Matrix Multiplication Operation to ANSI/ISO C BLAS Code Replacement

You can develop a code replacement library for floating-point matrix/matrix and matrix/vector multiplication operations with the multiplication functions sgemm defined in the MathWorks C BLAS library. Use a third-party C BLAS library for replacement and change the build requirements in this example to point to your library. To develop a code replacement library use either the interactive or programmatic approach. For more information, see Develop a Code Replacement Library.

Interactively Develop a Code Replacement Library

Open the Code Replacement Tool (crtool), from the MATLAB command line with the following command:
```
>>crtool
```
Create a table.
1. From the crtool context menu, select File > New Table.
2. In the right pane, name the table crl_table_cblas. Click Apply.
Create an entry. From the crtool context menu, select Edit > New entry > CBlas Operation (Atlas).
Create entry parameters. In the Operation drop-down list, select Multiply.
Create the conceptual representation. The conceptual representation describes the signature of the function that you want to replace. In the Conceptual function subsection of the crtool, specify the return argument, y1, and the input argument, u1 and u2 with the Data Type of single and the Argument Type of Matrix.
Create the implementation representation. The implementation representation describes the signature of the optimization function. For this example, to specify that the implementation arguments have the same order and properties as the conceptual arguments, select the Make conceptual and implementation argument types the same check box. Set the BLAS level to 3(Vector).
Specify a Name for the replacement function under Function prototype.
Specify build information. Click the Build Information tab to open the build requirements pane. Specify the files (source, header, object) that the code generator requires for code replacement. For this example, you do not need to specify build information.
Validate and save the table. In the Mapping Information tab, click Validate entry. In the crtool context menu, select File > Save table > Save.
Register a code replacement library. Registration creates a library composed of the tables that you specify. Select File > Generate registration file. In the Generate registration file dialog box, fill out these fields:
To use your code replacement library, refresh your current MATLAB session with the command:
```
>>sl_refresh_customizations
```
Verify the code replacement library. From the MATLAB command line, open the library by using the Code Replacement Viewer and verify that the table and entry are correctly specified. For more information, see Verify Code Replacement Library. Configure your model to use the code replacement library, generate code, and verify that replacement occurs as expected. If unexpected behavior occurs, examine the hit and miss logs to troubleshoot the issues.

Programmatically Develop a Code Replacement Library

Open the programmatic interface from the MATLAB menu by selecting New > Function.
Create a table.
1. Create a function to call your code replacement library table. The function should not have arguments and return a table object.
2. Create a table object by calling RTW.TflTable.
```
function hTable = crl_table_cblas
% Create a function to call the code replacement library table 

%% Create a table object
hTable = RTW.TflTable;
```

Create an entry. Because this example replaces a function, create a code replacement entry in your table by calling the entry function RTW.TflCBlasEntryGenerator.

function hTable = crl_table_cblas
% Create a code replacement library table 

%% Create a table object
hTable = RTW.TflTable;

%% Create an entry
%%%%%%%%%%%% Define library path Cblas library file%%%%%%%%%%%%%%%%%%

LibPath = fullfile('<Specify the path of your cblas library>');

if ispc
    libExt = 'lib';
elseif ismac
    libExt = 'dylib';
else
    libExt = 'so';
end


% Create table entry for dgemm32
hEntry = RTW.TflCBlasEntryGenerator;

Create entry parameters. Because this examples replaces a function, create entry parameters by calling the function setTflCFunctionEntryParameters.

function hTable = crl_table_cblas
% Create a code replacement library table 

%% Create a table object
hTable = RTW.TflTable;

%% Create an entry
%%%%%%%%%%%% Define library path Cblas library file%%%%%%%%%%%%%%%%%%

LibPath = fullfile('<Specify the path of your cblas library>');

if ispc
    libExt = 'lib';
elseif ismac
    libExt = 'dylib';
else
    libExt = 'so';
end


% Create table entry for dgemm32
hEntry = RTW.TflCBlasEntryGenerator;

