Providing the Legacy Function Specification

Functions provided with the Legacy Code Tool take a specific data structure or array of structures as the argument. The data structure is initialized by calling the function legacy_code() using 'initialize' as the first input. After initializing the structure, you have to assign its properties to values corresponding to the legacy code being integrated. For detailed help on the properties, calllegacy_code('help'). The prototypes of the legacy functions being called in this example are:

where FLT is a typedef to float. The legacy source code is found in the filesyour_types.h,myfilter.h,filterV1.c, andfilterV2.c.

Note the difference in the OutputFcnSpec defined in the two structures; the first case specifies that the first input argument is passed by value, while the second case specifies pass by pointer.

defs = [];% sldemo_sfun_filterV1def = legacy_code('initialize'); def.SFunctionName ='sldemo_sfun_filterV1'；def.OutputFcnSpec ='single y1 = filterV1(single u1, single u2, single p1)'；def.HeaderFiles = {'myfilter.h'}; def.SourceFiles = {'filterV1.c'}; def.IncPaths = {'sldemo_lct_src'}; def.SrcPaths = {'sldemo_lct_src'}; defs = [defs; def];% sldemo_sfun_filterV2def = legacy_code('initialize'); def.SFunctionName ='sldemo_sfun_filterV2'；def.OutputFcnSpec ='single y1 = filterV2(single u1[1], single u2, single p1)'；def.HeaderFiles = {'myfilter.h'}; def.SourceFiles = {'filterV2.c'}; def.IncPaths = {'sldemo_lct_src'}; def.SrcPaths = {'sldemo_lct_src'}; defs = [defs; def];

Generating and Compiling an S-Function for Use During Simulation

The function legacy_code() is called again with the first input set to 'generate_for_sim' in order to automatically generate and compile the C-MEX S-function according to the description provided by the input argument 'defs'. This S-function is used to call the legacy functions in simulation. The source code for the S-function is found in the filesldemo_sfun_filterV1.candsldemo_sfun_filterV2.c.

legacy_code('generate_for_sim', defs);

### Start Compiling sldemo_sfun_filterV1 mex('-I/mathworks/devel/bat/BR2018ad/build/matlab/toolbox/simulink/simdemos/simfeatures/sldemo_lct_src', '-I/tmp/BR2018ad_802882_51908/publish_examples4/tpde3771ae', '-c', '-outdir', '/tmp/BR2018ad_802882_51908/publish_examples4/tpf7e7a4f5_9dad_4547_aec3_78d71c6ed951', '/mathworks/devel/bat/BR2018ad/build/matlab/toolbox/simulink/simdemos/simfeatures/sldemo_lct_src/filterV1.c') Building with 'gcc'. MEX completed successfully. mex('sldemo_sfun_filterV1.c', '-I/mathworks/devel/bat/BR2018ad/build/matlab/toolbox/simulink/simdemos/simfeatures/sldemo_lct_src', '-I/tmp/BR2018ad_802882_51908/publish_examples4/tpde3771ae', '/tmp/BR2018ad_802882_51908/publish_examples4/tpf7e7a4f5_9dad_4547_aec3_78d71c6ed951/filterV1.o') Building with 'gcc'. MEX completed successfully. ### Finish Compiling sldemo_sfun_filterV1 ### Exit ### Start Compiling sldemo_sfun_filterV2 mex('-I/mathworks/devel/bat/BR2018ad/build/matlab/toolbox/simulink/simdemos/simfeatures/sldemo_lct_src', '-I/tmp/BR2018ad_802882_51908/publish_examples4/tpde3771ae', '-c', '-outdir', '/tmp/BR2018ad_802882_51908/publish_examples4/tpf0647b35_1ff7_40ce_99af_671455d596e3', '/mathworks/devel/bat/BR2018ad/build/matlab/toolbox/simulink/simdemos/simfeatures/sldemo_lct_src/filterV2.c') Building with 'gcc'. MEX completed successfully. mex('sldemo_sfun_filterV2.c', '-I/mathworks/devel/bat/BR2018ad/build/matlab/toolbox/simulink/simdemos/simfeatures/sldemo_lct_src', '-I/tmp/BR2018ad_802882_51908/publish_examples4/tpde3771ae', '/tmp/BR2018ad_802882_51908/publish_examples4/tpf0647b35_1ff7_40ce_99af_671455d596e3/filterV2.o') Building with 'gcc'. MEX completed successfully. ### Finish Compiling sldemo_sfun_filterV2 ### Exit

Generating an rtwmakecfg.m File for Code Generation

After the TLC block file is created, the function legacy_code() can be called again with the first input set to 'rtwmakecfg_generate' in order to generate an rtwmakecfg.m file to support code generation through Simulink® Coder™. Generate the rtwmakecfg.m file if the required source and header files for the S-functions are not in the same directory as the S-functions, and you want to add these dependencies in the makefile produced during code generation.

Note: Complete this step only if you are going to simulate the model in accelerated mode.

legacy_code('rtwmakecfg_generate', def);

Generating Masked S-Function Blocks for Calling the Generated S-Functions

After the C-MEX S-function source is compiled, the function legacy_code() can be called again with the first input set to 'slblock_generate' in order to generate masked S-function blocks which are configured to call those S-functions. The blocks are placed in a new model and can be copied to an existing model.

% legacy_code('slblock_generate', defs);

Demoing the Generated Integration with Legacy Code

The modelsldemo_lct_filtershows integration with the legacy code. The subsystem TestFilter serves as a harness for the calls to the legacy C functions via the generate S-functions, with unit delays serving to store the previous output values.

open_system('sldemo_lct_filter') open_system('sldemo_lct_filter/TestFilter') sim('sldemo_lct_filter')