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3 Code generation

3.1 TargetLink

TargetLink makes it easy to generate code since everything related to the code

generation is gathered in one place. It is one tool for both scaling and code

generation. For fixed-point in Simulink environment the user can specify scaling

by choosing the type of the signal, or the parameter, and the maximum and

minimum ranges or by simply choosing the type of the signal/parameter, the

scaling factor and the offset. The maximum and minimum of the block will then

be automatically calculated.

3.1.1 Automatic Scaling

Automatic scaling can be performed on the whole model. This is done by feeding

the model with as much information as possible. The user should enter maximum

and minimum ranges of all known signals and parameters. Since all inputs and

outputs ranges are known, these are propagated to adjacent blocks following the

signal lines forward and backward. The automatic scaling tool, called autoscaling

in TargetLink, can then be chosen and a worst case scaling is determined. A

limitation for TargetLink automatic scaling is that closed loops in the model will

stop the automatic scaling process unless at least one block ranges are specified

by the user.

Simulation based scaling is also supported in TargetLink. This gives the user the

responsibility to enter the worst case simulation inputs to obtain useful results.

3.1.2 Generating Code for One Subsystem

TargetLink makes it possible to generate code for one subsystem by choosing to

generate a separate file for the subsystem during code generation. This is done by

adding a Function block which is a TargetLink block that makes it possible to

generate separate code for the chosen subsystem. Code can also be generated for

the subsystem only, without needing to generate code for the whole model. All of

these are possible via the Function block [2].

3.1.3 Code Interface

The user of TargetLink has the freedom to influence the interface of the generated

code in an easy and practical way. The user can choose the output value for any

subsystem in the model to be a reference variable, a return value, a pointer

parameter or a global variable, see Table 1 [3]. There is also flexibility in

choosing the generated function parameters since every signal and parameter can

be chosen to fulfil certain functionality in the generated code, see Table 1.

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MATLAB REAL-TIME WORKSHOP EMBEDDED CODER - S Manuale Utente Pagina 15