GateMutexPri is a mutex gate (it can only be held by one thread at a time)
which implements priority inheritance in order to prevent priority
inversion. Priority inversion occurs when a high priority task has its
priority effectively 'inverted' because it is waiting on a gate held by a
low priority task.
When multiple tasks wait on this gate, they will receive the gate in order
of priority (higher priority tasks will receive the gate first). This is
because the queue of tasks waiting on a GateMutexPri is sorted by priority,
not FIFO.
const GateMutexPri_Q_BLOCKING |
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Blocking quality
#define GateMutexPri_Q_BLOCKING (Int)1
DETAILS
Gates with this "quality" may cause the calling thread to block;
i.e., suspend execution until another thread leaves the gate.
const GateMutexPri_Q_PREEMPTING |
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Preempting quality
#define GateMutexPri_Q_PREEMPTING (Int)2
DETAILS
Gates with this "quality" allow other threads to preempt the thread
that has already entered the gate.
config GateMutexPri_A_badContext // module-wide |
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Assert when GateMutexPri_enter() is not called from correct context.
GateMutexPri_enter() can only be called from main() or Task context (not
Hwi or Swi)
extern const Assert_Id GateMutexPri_A_badContext;
DETAILS
Common causes and workarounds for hitting this Assert:
- Calling printf() from a Hwi or Swi thread.
- Use xdc.runtime.System_printf (with SysMin) instead.
- Calling System_printf() from a Hwi or Swi thread when using SysStd.
- Calling Memory_alloc() from a Hwi or Swi thread.
- Use a different Heap manager
config GateMutexPri_A_enterTaskDisabled // module-wide |
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Asserted in GateMutexPri_enter()
extern const Assert_Id GateMutexPri_A_enterTaskDisabled;
DETAILS
Assert raised if GateMutexPri_enter() is called with the Task or
Swi scheduler disabled.
GateMutexPri_query() // module-wide |
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Runtime test for a particular gate quality
Bool GateMutexPri_query(Int qual);
ARGUMENTS
qual
constant describing a quality
RETURNS
Returns TRUE if the gate has the given quality,
and FALSE otherwise, which includes the case when the gate does not
recognize the constant describing the quality.
Module-Wide Built-Ins |
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// Get this module's unique id
Bool GateMutexPri_Module_startupDone();
// Test if this module has completed startup
// The heap from which this module allocates memory
Bool GateMutexPri_Module_hasMask();
// Test whether this module has a diagnostics mask
Bits16 GateMutexPri_Module_getMask();
// Returns the diagnostics mask for this module
Void GateMutexPri_Module_setMask(Bits16 mask);
// Set the diagnostics mask for this module
Instance Object Types |
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typedef struct GateMutexPri_Object GateMutexPri_Object;
// Opaque internal representation of an instance object
// Client reference to an instance object
typedef struct GateMutexPri_Struct GateMutexPri_Struct;
// Opaque client structure large enough to hold an instance object
// Convert this instance structure pointer into an instance handle
// Convert this instance handle into an instance structure pointer
Instance Config Parameters |
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typedef struct GateMutexPri_Params {
// Instance config-params structure
// Common per-instance configs
} GateMutexPri_Params;
// Initialize this config-params structure with supplier-specified defaults before instance creation
Runtime Instance Creation |
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// Allocate and initialize a new instance object and return its handle
// Initialize a new instance object inside the provided structure
ARGUMENTS
params
per-instance config params, or NULL to select default values (target-domain only)
eb
active error-handling block, or NULL to select default policy (target-domain only)
Instance Deletion |
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// Finalize and free this previously allocated instance object, setting the referenced handle to NULL
// Finalize the instance object inside the provided structure
GateMutexPri_enter() // instance |
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Enter this gate
ARGUMENTS
handle
handle of a previously-created GateMutexPri instance object
DETAILS
Each gate provider can implement mutual exclusion using different
algorithms; e.g., disabling all scheduling, disabling the scheduling
of all threads below a specified "priority level", suspending the
caller when the gate has been entered by another thread and
re-enabling it when the the other thread leaves the gate. However,
in all cases, after this method returns that caller has exclusive
access to the data protected by this gate.
