MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Guide de l'utilisateur télécharger pdf (Page 170)

4 Guidelines for Writing C MEX S-Functions

4-4

The MathWorks has a dopted terminology for these different requirements.

Respectively, the situations described above map to this terminology:

1 Noninlined S-function

2 Wrapper S-function

3 Fully inlined S-function

Noninlined S-Functions

A noninlined S-function is a C-MEX S-function that is treated identically by

Simulink and the Real-Time Workshop. In general, you implement your

algorithm once according to the S-function API. Simulink and the Real-Time

Workshop call the S-function routines (e.g.,

mdlOutputs) at the appropriate

points during model execution.

Significant memory and computation resources are required for each instance

of a noninlined S-function block. However, this routine of incorporating

algorithms into Simulink and the Real-Time Workshop is typical during the

prototyping phase of aprojectwhere efficiencyis notimportant.The advantage

gained by foregoing efficiency is the ability to change model parameters and/or

structures rapidly.

Note that writing a noninlined S-function does not involve any TLC coding.

Noninlined S-functionsare the default case for the Real-Time Workshop in the

sense that once you’ve built a C-MEX S-function in your model, there is no

additional preparation prior to clicking

Build in the RTW Page of the

Simulation Parameters dialog box for your model.

Wrapper S-Functions

A wrapper S-function is ideal for interfacing hand-written code or a large

algorithm t hat is encapsulated within a few procedures. In this situation,

usually the procedures reside in modules that are separate from the C-MEX

S-function. The S-f unction module typically contains a few calls to your

procedures. Since t he S-functi on module does not contain any parts of y our

algorithm, b ut o nly calls yo ur code, it is referred to as a wrapper S-function.

In addition to the C-MEX S-func tion wra p per, you n eed to create a TL C

wrapper that complements your S -function. The TLC wrapper is similar to the

S-function wrapper in that it contains calls to your algorithm.

1 2 ... 165 166 167 168 169 170 171 172 173 174 175 ... 209 210

Pas de commentaire

MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Guide de l'utilisateur Page 170