...
The header file also contains a few other items. First, there is a bit mask for each variable in the data structure. The mask corresponds to the position of the variable within the instance structure. Note that the module header is 8 words long and thus the first bit starts in the 9th bit position. These bit masks can be used by the _Set() and _Get() functions to determine which variable within the instance structure has been modified.
| Code Block |
|---|
#define MASK_ScalerSmoothedExample_gain 0x00000100 |
...
#define MASK_ScalerSmoothedExample_smoothingTime 0x00000400 |
...
#define MASK_ScalerSmoothedExample_currentGain 0x00000200 |
...
#define MASK_ScalerSmoothedExample_smoothingCoeff 0x00000800 |
The header file also defines an offset for each instance variable. Again, this is the offset from the start of the data structure, in 32-bit words. These offsets are provided to help implement system control using a host interface.
| Code Block |
|---|
#define OFFSET_ScalerSmoothedExample_gain 0x00000008 |
...
#define OFFSET_ScalerSmoothedExample_smoothingTime 0x0000000A |
...
#define OFFSET_ScalerSmoothedExample_currentGain 0x00000009 |
...
#define OFFSET_ScalerSmoothedExample_smoothingCoeff 0x0000000B |
There is a unique class ID.
...
Each audio module has a set of associated functions. These functions, and their definitions, are placed in .c and .h files, respectively. At a minimum, every audio module requires a processing function. In addition, a module may specify several optional functions:
Constructor() – Performs additional memory allocation or initialization when a module is instantiated. If a module has an indirect array, such as an FIR filter, then a constructor function is required. In many cases, MATLAB can generate the constructor function automatically.
Set() – Implements a module's control functions which translate high-level interface variables to low-level variables. The Set() function is automatically called whenever an internal variable of a module is written by the Server during tuning.
Get() – Implements a module's control functions which translate low-level variables to high-level interface variables. The Get() function is automatically called by the Server whenever an internal variable of a module is read during tuning. Very few modules actually implement this function.
Bypass() – Implements custom bypass functionality. Required when one of the standard bypass functions is not suitable.
The module .c source file also contains a single class structure that describes the module to the Audio Weaver run-time and dynamic memory allocation functions. For example, this module contains the class structure:
| Code Block |
|---|
AWE_MOD_SLOW_ANY_CONST |
...
const Class_awe_modScalerSmoothedExample awe_modScalerSmoothedExampleClass = |
...
{
{
...
{
{
{ NULL, CLASSID_SCALERSMOOTHEDEXAMPLE, }, // |
...
Constructor
awe_modScalerSmoothedExampleProcess, // Processing |
...
function
IOMatchUpModule_Bypass, |
...
// Bypass function
awe_modScalerSmoothedExampleSet, // Set |
...
0, // Get function
0x00000007, // Module version info
function
0, // Get function
0x00000007, // Module version info
ClassModule_PackArgCounts(4, 0), // (Public words, private words) |
...
{0x0000000F, 0x00000000}, // Specifies which variables are floating-point |
...
...
...
{
{
offsetof(awe_modScalerSmoothedExampleInstance, gain), |
...
offsetof(awe_modScalerSmoothedExampleInstance, smoothingTime), |
...
offsetof(awe_modScalerSmoothedExampleInstance, currentGain), |
...
offsetof(awe_modScalerSmoothedExampleInstance, smoothingCoeff), |
...
}
#endif
The class structure contains pointers to the 5 functions listed above. The constructor function is NULL indicating that the module requires no memory outside of its instance structure and that the generic constructor should be used instead.
The #ifdef BUILD64 section is required internally by Designer to correctly access the module’s variables in 64-bit architectures.
| Note |
|---|
Make sure that BUILD64 is defined in the VisualStudio and embedded projects if a 64-bit architecture is being targeted. Failure to add the BUILD64 macro to 64-bit architectures can cause the application to crash while accessing module variables using the control interface. |
The class ID, CLASSID_SCALERSMOOTHEDEXAMPLE which is defined above, is a unique integer identifying the module to the Server. When instantiating a module of this class, the Server is told to instantiate a module of class "ModuleScalerSmoothedExample". This string identifier is then translated to the underlying class ID through the module DLL shown as item 9 in Figure 1. Ensuring that each audio module has a unique classID can be tedious. To facilitate this process, each module library has a text file named classids.csv, shown as item 3 in Figure 1, containing a comma separated list of audio modules and their class IDs. A portion of the file is shown below:
...
...
...
...
...
...
The classID for the ScalerSmoothedExample module equals the IDOFFSET (32768) plus the value listed next to its class name below (0). Class IDs starting with 32768 are reserved for custom audio modules.
...