A thread may reenter a gate without blocking or failing.
RETURNS
Returns a "key" that is used to
leave this gate; this
value is used to restore thread preemption to the state that
existed just prior to entering this gate.
GateMutexPri_leave() // instance |
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Leave this gate
ARGUMENTS
handle
handle of a previously-created GateMutexPri instance object
key
the value returned by a matching call to
enter
DETAILS
This method is only called by threads that have previously entered
this gate via
enter. After this method returns, the
caller must not access the data structure protected by this gate
(unless the caller has entered the gate more than once and other
calls to
leave remain to balance the number of previous
calls to
enter).
Instance Convertors |
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// unconditionally move one level up the inheritance hierarchy
// conditionally move one level down the inheritance hierarchy; NULL upon failure
Instance Built-Ins |
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Int GateMutexPri_Object_count();
// The number of statically-created instance objects
// The handle of the i-th statically-created instance object (array == NULL)
// The handle of the first dynamically-created instance object, or NULL
// The handle of the next dynamically-created instance object, or NULL
// The heap used to allocate dynamically-created instance objects
// The label associated with this instance object
// The name of this instance object
const GateMutexPri.Q_BLOCKING |
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Blocking quality
const GateMutexPri.Q_BLOCKING = 1;
DETAILS
Gates with this "quality" may cause the calling thread to block;
i.e., suspend execution until another thread leaves the gate.
C SYNOPSIS
const GateMutexPri.Q_PREEMPTING |
|
Preempting quality
const GateMutexPri.Q_PREEMPTING = 2;
DETAILS
Gates with this "quality" allow other threads to preempt the thread
that has already entered the gate.
C SYNOPSIS
config GateMutexPri.A_badContext // module-wide |
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Assert when GateMutexPri_enter() is not called from correct context.
GateMutexPri_enter() can only be called from main() or Task context (not
Hwi or Swi)
msg: "A_badContext: bad calling context. See GateMutexPri API doc for details."
};
DETAILS
Common causes and workarounds for hitting this Assert:
- Calling printf() from a Hwi or Swi thread.
- Use xdc.runtime.System_printf (with SysMin) instead.
- Calling System_printf() from a Hwi or Swi thread when using SysStd.
- Calling Memory_alloc() from a Hwi or Swi thread.
- Use a different Heap manager
C SYNOPSIS
config GateMutexPri.A_enterTaskDisabled // module-wide |
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Asserted in GateMutexPri_enter()
msg: "A_enterTaskDisabled: Cannot call GateMutexPri_enter() while the Task or Swi scheduler is disabled."
};
DETAILS
Assert raised if GateMutexPri_enter() is called with the Task or
Swi scheduler disabled.
C SYNOPSIS
metaonly config GateMutexPri.common$ // module-wide |
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Common module configuration parameters
DETAILS
All modules have this configuration parameter. Its name
contains the '$' character to ensure it does not conflict with
configuration parameters declared by the module. This allows
new configuration parameters to be added in the future without
any chance of breaking existing modules.
metaonly GateMutexPri.queryMeta() // module-wide |
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Configuration time test for a particular gate quality
GateMutexPri.queryMeta(Int qual) returns Bool
ARGUMENTS
qual
constant describing a quality
RETURNS
Returns TRUE if the gate has the given quality,
and FALSE otherwise, which includes the case when the gate does not
recognize the constant describing the quality.
Instance Config Parameters |
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var params = new GateMutexPri.Params;
// Instance config-params object
Static Instance Creation |
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var params =
new GateMutexPri.
Params;
// Allocate instance config-params
params.config = ...
// Assign individual configs
var inst = GateMutexPri.create(params);
// Create an instance-object
ARGUMENTS
params
per-instance config params, or NULL to select default values (target-domain only)
eb
active error-handling block, or NULL to select default policy (target-domain only)