MATLAB REAL-TIME WORKSHOP 7 - TARGET LANGUAGE COMPILER Betriebsanweisung PDF herunterladen (Seite 265)

Implementing Device Drivers

10-7

Implementing Device Drivers

S-functions can be built into MEX-files or compiled and linked with other code

to become part of a stand-alone program. This dual nature is exploited by the

device driver blocks. These blocks are implemented as C code S-functions. They

are compiled as MEX-files so you can place them in your Simulink block

diagram. When you use the same model to build a real-time program, the

source code for the device driver blocks is automatically compiled and linked

with your program.

Additionally, the Real-Time Workshop uses Target Language Compiler

technology that allows you to inline your S-function. By providing a customized

TLC file containing the definition of your block, you can directly generate the

code for your device driver. The advantage of inlining your S-function in this

fashion is the elimination of function call overhead associated with the

S-function interface.

It is helpful to examine existing device driver code in conjunction with this

chapter. The source code for the blocks resides in the following directories:

•

matlabroot/rtw/c/dos/devices directory for the source code to blocks in

doslib.

•

matlabroot/rtw/c/tornado/devices directory for the source code to blocks

vxlib.

There is also an S-function template that provides a useful starting point for

the creation of any S-function. The file is

matlabroot/simulink/src/sfuntmpl.c

matlabroot/simulink/src/sfuntmpl.doc

Note This chapter does not discuss inlining of S-functions. Refer to “Inlining

an S-function” in the Target Language Compiler Reference Guide.

Device drivers are implemented as C MEX S-functions. When you insert these

blocks into your Simulink model, the code generator compiles and links the

block’s source along with the source files used to build your program.

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MATLAB REAL-TIME WORKSHOP 7 - TARGET LANGUAGE COMPILER Betriebsanweisung Seite 265