Overview
Sparse FIR filter which works together with the DelayStateWriter module
Discussion
This module implements a sparse FIR filter which is also known as a tapped delay line. This module stores only the coefficients and delay times and works in conjunction with an upstram delay_state_writer_module.m. The delay_state_writer_module.m holds the state variables and can be shared by multiple FIRSpareReaderModules.
You need to make sure that the maximum tapped delay time does not exceed the allocated size of the upstream state buffer. No checking is made at run-time that this is the case.
The module only outputs a mono channel of data and the output blockSize must be a multiple of 8 samples. This last condition is checked by the module's prebuild function.
Type Definition
typedef struct _ModuleFIRSparseReader
{
ModuleInstanceDescriptor instance; // Common Audio Weaver module instance structure
INT32 numTaps; // Number of non-zero coefficients (taps) in the filter
INT32 dswObjectID; // Object ID of the upstream DelayStateWriter module
INT32* tapDelay; // Current delay per tap
INT32* tapDelayTarget; // Current delay per tap
FLOAT32* tapCoeffs; // Coefficient applied to each tap output
void * dswObjectPtr; // Points to the upstream DelayStateWriter module
} ModuleFIRSparseReaderClass;
Variables
Properties
Name | Type | Usage | isHidden | Default value | Range | Units |
numTaps | int | const | 0 | 20 | Unrestricted | |
dswObjectID | int | state | 1 | -1 | Unrestricted | |
tapDelay | int* | parameter | 0 | [20 x 1] | Unrestricted | samples |
tapDelayTarget | int* | state | 0 | [21 x 1] | Unrestricted | samples |
tapCoeffs | float* | parameter | 0 | [20 x 1] | Unrestricted | |
dswObjectPtr | void * | state | 1 | Unrestricted |
Pins
Input Pins
Name: ID
Description: audio input
Data type: int
Channel range: 1
Block size range: 1
Sample rate range: Unrestricted
Complex support: Real
Output Pins
Name: out
Description: audio output
Data type: float
MATLAB Usage
File Name: fir_sparse_reader_module.m
M = fir_sparse_reader_module(NAME, NUMTAPS, BLOCKSIZE, SAMPLERATE)
Creates a sparse FIR filter which is equivalent to a multi-tap time
delay in which the outputs are weighted and summed. This module works
in conjunction with the delay_state_writer_module.m. The "writer"
module stores the circular state buffer while this "reader" module
does the actual processing. The "writer" module output is a pointer
to its instance structure. The "reader" module uses the instance
pointer to read data out of the state buffer.
This module can only process a single mono channel of data.
Arguments:
NAME - name of the module.
NUMTAPS - number of taps
BLOCKSIZE - output block size (number of samples to generate).
If this is empty then we use the blockSize from the system
input. By default, BLOCKSIZE = [].
SAMPLERATE - sample rate of the output data. If this is empty
then we use the sample rate of the first input pin of the
containing system. By default, SAMPLERATE = [].