%% Inputs Passed by Value or Address to Legacy Functions
% This example shows you how to use the Legacy Code Tool to integrate legacy C 
% functions that pass their input arguments by value versus address. 
%
% The Legacy Code Tool allows you to:
%
% * Provide the legacy function specification,
% * Generate a C-MEX S-function that is used during simulation to call the legacy code, and
% * Compile and build the generated S-function for simulation.
%

%   Copyright 1990-2020 The MathWorks, Inc.

%% 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.
% The prototypes of the legacy functions being called in this example are:
%
% * FLT filterV1(const FLT signal, const FLT prevSignal, const FLT gain)
% * FLT filterV2(const FLT* signal, const FLT prevSignal, const FLT gain)
%
% where FLT is a typedef to float.  The legacy source code is found in the
% files |your_types.h|, |myfilter.h|, |filterV1.c|, and |filterV2.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_filterV1
def = 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_filterV2
def = 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 files
% |sldemo_sfun_filterV1.c| and |sldemo_sfun_filterV2.c|.

legacy_code('generate_for_sim', defs);

%% 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(R) Coder(TM). 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);

%% Integrate the Legacy Code
% The model |sldemo_lct_filter| shows 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');
