Target Language Compiler

A Basic Example

This section presents a basic example of creating a target language file that generates specific text from a Real-Time Workshop model. This example shows the sequence of steps that you should follow in creating and using your own target language files.

Process

To begin, create the Simulink model shown below and save it as basic.mdl.

Figure 3-1: Simulink Model

Selecting Simulation Parameters from Simulink's Simulation menu displays the Simulation Parameters dialog box.

Figure 3-2: Simulation Parameters Dialog Box

Select Fixed Step Solver from the Simulation Parameters dialog box and then move to the Real-Time Workshop tab. Then, click the Generate Code only button. Next, move to the Category drop down list and select the TLC Debugging option. The tab changes and you should check the Retain .rtw file option. Next, click the Generate Code button.

The build process then generates the code into the basic_grt_rtw directory and you can see the progress in the MATLAB window.

The output eventually says:

### Successful completion of Real-Time Workshop build procedure for model: basic

Viewing basic.rtw.   

Open the file ./basic_grt_rtw/basic.rtw in a text editor to see what it looks like. The file should look similar to this

CompiledModel {
   Name                   "basic"
   ...
   <General model information such as>
   Solver                 FixedStepDiscrete
   ...
   BlockOutputs {
      -- Information blocks output signals: characteristics and  connectivity
      BlockOutputDefaults {
      TestPoint               no
      ...
      }
      ...
      BlockOutput {
         Identifier           Constant
         SigIdx               [0, 1]
         StorageClass         DefinedInTLC
         SigSrc               [0, 0, 0]
      }
   }
   ...
   System {
      <Subsystem description>
      Type                  root
      Name                  "<Root>"
      ...
      <Blocks in subsystem, listed by block execution order>
      Block {
         Type                 Constant
         Name                 "<Root>/Constant"
         ...
         Parameters           [1, 1]
         Parameter {
           Name                 "Value"
           ...
         }
      }
      ...
   }
  ...
}

Creating the Target File.   Next, create a basic.tlc file to act as a target file for this model. However, instead of generating code, simply print out some information about the model using this file. The concept is the same as used in code generation.

Create a file called basic.tlc in ./ (the directory containing basic.mdl). This file should contain the following lines

%with CompiledModel

My model is called %<Name>.
It was generated on %<GeneratedOn>.

It has %<NumModelOutputs> output(s) and %<NumContStates> continuous states.

%endwith

For the build process, you need to include some further information in the TLC file for the build process to successfully proceed. Instead, in this example, you will generate the .rtw file directly and then run the Target Language Compiler on this file to generate the desired output. To do this, enter at the MATLAB prompt

rtwgen('basic', 'OutputDirectory', 'basic_grt_rtw')
tlc -r basic_grt_rtw/basic.rtw basic.tlc -v

The first line generates the .rtw file in the build directory 'basic_grt_rtw', (this step is actually unnecessary since the file has already been generated in the previous step; however, it will be useful if the model is changed and the operation has to be repeated).

The second line runs the Target Language Compiler on the file basic.tlc. The -r option tells the Target Language Compiler that it should use the file basic.rtw as the .rtw file, and -v tells TLC to be verbose.

The output of this pair of commands is

My model is called basic.
It was generated on Tue May 09 11:41:40 2000.

It has 1 output(s) and 0 continuous states.

You may also try changing the model (such as using rand(2,2) as the value for the constant block) and then repeating the process to see how the output of TLC changes.

As you continue through this chapter, you will learn more about creating target files.

Code Generation Architecture

Invoking TLC to Generate Code