ParamSet
Overview
Sets parameters in other modules
Discussion
The ParamSet module takes a signal from an input wire and writes the value to an instance variable in another module. The module is useful for controlling the behavior of other modules in response to control signals or audio signals.
At instantiation time (or in Module Name and Arguments in Audio Weaver Designer), you specify the data type of the input pin and also the variable which will be written. The variable is specified as
Mod.Var
where Mod is the name of the module (in the same level of the hierarchy as the ParamSet module) and Var is the variable name. You can also specify modules that are within subsystems using
Subsystem.Mod.Var.
You can also go up in hierarchy and control modules that are in an upper system. Use a single backslash character to move up one level in the hierarchy. Use multiple backslash characters to traverse multiple levels of hierarchy. Suppose that the ParamSet module is located in:
SYS.Subsystem.ParamSet
and you want to control the variable
SYS.Scaler1.gain
Then set the Mod.Var field to
\Scaler1.gain
And finally, you can also write to individual values in arrays using the syntax
Mod.Var[index]
where index is the zero-based index of the element in the array Var to set.
The variable .setBehavior determines how often the instance variable is updated and whether the module's set function is called. setBehavior is a bit field. Bit 0 specifies whether the instance variable is always updated (=0) or only if the value on the input wire changes (=1). Bit 1 specifies whether the set function of the module being control is called. (=0 do not call set. =1 call set function). There are 5 possibilities:
0 = Always update. Do not call set function (useful)
1 = Always update. Call set function (not too useful)
2 = Update only when input value changes. Do not call set function (useful)
3 = Update only when input value changes. Call set function (Most useful)
4 = Update only when input value changes. Call set function immediately (not deferred)
Note that in cases 1 and 3 the set function is triggered by setting the deferred bit in the module instance structure which causes the module's set function to be called as a background task. It may take tens of milliseconds before the set function is actually called and the exact timing can depend upon the CPU loading of the system. If the system is lightly loaded then there is more CPU power available for performing the deferred processing tasks. For case 4, the set function is called immediately in the real-time thread. Use with caution since this increases the CPU load.
The input wire can have any number of channels and any block size The module only uses the first value in the wire and ignores all others.
Internally the module uses two pointers. The first points to the base of the module being controlled. The second pointer points at the variable being written.
Please see the ParamSet example for specific use cases.
Type Definition
typedef struct _ModuleParamSet
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
INT32 setBehavior; // Controls the behavior of the module
void * modPtr; // Points to the module to set
void * varPtr; // Points to the variable to set within the module instance structure
} ModuleParamSetClass;
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
setBehavior | int | parameter | 0 | 3 | Unrestricted | |
modPtr | void * | parameter | 1 | Unrestricted | ||
varPtr | void * | parameter | 1 | Unrestricted |
Pins
Input Pins
Name: in
Description: parameter value
Data type: {float, int, fract32}
Channel range: Unrestricted
Block size range: Unrestricted
Sample rate range: Unrestricted
Complex support: Real
MATLAB Usage
File Name: param_set_module.m
M=param_set_module(NAME, DATATYPE, MODVAR)
Parameter set module. This module can reach into the instance structure
of other modules and set parameter values. Arguments:
NAME - name of the module.
DATATYPE - string specifying the data type of the variable and this
is also used for the data type of the input pin. Allowable
values are 'float', 'int', or 'fract32'.
VARNAME - specifies the module and variable name using the form:
'MOD.VAR' where MOD is the module name and VAR is the
variable name. You can also specify internal subsystems using
'SUBSYS.MOD.VAR'.