DESCRIPTION

The Semaphores and Message Passing (SMP) Option is a separately licensed option that is available with the XD Ada™ M68000 Family Version 4.0 product on OpenVMS™ Systems. It provides support for two types of inter-task communication: semaphores and message passing.

XD Ada M68000 Family Semaphore Package Features

The XD Ada semaphore package provides support for single processor semaphore operations. Semaphores are commonly used in conjunction with tasking to control the interactions among and between multiple tasks and shared resources.

Three types of semaphore are provided to support a wide range of user applications, including the classic producer/consumer problems using bounded buffers, as follows:

· General Semaphore

· Counting Semaphore

· Binary Semaphore

The following semaphore operations are supported:

· WAIT — if the semaphore is raised, decrement the value of the semaphore, else suspend the task. Conditional and timed wait operations are also supported.

· SIGNAL — if a task is suspended at the semaphore then resume the task, else increment the semaphore. The signal operation from within an interrupt handler is also supported.

XD Ada M68000 Family Message Passing Features

The XD Ada message passing package allows application program tasks to synchronize and communicate with each other by sending and receiving messages to and from mailboxes. Messages may be passed both between tasks running on the same processor (i.e. tasks in the same Ada program) and also between tasks running on different processors in tightly coupled multiprocessor systems (i.e. systems in which processors communicate using shared memory and interprocessor interrupts).

The following gives a summary of the message passing operations supported:

· CREATE—creates a new mailbox for intraprocessor or interprocessor messages.

· SEND — sends a message to a specified mailbox; if the mailbox is full then the calling task is suspended until a message slot becomes available in that mailbox. Conditional and timed send operations are also supported.

· RECEIVE — receives a message from a specified mailbox; if the mailbox is empty then the calling task is suspended until a message becomes available in that mailbox. Conditional and timed receive operations are also supported.

· EXPORT — makes a mailbox accessible to all Ada programs in a system.

· IMPORT — makes an exported mailbox visible in the calling program.

Software Components

The software for XD Ada M68000 Family Semaphores and Message Passing Version 4.0 for OpenVMS Systems consists of the following:

· Additional Ada predefined units for Semaphore Package and Message Passing that are compiled into the Ada predefined library.

· Example configuration of multiprocessor message passing for a three processor MVME135-1 system.

The software is supplied in source form so that the message passing package can be reconfigured for other target configurations based on M68000 family processors including the CPU32.

Documentation

Details of the Semaphores and Message Passing Option are documented in the manuals supplied with the XD Ada M68000 Family Version 4.0 product. Instructions for installing the XD Ada Semaphores and Message Passing Option are detailed in the XD Ada M68000 Family Installation Guide for OpenVMS Systems.

TARGET HARDWARE REQUIREMENTS

The use of single-processor message passing imposes no special requirements on the target hardware.

The use of multiprocessor message passing requires that the target boards provide shared memory and the ability for any board to individually interrupt any other specific board.

These requirements may not be fulfilled by all Motorola M68000 family boards. For example, they are fulfilled by the MVME135 board, but the MVME133XT board has limited interprocessor interrupt facilities with the result that it can only sensibly be used in a two-board multiprocessor configuration for message passing. For this reason, the product includes an example configuration for the MVME135.

HOST SOFTWARE REQUIREMENTS

The host software requirements are listed in the XD Ada M68000 Family for OpenVMS Integrity Servers^TM Version 4.0 Software Product Description and XD Ada M68000 Family for OpenVMS AXP Systems Version 4.0 Software Product Description.

ORDERING INFORMATION

For information on how to order this product option, contact your local Sales Office.

SOFTWARE LICENSING

This software is furnished under the provisions of a software licence.

Licenses for educational institutions are available.

For more information on licensing terms and conditions, contact your local Sales Office.

SOFTWARE WARRANTY

Warranty for this product is provided in accordance with the terms and conditions of the license.

The above information is valid at time of release. Please contact your local Sales Office for the latest information.

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