%% Create entry parameters
hEntry.setTflCOperationEntryParameters( ...
    'Key', 'RTW_OP_MUL', ...
    'Priority', 100, ...
    'ImplementationName', 'cblas_sgemm', ...
    'ImplementationSourceFile', 'ccblas.c', ...
    'ImplementationHeaderFile', 'ccblas.h', ...
    'AdditionalIncludePaths',   {LibPath}, ...
    'AdditionalLinkObjs',       {['libcblas' libExt]}, ...
    'AdditionalLinkFlags',        {'-lgfortran'},...
    'SideEffects', true);

Create the conceptual representation. The conceptual representation describes the signature of the function that you want to replace. To explicitly specify argument properties, call the function createAndAddConceptualArg. To specify a matrix argument in the function call, use the argument class RTW.TflArgMatrix and specify the base type and the dimensions for which the argument is valid. This type of table entry supports a range of dimensions specified in the format[Dim1Min Dim2Min ... DimNMin; Dim1Max Dim2Max ... DimNMax]. For example, [2 2; inf inf] means a two-dimensional matrix of size 2x2 or larger.

function hTable = crl_table_cblas
% Create a code replacement library table 

%% Create a table object
hTable = RTW.TflTable;

%% Create an entry
%%%%%%%%%%%% Define library path Cblas library file%%%%%%%%%%%%%%%%%%

LibPath = fullfile('<Specify the path of your cblas library>');

if ispc
    libExt = 'lib';
elseif ismac
    libExt = 'dylib';
else
    libExt = 'so';
end


% Create table entry for dgemm32
hEntry = RTW.TflCBlasEntryGenerator;

%% Create entry parameters
hEntry.setTflCOperationEntryParameters( ...
    'Key', 'RTW_OP_MUL', ...
    'Priority', 100, ...
    'ImplementationName', 'cblas_sgemm', ...
    'ImplementationSourceFile', 'ccblas.c', ...
    'ImplementationHeaderFile', 'ccblas.h', ...
    'AdditionalIncludePaths',   {LibPath}, ...
    'AdditionalLinkObjs',       {['libcblas' libExt]}, ...
    'AdditionalLinkFlags',      {'-lgfortran'},...
    'SideEffects', true);

%% Create the conceptual representation
arg = RTW.TflArgMatrix('y1', 'RTW_IO_OUTPUT',  'single');
arg.DimRange = [2 2; Inf Inf];
hEnt.addConceptualArg(arg);

arg = RTW.TflArgMatrix('u1', 'RTW_IO_INPUT',  'single');
arg.DimRange = [2 1; Inf Inf];
hEnt.addConceptualArg(arg);

arg = RTW.TflArgMatrix('u2', 'RTW_IO_INPUT',  'single');
arg.DimRange = [1 2; Inf Inf];
hEnt.addConceptualArg(arg);

Create the implementation representation. The implementation representation describes the signature of the optimization function. To specify that the implementation arguments have the same order and properties as the conceptual arguments, call the function getTflArgFromString. The example code configures special implementation arguments that are required for dgemm and dgemv function replacements. The convenience methods setReturn and addArgument specify whether an argument is a return value or argument and adds the argument to the entry’s array of implementation arguments. Add the complete entry to the table by calling the function addEntry.

function hTable = crl_table_cblas
% Create a code replacement library table 

%% Create a table object
hTable = RTW.TflTable;

%% Create an entry
%%%%%%%%%%%% Define library path Cblas library file%%%%%%%%%%%%%%%%%%

LibPath = fullfile('<Specify the path of your cblas library>');

if ispc
    libExt = 'lib';
elseif ismac
    libExt = 'dylib';
else
    libExt = 'so';
end


% Create table entry for dgemm32
hEntry = RTW.TflCBlasEntryGenerator;

