INtime® 3.1 Software - tenAsys

INtime 3.1 Software
RT calls
You use these calls when developing the real-time portion of an INtime application.
High-level (validating) calls
High-level calls provide higher protection and validation features. Memory is allocated
automatically from the process’s pool. Each high level object consumes a slot from the
system GDT (8000 objects maximum)
High-level system calls validate a call’s parameters; a condition code returned by the
call indicates whether you used invalid parameters. Condition codes for trying to read
or write memory to which you have no access also exist.
High-level exchange objects validate parameters and are protected against unexpected
deletion. High-level calls exist for these exchange objects:
• Object and data mailboxes
• Counting semaphores
• Regions (for mutual exclusion with priority inversion protection)
Low-level (non-validating) calls
Low-level calls provide higher performance, but lower protection and validation
features. Low-level objects provide functionality beyond that of high-level objects.
You must allocate memory for low-level objects and may allocate memory beyond lowlevel
object needs. You can use this additional memory to store application-specific
state information associated with the object.
Low-level objects are not protected against unexpected deletion and do not validate
parameters (if you need parameter validation, use high-level system calls). Low-level
calls use the flat, 4 Gbyte addressing capabilities of the microprocessor. They do not
use segmentation. Therefore, they do not consume a slot from the system GDT.
Use low-level objects in these situations:
• For isolated parts of the application, such as signaling ordinary threads from an
interrupt handler.
• When performance is critical, such as high-performance, unvalidated sending and
receiving of data mailbox messages and semaphore units.
Note
System calls that manipulate low-level objects assume that all memory reference pointers
received are valid.
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