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Semaphore Class Reference
Public Member Functions | Private Member Functions

Semaphore Class Reference
[Semaphore class]

The Semaphore class is used to manage and protect access to a set of shared resources. More...

#include <Semaphore.h>

Inherits NonCopyable< Semaphore >.

Public Member Functions

 Semaphore (int32_t count=0)
 Create and Initialize a Semaphore object used for managing resources.
 Semaphore (int32_t count, uint16_t max_count)
 Create and Initialize a Semaphore object used for managing resources.
int32_t wait (uint32_t millisec=osWaitForever)
 Wait until a Semaphore resource becomes available.
int32_t wait_until (uint64_t millisec)
 Wait until a Semaphore resource becomes available.
osStatus release (void)
 Release a Semaphore resource that was obtain with Semaphore::wait.
 ~Semaphore ()
 Semaphore destructor.

Private Member Functions

 MBED_DEPRECATED ("Invalid copy construction of a NonCopyable resource.") NonCopyable(const NonCopyable &)
 NonCopyable copy constructor.
 MBED_DEPRECATED ("Invalid copy assignment of a NonCopyable resource.") NonCopyable &operator
 NonCopyable copy assignment operator.

Detailed Description

The Semaphore class is used to manage and protect access to a set of shared resources.

Note:
Memory considerations: The semaphore control structures will be created on current thread's stack, both for the mbed OS and underlying RTOS objects (static or dynamic RTOS memory pools are not being used).

Definition at line 45 of file Semaphore.h.

Constructor & Destructor Documentation

Semaphore ( int32_t  count = 0 )

Create and Initialize a Semaphore object used for managing resources.

Parameters:
countnumber of available resources; maximum index value is (count-1). (default: 0).
Note:
You cannot call this function from ISR context.

Definition at line 22 of file Semaphore_stub.cpp.

Semaphore ( int32_t  count,
uint16_t  max_count 
)

Create and Initialize a Semaphore object used for managing resources.

Parameters:
countnumber of available resources
max_countmaximum number of available resources
Note:
You cannot call this function from ISR context.

Definition at line 27 of file Semaphore_stub.cpp.

~Semaphore (  )

Semaphore destructor.

Note:
You cannot call this function from ISR context.

Definition at line 52 of file Semaphore_stub.cpp.

Member Function Documentation

osStatus release ( void   )

Release a Semaphore resource that was obtain with Semaphore::wait.

Returns:
status code that indicates the execution status of the function: osOK the token has been correctly released. osErrorResource the maximum token count has been reached. osErrorParameter internal error.
Note:
You may call this function from ISR context.

Definition at line 47 of file Semaphore_stub.cpp.

int32_t wait ( uint32_t  millisec = osWaitForever )

Wait until a Semaphore resource becomes available.

Parameters:
millisectimeout value or 0 in case of no time-out. (default: osWaitForever).
Returns:
number of available tokens, before taking one; or -1 in case of incorrect parameters
Note:
You may call this function from ISR context if the millisec parameter is set to 0.

Definition at line 37 of file Semaphore_stub.cpp.

int32_t wait_until ( uint64_t  millisec )

Wait until a Semaphore resource becomes available.

Parameters:
millisecabsolute timeout time, referenced to Kernel::get_ms_count()
Returns:
number of available tokens, before taking one; or -1 in case of incorrect parameters
Note:
the underlying RTOS may have a limit to the maximum wait time due to internal 32-bit computations, but this is guaranteed to work if the wait is <= 0x7fffffff milliseconds (~24 days). If the limit is exceeded, the acquire attempt will time out earlier than specified.
You cannot call this function from ISR context.

Definition at line 42 of file Semaphore_stub.cpp.

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