IAR PowerPac RTOS User Guide

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Additional InformationIf the counter of the semaphore is not 0, the counter is decremented and program execution continues. If the counter is0, WaitCSemaTimed() waits until the semaphore is signaled by another task, a timer, or an interrupt handler via a callto OS_SignalCSema(). The counter is then decremented and program execution continues. If the semaphore was notsignaled within the specified time, the program execution continues but returns a value of 0. An unlimited number oftasks can wait for a semaphore. According to the rules of the scheduler, of all the tasks waiting for the semaphore, thetask with the highest priority will continue program execution.ImportantThis function may not be called from within an interrupt handler.OS_CSemaRequest()DescriptionDecrements the counter of a semaphore, if it is signaled.Prototypechar OS_CSemaRequest (OS_CSEMA* pCSema);ParameterDescriptionpCSemaPointer to a data structure of type OS_CSEMA.Table 55: OS_GetCSemaRequest() parameter listReturn value0: Failed, semaphore was not signaled.1: OK, semaphore was available and counter was decremented once.Additional informationIf the counter of the semaphore is not 0, the counter is decremented and program execution continues. If the counter is0, OS_CSemaRequest() does not wait and does not modify the semaphore counter. The function returns with errorstate. Because this function never blocks a calling task, this function may be called from an interrupt handler.OS_GetCSemaValue()DescriptionReturns the counter value of a specified semaphore.Prototypeint OS_GetCSemaValue (OS_SEMA* pCSema);ParameterDescriptionpCSemaTable 56: OS_GetCSemaValue() parameter listReturn valueThe counter value of the semaphore.OS_SetCSemaValue()DescriptionSets the counter value of a specified semaphore.PrototypePointer to a data structure of type OS_CSEMA.int OS_SetCSemaValue (OS_SEMA* pCSema,OS_UINT Value);ParameterDescriptionpCSemaTable 57: OS_SetCSemaValue() parameter listPointer to a data structure of type OS_CSEMA.58IAR PowerPac RTOSfor ARM CoresPPRTOS-2
Counting SemaphoresReturn value0: If the value could be set.!= 0: In case of error.OS_DeleteCSema()DescriptionReturns the counter value of a specified semaphore.Prototypevoid OS_DeleteCSema (OS_CSEMA* pCSema);ParameterDescriptionpCSemaTable 58: OS_DeleteCSema() parameter listAdditional InformationPointer to a data structure of type OS_CSEMA.Before deleting a semaphore, make sure that no task is waiting for it and that no task will signal that semaphore at alater point.The debug version of IAR PowerPac RTOS will reflect an error if a deleted semaphore is signaled.PPRTOS-259
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IAR PowerPac RTOSUser GuidePPRTOS-2
Page 3 and 4:
PrefaceWelcome to the IAR PowerPac
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ContentsPreface ...................
Page 7 and 8: ContentsOS_WaitCSema() ............
Page 9 and 10: ContentsOS_LeaveInterrupt() .......
Page 11 and 12: Introduction to IAR PowerPacRTOSWha
Page 13 and 14: Basic conceptsTasksIn this context,
Page 15 and 16: Basic conceptsPREEMPTIVES MULTITASK
Page 17 and 18: Basic conceptsMAILBOXES AND QUEUESA
Page 19 and 20: Basic conceptsThe active task may b
Page 21 and 22: Basic conceptsThe flowchart below i
Page 23 and 24: Basic conceptsLIST OF LIBRARIESIn y
Page 25 and 26: Task routinesIntroductionA task tha
Page 27 and 28: Task routinesOS_CREATETASK() can be
Page 29 and 30: Task routinesExampleThe following e
Page 31 and 32: Task routinesExampleint sec,min;voi
Page 33 and 34: Task routinesAdditional Information
Page 35 and 36: Task routinesReturn valueOS_TASKID:
Page 37 and 38: Software timersSoftware timerA soft
Page 39 and 40: Software timers#define OS_CREATETIM
Page 41 and 42: Software timersOS_SetTimerPeriod()D
Page 43 and 44: Software timersAdditional Informati
Page 45 and 46: Software timersAdditional Informati
Page 47 and 48: Software timersExampleOS_TIMER TIME
Page 49 and 50: Resource semaphoresIntroductionReso
Page 51 and 52: Resource semaphoresResource semapho
Page 53 and 54: Resource semaphoresOS_Request()Desc
Page 55 and 56: Counting SemaphoresIntroductionCoun
Page 57: Counting SemaphoresPrototypevoid OS
Page 61 and 62: MailboxesWhy mailboxes?In the prece
Page 63 and 64: MailboxesMailboxes API function ove
Page 65 and 66: MailboxesExampleSingle-byte mailbox
Page 67 and 68: MailboxesPrototypevoid OS_GetMail (
Page 69 and 70: MailboxesOS_WaitMail()DescriptionWa
Page 71 and 72: QueuesWhy queues?In the preceding c
Page 73 and 74: QueuesReturn valueThe size of the r
Page 75 and 76: QueuesExamplestatic void MemoryTask
Page 77 and 78: Task eventsIntroductionTask events
Page 79 and 80: Task eventsExampleOS_WaitEventTimed
Page 81 and 82: Task eventsPrototypechar OS_ClearEv
Page 83 and 84: Event objectsIntroductionEvent obje
Page 85 and 86: Event objectsExampleif (OS_EVENT_Wa
Page 87 and 88: Event objectsExampleOS_EVENT_Reset(
Page 89 and 90: Heap type memory managementANSI C o
Page 91 and 92: Fixed block size memory poolsIntrod
Page 93 and 94: Fixed block size memory poolsProtot
Page 95 and 96: Fixed block size memory poolsProtot
Page 97 and 98: StacksIntroductionThe stack is the
Page 99 and 100: InterruptsIntroductionIn this chapt
Page 101 and 102: InterruptsRules for interrupt handl
Page 103 and 104: InterruptsOS_LeaveInterruptNoSwitch
Page 105 and 106: InterruptsNesting interrupt routine
Page 107 and 108: Critical RegionsIntroductionCritica
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System variablesIntroductionThe sys
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Configuration for your targetsystem
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Time measurementIntroductionIAR Pow
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Time measurementPrototypeU32 OS_Get
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Time measurementPrototypeOS_U32 OS_
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RTOS-aware debuggingThis chapter de
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RTOS-aware debuggingTimersA softwar
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DebuggingRuntime errorsSome error c
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DebuggingValue Define Description17
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Performance and resource usageThis
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Performance and resource usageThe c
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Performance and resource usage*/sta
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ReentranceAll routines that can be
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LimitationsThe following limitation
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Source code of kernel and libraryIn
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Additional modulesKeyboard manager:
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FAQ (frequently asked questions)Q:
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GlossaryActive TaskCooperativemulti
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IndexIndexAAdditional modules . . .
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IndexOS_WaitSingleEventTimed(). . .
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IAR PowerPac RTOS User Guide

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