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VDK Message Passing

6-4 Getting Started with ADSP-BF548 EZ-KIT Lite

It is possible to use the two complementary features (VDK’s higher-level

device model and the SSL/device drivers’ low-level code) together in one

application, as shown in example 7.

VDK Message Passing

As mentioned before, VDK supports a variety of inter-thread synchroniza-

tion methods. For example, two different threads in your application may

require access to the same shared resource; for example, a data buffer. In

this case, a semaphore or mutex can be used to protect the resource against

concurrent accesses. Or, your application takes the form of a control

thread that creates data for worker threads to process and requires a syn-

chronized access to a queue of work requests (messages). VDK provides

such a mechanism: the required message queues are defined at project cre-

ation and created during application start-up. VDK automatically

coordinates the flow of messages in to and out from the queue as the

application executes.

Example 7 uses VDK messages to pass information about keypad presses

from the boot thread to a worker thread.

Introductory and reference material about VDK can be found in the Visu-

alDSP++ Kernel (VDK) User’s Guide that is part of the VisualDSP++

online help under Manuals–>Software Tools Manuals.

Example 7: Creating a VDK Application

Example 7 was created as a VDK project by selecting the project type

VDK application on the initial page of the New Project wizard. When-

ever VisualDSP++ creates a new VDK project or opens an existing one, a

new tab labelled Kernel is created in the Project window. The Kernel tab

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HP EZ-KIT Manual de usuario Pagina 88