%% Create entry parameters
hEntry.setTflCOperationEntryParameters( ...
    'Key', 'RTW_OP_MUL', ...
    'Priority', 100, ...
    'ImplementationName', 'cblas_sgemm', ...
    'ImplementationSourceFile', 'ccblas.c', ...
    'ImplementationHeaderFile', 'ccblas.h', ...
    'AdditionalIncludePaths',   {LibPath}, ...
    'AdditionalLinkObjs',       {['libcblas' libExt]}, ...
    'AdditionalLinkFlags',      {'-lgfortran'},...
    'SideEffects', true);

%% Create the conceptual representation

arg = RTW.TflArgMatrix('y1', 'RTW_IO_OUTPUT',  'single');
arg.DimRange = [2 2; Inf Inf];
hEnt.addConceptualArg(arg);

arg = RTW.TflArgMatrix('u1', 'RTW_IO_INPUT',  'single');
arg.DimRange = [2 1; Inf Inf];
hEnt.addConceptualArg(arg);

arg = RTW.TflArgMatrix('u2', 'RTW_IO_INPUT',  'single');
arg.DimRange = [1 2; Inf Inf];
hEnt.addConceptualArg(arg);

%% Create the Implementation Representation
% Using RTW.TflCBlasEntryGenerator for sgemm requires the following
% implementation signature:
%
% void no_name( const integer ORDER, const integer TRANSA, const integer TRANSB, 
% const integer M, const integer N, const integer K, const double ALPHA, 
% const double* u1, const integer LDA, const double* u2, const integer LDB, 
% const double BETA, double* y1, const integer LDC );
%
% When a match occurs, the code generator computes the
% values for M, N, K, LDA, LDB, and LDC and inserts them into the
% generated code. TRANSA and TRANSB are set to 'N'.

% Specify replacement function signature
arg = hEntry.getTflArgFromString('y2','void');
arg.IOType = 'RTW_IO_OUTPUT';
hEntry.Implementation.setReturn(arg); 

arg = hEntry.getTflArgFromString('ORDER','integer',102.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('TRANSA','integer',111.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('TRANSB','integer',111.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('M','integer',0.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('N','integer',0.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('K','integer',0.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('ALPHA','double',1.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('u1','single*');
arg.Type.BaseType.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('LDA','integer',0.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('u2','single*');
arg.Type.BaseType.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('LDB','integer',0.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('BETA','double',0.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('y1','single*');
arg.IOType = 'RTW_IO_OUTPUT';
hEntry.Implementation.addArgument(arg);

arg = hEntry.getTflArgFromString('LDC','integer',0.000000000000000);
arg.Type.ReadOnly = true;
hEntry.Implementation.addArgument(arg);


%% Add the entry to the table
addEntry(hTable, hEntry);

Specify build information. In the entry parameters, specify files (header, source, object) that the code generator needs for code replacement. For this example, build information is not required.
Validate and save the customization file. From the MATLAB menu, save this customization file by selecting File > Save. From the command line, validate the code replacement library table by calling it:
```
>> hTable = crl_table_cblas
```

Register the code replacement library. Registration creates a code replacement library by defining the library name, code replacement tables, and other information. Create a registration file with these specifications:

function rtwTargetInfo(cm)
 
cm.registerTargetInfo(@loc_register_crl);
end
 
function this = loc_register_crl 
 
this(1) = RTW.TflRegistry; 
this(1).Name = 'CRL for matrix multiplication for Mathworks CBlas code’;
this(1).TableList = {'crl_table_cblas.m'}; % table created in this example
this(1).TargetHWDeviceType = {'*'};
this(1).Description = 'Example code replacement library';

end

To use your code replacement library, refresh your current MATLAB session with the command:

>>sl_refresh_customizations

Verify the code replacement library. From the MATLAB command line, open the library by using the Code Replacement Viewer and verify that the table and entry are correctly specified. For more information, see Verify Code Replacement Library. Configure your model to use the code replacement library, generate code, and verify that replacement occurs as expected. If unexpected behavior occurs, examine the hit and miss logs to troubleshoot the issues.