Overview
FIR filter
Discussion
The FIRSmoothed module implements a direct convolution N-order Finite Impulse Response filter. The module operates on multiple channels with all channels sharing the same set of filter coefficients. The filter coefficients are stored in the array, coeffs, in normal order. The size of the array is numTaps x 1. The state variable array is of size numTaps*numChannels.
...
This modules suports special FIR HW accelerator on ADI SHARC+ processors, in legacy mode. All the channels are processed in FIR accelerator. On SHARC+ processor, additional memory is allocated for accelerator TCB with size of numAcceleratorChannels*13.
Type Definition
| Code Block |
|---|
typedef struct _ModuleFIRSmoothed
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
INT32 numTaps; // Length of the filter.
FLOAT32 smoothingTime; // Time constant of the smoothing process.
FLOAT32 smoothingCoeff; // Smoothing coefficient. This is computed based on the smoothingTime, sample rate, and block size of the module.
INT32 stateIndex; // Index of the oldest state variable in the array of state variables.
FLOAT32* coeffs; // Filter coefficient array in normal order.
FLOAT32* currentCoeffs; // Smoothly updating filter coefficient array in normal order.
FLOAT32* state; // State variable array. The size of the array equals stateLen * numChannels.
void * hardware_specific_struct_pointer; // This is the internal TCB array used for ADI FIR accelerator
} ModuleFIRSmoothedClass; |
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
numTaps | int | const | 0 | 31 | 1:1:5000 | samples |
smoothingTime | float | parameter | 0 | 10 | 0:1000 | msec |
smoothingCoeff | float | derived | 1 | 0.06449 | Unrestricted | |
stateIndex | int | state | 1 | 0 | Unrestricted | |
coeffs | float* | parameter | 0 | [31 x 1] | Unrestricted | |
currentCoeffs | float* | state | 1 | [31 x 1] | Unrestricted | |
state | float* | state | 1 | [66 x 1] | Unrestricted | |
hardware_specific_struct_pointer | void * | state | 1 | Unrestricted |
Pins
Input Pins
Name: in
Description: audio input
...
Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: out
Description: audio output
Data type: float
MATLAB Usage
File Name: fir_smoothed_module.m
...