To create an instance of a smoothly varying scaler on the target, the Server is told "create an instance of class ModuleScalerSmoothedExample and call it Scale1". The Server converts this to the command "create an instance of object 0xBEEF8800" via the schema file. The hexadecimal value 0xBEEF0C16 corresponds to the unique class ID CLASS_ID_MODBASE + 32768
...
contained in the class structure.
...
Note: CLASS_ID_MODBASE = 0x BEEF0800, which is defined in Framework.h.
On the target, the array of module class objects is traversed looking for class ID 0xBEEF8800. Once the class object is found, the corresponding constructor function, stored as a pointer in the class structure, is used to allocate one instance of the object. The address of the newly instantiated object is returned to the Server, and the Server associates the object's address with the name "Scale1". The Server maintains this mapping between symbol names and actual memory addresses.
...
will be created in MATLAB's current working directory. Specify the directories for code generation with the second argument:
| Code Block |
|---|
homeDir = awe_home('awecore'); |
...
SRC_DIR = [homeDir '\Source\Examples\Source']; |
...
INC_DIR = [homeDir '\Source\Examples\Include']; |
...
DOC_DIR = [homeDir '\Source\Examples\Doc']; |
...
INNER_DIR = [homeDir '\Source\Examples\Inner']; |
...
DIR = {SRC_DIR; INC_DIR; DOC_DIR; INNER_DIR}; |
...
M = scaler_smoothed_example_module('temp'); |
...
awe_generate_module(M, DIR); |
The following files will be created in the directories specified by DIR:
...
Modules are usually not created in isolation, but are part of a particular module pack library. Modules need to be created as a unified library so that the combined schema file ExamplesSchema.sch can be written. The MATLAB script make_examples.m generates code for the entire Examples module library. The script first creates a cell array of audio modules:
...
MM{end+1}=downsampler_example_module('temp', 2); % 100% instantiation |
...
MM{end+1}=fader_example_fract32_module('temp'); |
...
MM{end+1}=fader_example_module('temp'); |
...
MM{end+1}=lah_limiter_example_module('temp', 5); % 100% instantiation |
...
MM{end+1}=peak_hold_example_fract32_module('temp'); |
...
MM{end+1}=peak_hold_example_module('temp'); |
...
MM{end+1}=scaler_example_module('temp'); |
...
MM{end+1}=scaler_smoothed_example_module('temp'); |
Important point to be noted here is that the module must be added to cell array with all the arguments required. This is mandatory for new AWE Designer.
Some other example audio modules are subsystems that utilize modules found in other libraries. We indicate this dependency relationship using the lines
| Code Block |
|---|
[DependMM, DependName]=make_standardmodulepack(0); |
...
...
USESLIB{1}.str=DependName; |
...
[DependMM, DependName]=make_deprecatedmodulepack(0); |
...
...
USESLIB{2}.str=DependName; |
...
[DependMM, DependName]=make_advancedmodulepack(0); |
...
...
USESLIB{3}.str=DependName; |
Then call a function to generate the source code for the overall library:
...
Audio Weaver uses template substitution to generate audio module source and header files. The template files are shown as item 2 in the Audio Weaver module design environment image, https://dspconcepts.atlassian.net/wiki/spaces/DOCTEST/pages/2690711610/Module+Development+Overview#OverallEnvironment and two files are used:
<AWE>\matlab\module_generation\templates\awe_module_template.c
<AWE>\matlab\module_generation\templates\awe_module_template.h
The template files contain boiler plate text together with string substitution variables and special preprocessor directives. Consider a portion of the file awe_module_template.h:
...
...
...
...
#ifndef _MOD_$classNameUpperCase$_H |
...
#define _MOD_$classNameUpperCase$_H |
...
...
Each substitution point is shown as $NAME$ in the template file. These substitution points are replaced with the code markers added via awe_addcodemarker.m commands in the module file. For example, when generating the scaler_smoothed_example_module, the string variable $description$ is replaced by "Linear multichannel smoothly varying scaler" and $classNameUpperCase$ is replaced by "ScalerSmoothedExample" to yield:
...
@brief Linear multichannel smoothly varying scaler
*/
...
* @file
* @brief Linear multichannel smoothly varying scaler
*/
#ifndef _MOD_SCALERSMOOTHEDEXAMPLE_H |
...
#define _MOD_SCALERSMOOTHEDEXAMPLE_H |
...
...
| Info |
|---|
By making changes to the template files, you can make wholesale changes to the entire module library |
...
The template files also contain special forms of preprocessor directives – independent of the standard C preprocessor directives. Further down in awe_module_template.h, you'll find the function declarations:
| Code Block |
|---|
void $processFunctionName$(void *pInstance); |
...
##if $useCustomSetFunction$ |
...
UINT $setFunctionName$(void *pInstance, UINT mask); |
...
...
##if $useCustomGetFunction$ |
...
UINT $getFunctionName$(void *pInstance); |
...
