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Buses and Atomic Subsystems

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Extract Nonvirtual Bus Signals Inside of Atomic Subsystems Virtual Bus Signals Crossing Atomic Boundaries Atomic Subsystems and Buses of Constants

Extract Nonvirtual Bus Signals Inside of Atomic Subsystems

Selecting signals from of a nonvirtual bus can result in unnecessary data copies when those signals cross an atomic boundary. In the following example the same code, a simple multiplication of two elements in a vector, is executed three times:

In the second instance when the bus signals are selected outside of the atomic subsystem an unnecessary copy of the bus data is created:

Although this example shows only signals with global scope, both global and local signals show the same behavior: the selection of the signals outside of the model results in an unnecessary copy, while the internal selection does not.

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Virtual Bus Signals Crossing Atomic Boundaries

Virtual buses that cross atomic boundaries can result in the creation of unnecessary data copies. The following example shows the data copy that occurs when a virtual bus crosses an atomic boundary:

Lines 25–26 show the signals being selected out of the bus before they are used in the function on lines 19–20. By comparison the nonvirtual bus does not require the use of temporary variables.

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Atomic Subsystems and Buses of Constants

If the bus passed into an atomic subsystem consists exclusively of constants, using a virtual bus is more efficient, because Simulink is able to inline the constant values into the code:

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Setting Bus Signal Initial Values

Renaming and Replacing Data Types

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