A TLC Tutorial (Target Language Compiler)

Target Language Compiler

Passing and Using a Parameter

As we described above, and as you demonstrated by using the built-in function GET_COMMAND_SWITCH(), you can use the MATLAB tlc command to pass parameters from the command line to the TLC file being executed. The most general command switch is -a, which assigns arbitrary variables. For example:

tlc -r input.rtw -avar=1 -afoo="abc" any.tlc

The result of passing this pair of strings via -a is the same as declaring and initializing local variables in the file being executed (here, any.tlc), i.e.,

```
%assign var = 1
%assign foo = "abc"
```

Note that such variables need not be declared in the TLC file, and are available for use when set with -a. However, errors result if the code assigns undeclared variables that are not specified by an -a switch when invoking the file. Also note that (in contrast to the -r switch) no space should separate -a from the parameter being declared.

In the final section of this exercise, we provide a parameter to control whether or not the names of blocks are printed out. By default block names are listed, but are suppressed if the command line contains -alist=0.

Open listrtw2.tlc in your editor and save it as listrtw3.tlc

Below the line %include "utillib.tlc" you need to check whether a list parameter has been declared, via the intrinsic (built-in) function EXISTS(). Should no list variable exist, your program assigns one:
- ```
%include "utillib.tlc"
%if (!EXISTS(list))
    %assign list = 1
%endif
```
This code ensures that list is defined and by default its value is TRUE.

Next, enclose the line that prints block names within an %if block:

%if (list)
    %<LibGetFormattedBlockPath(Block[blkIdx])>
%endif

Now LibGetFormattedBlockPath is called and expanded into text only when list is TRUE.

Save listrtw3.tlc and cverify that your changes work as expected, using the command

```
tlc -r f14a.rtw -alist=0 listrtw3.tlc
```

With the -alist=0 switch, the output resembles that from listrtw1.tlc, except that the input filename is reported as well as the block and subsystem counts.

Finally, execute listrtw3.tlc with the command:

tlc -r f14a.rtw listrtw3.tlc

This yields the same results as you obtained with listrtw2.tlc. Here is the output printed to the MATLAB command window:

*** SYSTEMS AND BLOCKS IN RECORDFILE [f14a.rtw]
    f14a/Aircraft Dynamics Model/Transfer Fcn.1
    f14a/Aircraft Dynamics Model/Gain3
    f14a/Aircraft Dynamics Model/Transfer Fcn.2
    f14a/Aircraft Dynamics Model/Gain4
    f14a/Aircraft Dynamics Model/Gain5
    f14a/Aircraft Dynamics Model/Gain6
    f14a/Aircraft Dynamics Model/Sum1
    f14a/Aircraft Dynamics Model/Sum2
*** 8 blocks in system 1        
    f14a/Controller/Alpha-sensor Low-pass Filter
    f14a/Controller/Stick Prefilter
    f14a/Controller/Pitch Rate Lead Filter
    f14a/Controller/Gain2
    f14a/Controller/Gain3
    f14a/Controller/Sum1
    f14a/Controller/Sum2
    f14a/Controller/Gain
    f14a/Controller/Proportional plus integral compensator
    f14a/Controller/Sum
*** 10 blocks in system 2        
    f14a/Dryden Wind Gust Models/Band-Limited White Noise/White Noise
    f14a/Dryden Wind Gust Models/Band-Limited White Noise/Gain
    f14a/Dryden Wind Gust Models/W-gust model
    f14a/Dryden Wind Gust Models/Q-gust model
*** 4 blocks in system 3        
    f14a/Nz pilot calculation/Constant
    f14a/Nz pilot calculation/Derivative
    f14a/Nz pilot calculation/Derivative1
    f14a/Nz pilot calculation/Gain1
    f14a/Nz pilot calculation/Product
    f14a/Nz pilot calculation/Sum1
    f14a/Nz pilot calculation/Gain2
*** 7 blocks in system 4        
    f14a/Actuator Model
    f14a/Dryden Wind Gust Models
    f14a/Gain
    f14a/Gain2
    f14a/Gain1
    f14a/Sum
    f14a/Aircraft Dynamics Model
    f14a/Gain5
    f14a/alpha (rad)
    f14a/Nz pilot calculation
    f14a/Nz Pilot (g)
    f14a/Angle of  Attack
    f14a/Pilot G force Scope
    f14a/Pilot
    f14a/Sum1
    f14a/Stick Input
    f14a/Controller
*** 17 blocks in system 5        
*** recordfile [f14a.rtw] contains 46 blocks in 5 systems 
*** END LISTING

Congratulations! You have crafted several Target Language Compiler programs that access model.rtw files, and run them from the command line.

Listing Block Names Inlining S-Functions with TLC