...
##if $useCustomBypassFunction$ |
...
void $bypassFunctionName$(void *pInstance); |
...
The symbol symbols ## identifies identify a preprocessor directive reserved for the code generator. The directives are evaluated during code generation based on the values of the variables, for example the value of $useCustomSetFunction$ determines if code will be eliminated or exist in the generated file. The scaler smoothed example module has:
$useCustomSetFunction$ defined as 1
$useCustomGetFunction$ defined as 0
$useCustomBypassFunction$ defined as 0.
This yields the generated header code:
| Code Block |
|---|
void awe_modScalerSmoothedExampleProcess(void *pInstance); |
...
UINT32 awe_modScalerSmoothedExampleSet(void *pInstance, UINT32 mask); |
The variables used during template substitution are referred to as "code markers". Many code markers are generated automatically by the awe_generate_module.m function. Some code markers are explicitly defined in scaler_smoothed_example_module.m.
| Code Block |
|---|
awe_addcodemarker(M, 'processFunction', 'Insert:InnerScalerSmoothed_Process.c'); |
...
awe_addcodemarker(M, 'setFunction', 'Insert:InnerScalerSmoothed_Set.c'); |
...
awe_addcodemarker(M, 'srcFileInclude', '#include "FilterDesign.h"'); |
Code markers beginning with the string "Insert:" cause input to be read from a specified file. For example, the processing function template in awe_module_template.c is:
...
void $processFunctionName$(void *pInstance) |
...
...
##if $usePreProcessFunction$ |
...
{
$preProcessFunction$
}
##endif
$processFunction$
##if $usePostProcessFunction$
{
$postProcessFunction$
}
##endif
{
$preProcessFunction$
}
##endif
$processFunction$
##if $usePostProcessFunction$
{
$postProcessFunction$
}
##endif
} |
The string $processFunction$ is taken from the file Inner\InnerScalerSmoothedExample_Process.c
shown in Section 2.9.2. the section InnerScalerSmoothedExample_Process.c. You'll note that this is bare code missing even the function definition (which is in the template file). The other code markers – "preProcessFunction" and "postProcessFunction" are not defined. After template substitution, we end up with the final processing function ModScalerSmoothedExample.c shown in Section 2.9.5.2.7. the section ModScalerSmoothedExample.c.
Building the Audio Module DLL
At this point, the source code for all of the modules in the Examples library has been generated. Open up and rebuild the VisualStudio solution file <AWE>\AWEModules\Source\Examples\Examples.sln.
with the build configuration set to x86 Release. The solution builds the DLL and then copies it into the directory <AWE>\Bin\win32-vc100-reldirectory so that it can be referenced by the Server. Further details on this step can be found in Section 8.1.2.8. https://dspconcepts.atlassian.net/wiki/spaces/DOCTEST/pages/2690908220/Building+Audio+Module+DLLs#BuildingExamplesDLL.dll.
Summary of Steps Involved in Writing an Audio Module
To summarize, the steps required in writing a new audio module are:
Create the MATLAB module m-file described in Section 2.1. It defines:
...
Input and output pins
...
Instance structure variables
...
Links to inner C code.
...
Documentation
...
User interface
...
Module browser for AWE Designer
Write the inner C code for the processing function.
Write the inner C code for the other module functions, Constructor(), Set(), Get(), and Bypass(), if needed.
Pick a unique integer ID (any number in the range 32768 to 63487) for the new module class ID. Add this information to the file classids.csv associated with the module library.
Add the module function to the specific module pack library generation script, for example make_examples.m. Run the script file to generate the source code and create the schema file.
Add the generated .c and .h files to the project for building the audio module pack library (e.g., ExamplesLib.vcproj) . And and build the library.
Build the audio module DLL so that the new modules are visible by the Server.
Scaler Smoothed Example Source Files
| Anchor |
|---|
| ScalerSmoothedExampleSourceFiles |
|---|
| ScalerSmoothedExampleSourceFiles |
|---|
|
2.9.1. The following sections feature expandable
scaler_smoothed_example_module.m
| Expand |
|---|
| Code Block |
|---|
function M=scaler_smoothed_example_module(NAME) |
|
...
% M=scaler_smoothed_example_module(NAME) |
|
...
% Creates a smoothly varying scaler module with a single input |
|
...
% and single output pin. This module operates on floating-point |
|
...
...
% NAME - name of the module. |
|
...
% Copyright 2007-2016. DSP Concepts, Inc. All Rights Reserved. |
|
...
% ---------------------------------------------------------------------- |
|
...
% Create the high-level object with interface variables only. |
|
...
% ---------------------------------------------------------------------- |
|
...
M=awe_module('ScalerSmoothedExample', 'Linear multichannel smoothly varying scaler'); |
|
...
