interface xdc.runtime.knl.ISemProcessSupport
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Interface for OS specific back-end

The xdc.runtime.knl package contains modules that provide typical OS services. These xdc.runtime.knl modules however require proxies to be bound to an OS specific delegate. This specifies the interface to be implemented by the OS specific delegate for xdc.runtime.knl.SemProcess module. [ more ... ]
XDCspec summary sourced in xdc/runtime/knl/ISemProcessSupport.xdc
interface ISemProcessSupport {  ...
// inherits xdc.runtime.knl.ISemaphore
    // inherits xdc.runtime.IModule
instance:  ...
XDCspec declarations sourced in xdc/runtime/knl/ISemProcessSupport.xdc
package xdc.runtime.knl;
 
interface ISemProcessSupport inherits ISemaphore {
module-wide constants & types
    const UInt FOREVER// Used as the timeout value to specify wait forever = ~(0);
    enum Mode// Types of semaphores {
        Mode_COUNTING// Counting semaphore,
        Mode_BINARY// Binary Semaphore
    };
    enum PendStatus// Error codes returned by Semaphore_pend {
        PendStatus_ERROR,
        PendStatus_TIMEOUT,
        PendStatus_SUCCESS
    };
module-wide config parameters
    metaonly config Types.Common$ common$// Common module configuration parameters;
 
instance:
per-instance config parameters
    config ISemaphore.Mode mode// Semaphore mode. Default is COUNTING = ISemaphore.Mode_COUNTING;
per-instance creation
    create// Create an instance-object(Int count, Int key);
per-instance functions
    Int pend// Wait for the semaphore to become available(UInt timeout, Error.Block *eb);
    Bool post// Increment the semaphore count(Error.Block *eb);
}
DETAILS
The xdc.runtime.knl package contains modules that provide typical OS services. These xdc.runtime.knl modules however require proxies to be bound to an OS specific delegate. This specifies the interface to be implemented by the OS specific delegate for xdc.runtime.knl.SemProcess module.
create() takes a 32-bit integer key parameter to be used for identifying the semaphore to create across processes. For example, for Linux System V semaphores, the key is necessary so that different processes can access the same semaphore.
const ISemProcessSupport.FOREVER
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Used as the timeout value to specify wait forever

XDCspec declarations sourced in xdc/runtime/knl/ISemProcessSupport.xdc
const UInt FOREVER = ~(0);
enum ISemProcessSupport.Mode
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Types of semaphores

XDCspec declarations sourced in xdc/runtime/knl/ISemProcessSupport.xdc
enum Mode {
    Mode_COUNTING,
    // Counting semaphore
    Mode_BINARY
    // Binary Semaphore
};
enum ISemProcessSupport.PendStatus
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Error codes returned by Semaphore_pend

XDCspec declarations sourced in xdc/runtime/knl/ISemProcessSupport.xdc
enum PendStatus {
    PendStatus_ERROR,
    PendStatus_TIMEOUT,
    PendStatus_SUCCESS
};
metaonly config ISemProcessSupport.common$  // module-wide
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Common module configuration parameters

XDCspec declarations sourced in xdc/runtime/knl/ISemProcessSupport.xdc
metaonly config Types.Common$ common$;
DETAILS
All modules have this configuration parameter. Its name contains the '$' 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.
config ISemProcessSupport.mode  // instance
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Semaphore mode. Default is COUNTING

XDCspec declarations sourced in xdc/runtime/knl/ISemProcessSupport.xdc
config ISemaphore.Mode mode = ISemaphore.Mode_COUNTING;
DETAILS
When mode is BINARY , the semaphore has only two states, available and unavailable. When mode is COUNTING, the semaphore keeps track of number of times a semaphore is posted.
Instance Creation
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XDCspec declarations sourced in xdc/runtime/knl/ISemProcessSupport.xdc
create(Int count, Int key);
// Create an instance-object
ARGUMENTS
count — initial semaphore count
key — globally unique key
DETAILS
This function creates a new SemProcess object which is initialized to count. All semaphores created with the same key reference the same underlying synchronization object and work between processes. The underlying synchronization object should be automatically deleted when all references to it have been deleted, and the reference count should be maintained consistently across process forks or similar operations. An implementation for a platform on which this is technically impossible (e.g. an operating system that does not support multiple processes) may provide a 'toy' implementation with behavior matching that of ISemProcessSupport.
ISemProcessSupport.pend()  // instance
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Wait for the semaphore to become available

XDCspec declarations sourced in xdc/runtime/knl/ISemProcessSupport.xdc
Int pend(UInt timeout, Error.Block *eb);
ARGUMENTS
timeout — timeout in microseconds
eb — error block
DETAILS
RETURNS
refer to description above
ISemProcessSupport.post()  // instance
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Increment the semaphore count

XDCspec declarations sourced in xdc/runtime/knl/ISemProcessSupport.xdc
Bool post(Error.Block *eb);
ARGUMENTS
eb — error block
RETURNS
true for success, false for error in error block
generated on Tue, 24 Aug 2010 15:39:32 GMT