	1090053

INT8U

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	1090059

OSMutexPost(

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	1090065
	1090065

OS_EVENT *pevent);

Table Cell (td)

rowspan	4

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	1090073

void

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OSMutexPost(

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OS_MUTEX *p_mutex,

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	1090356
	1090356

OS_OPT opt,

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OS_ERR *p_err);

Table Cell (td)

rowspan	4

Anchor

	1090057
	1090057

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Row (tr)

Table Cell (td)

rowspan	4

Anchor

	1090107
	1090107

INT8U

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	1090113
	1090113

OSMutexQuery(

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	1090119
	1090119

OS_EVENT *pevent,

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	1090125
	1090125

OS_MUTEX_DATA *p_mutex_data);

Table Cell (td)

rowspan	4

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	1090109

Table Cell (td)

rowspan	4

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	1090111

(4)

Table Row (tr)

Table Row (tr)

Table Row (tr)

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1. Anchor
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  Mutual Exclusion Semaphore Management API
  1. Anchor
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    In µC/OS-III, there is no “accept” API, since this feature is built into the OSMutexPend() by specifying the OS_OPT_PEND_NON_BLOCKING option.
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    In µC/OS-II, OSMutexCreate() returns the address of an OS_EVENT, which is used as the “handle” to the message mailbox. In µC/OS-III, the application must allocate storage for an OS_MUTEX, which serves the same purpose as the OS_EVENT. The benefit in µC/OS-III is that it is not necessary to predetermine the number of mutual-exclusion semaphores at compile time.
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    µC/OS-III returns additional information when a mutex is released. The releaser takes a snapshot of the current time stamp and stores it in the OS_MUTEX. The new owner of the mutex therefore knows when the mutex was released.
  4. Anchor
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    µC/OS-III does not provide query services as they were rarely used.

Versions Compared

Old Version 2

New Version 3

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