% Version is auto-updated by SVN: |
|
...
M.moduleVersion = generate_version('$Revision: 30333 $'); |
|
...
...
...
...
...
M.preBuildFunc=@scaler_smoothed_example_prebuild; |
|
...
M.processFunc=@scaler_smoothed_example_process; |
|
...
M.setFunc=@scaler_smoothed_example_set; |
|
...
...
add_pin(M, 'input', 'in', 'audio input', PT); |
|
...
add_pin(M, 'output', 'out', 'audio output', PT); |
|
...
add_variable(M, 'gain', 'float', 0, 'parameter', 'Target gain'); |
|
...
...
...
add_variable(M, 'smoothingTime', 'float', 10, 'parameter', 'Time constant of the smoothing process'); |
|
...
M.smoothingTime.range=[0 1000]; |
|
...
M.smoothingTime.units='msec'; |
|
...
add_variable(M, 'currentGain', 'float', M.gain, 'state', 'Instantaneous gain applied by the module. This is also the starting gain of the module.', 1); |
|
...
M.currentGain.range=M.gain.range; |
|
...
M.currentGain.units='linear'; |
|
...
add_variable(M, 'smoothingCoeff', 'float', NaN, 'derived', 'Smoothing coefficient', 1); |
|
...
awe_addcodemarker(M, 'processFunction', 'Insert:InnerScalerSmoothedExample_Process.c'); |
|
...
awe_addcodemarker(M, 'setFunction', 'Insert:InnerScalerSmoothedExample_Set.c'); |
|
...
awe_addcodemarker(M, 'srcFileInclude', '#include "FilterDesign.h"'); |
|
...
M.wireAllocation='across'; |
|
...
% ---------------------------------------------------------------------- |
|
...
...
% ---------------------------------------------------------------------- |
|
...
M.docInfo.discussion={'Scales all input channels by a single gain value. ', ... |
|
...
'Changes to the gain parameter are exponentially smoothed (first order IIR) at the sample rate, with the time constant determined by the smoothingTime parameter. ', ... |
|
...
'This module is controlled by varying the gain variable. Internally, currentGain represents the instantaneous smoothed gain that is applied. ', ... |
|
...
'currentGain exponentially approaches gain with a time constant equal to smoothingTime. ', ... |
|
...
...
'The module''s prebuild function initializes the currentGain equal to the gain. Thus, the module begins in a converged state.'}; |
|
...
% ---------------------------------------------------------------------- |
|
...
% Add the inspector information |
|
...
% ---------------------------------------------------------------------- |
|
...
...
M.gain.guiInfo.controlType='slider'; |
|
...
...
add_control(M, '.moduleStatus', 'right', 1); |
|
...
add_control(M, '.smoothingTime', 'below', 1); |
|
...
% ---------------------------------------------------------------------- |
|
...
% Module browser information |
|
...
% ---------------------------------------------------------------------- |
|
...
M.moduleBrowser.path = 'Examples'; |
|
...
M.moduleBrowser.image = '../images/ExamplesIcon.bmp'; |
|
...
M.moduleBrowser.searchTags = 'scaler volume'; |
|
...
M.shapeInfo.basicShape = 'triangle'; |
|
...
M.shapeInfo.legend = ' '; |
|
...
...
% ---------------------------------------------------------------------- |
|
...
% Prebuild function. Behavior is based on the data type of the |
|
...
...
% ---------------------------------------------------------------------- |
|
...
function M=scaler_smoothed_example_prebuild(M) |
|
...
...
M.currentGain.range=M.gain.range; |
|
...
% Propagate the type of the input pin to the output |
|
...
M.outputPin{1}.type=M.inputPin{1}.type; |
|
...
...
% ---------------------------------------------------------------------- |
|
...
% Set function. Computes the smoothing coefficient |
|
...
% ---------------------------------------------------------------------- |
|
...
function M=scaler_smoothed_example_set(M) |
|
...
% Compute the smoothing coefficient based on the smoothing time |
|
...
SR=M.inputPin{1}.type.sampleRate; |
|
...
M.smoothingCoeff = design_smoother(M.smoothingTime, SR, 1); |
|
...
...
InnerScalerSmoothedExample_Process.c
| Anchor |
|---|
| InnerScalerSmoothedExample_Process.c |
|---|
| InnerScalerSmoothedExample_Process.c |
|---|
|
awe_modScalerSmoothedExampleInstance *S = (awe_modScalerSmoothedExampleInstance *)pInstance;
...
#endif // _MOD_SCALERSMOOTHEDEXAMPLE_H
/**
*
*/2.9.5.
ModScalerSmoothedExample.c
| Anchor |
|---|
| ModScalerSmoothedExample.c |
|---|
| ModScalerSmoothedExample.c |
|---|
|
/****************************************************************************
...
