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Project Ne10
An Open Optimized Software Library Project for the ARM Architecture
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Modules | |
Finite Impulse Response (FIR) Interpolator | |
Finite Impulse Response (FIR) Lattice Filters | |
Finite Impulse Response (FIR) Sparse Filters | |
Infinite Impulse Response (IIR) Lattice Filters | |
Functions | |
ne10_result_t | ne10_iir_lattice_init_float (ne10_iir_lattice_instance_f32_t *S, ne10_uint16_t numStages, ne10_float32_t *pkCoeffs, ne10_float32_t *pvCoeffs, ne10_float32_t *pState, ne10_uint32_t blockSize) |
Initialization function for the floating-point IIR lattice filter. More... | |
void | ne10_iir_lattice_float_c (const ne10_iir_lattice_instance_f32_t *S, ne10_float32_t *pSrc, ne10_float32_t *pDst, ne10_uint32_t blockSize) |
Processing function for the floating-point IIR lattice filter. More... | |
void | ne10_fir_decimate_float_c (const ne10_fir_decimate_instance_f32_t *S, ne10_float32_t *pSrc, ne10_float32_t *pDst, ne10_uint32_t blockSize) |
Processing function for the floating-point FIR decimator. More... | |
Variables | |
void(* | ne10_iir_lattice_float )(const ne10_iir_lattice_instance_f32_t *S, ne10_float32_t *pSrc, ne10_float32_t *pDst, ne10_uint32_t blockSize) |
M
, the signal should be prefiltered by a lowpass filter with a normalized cutoff frequency of 1/M
in order to prevent aliasing distortion. The user of the function is responsible for providing the filter coefficients.The FIR decimator functions provided in the CMSIS DSP Library combine the FIR filter and the decimator in an efficient manner. Instead of calculating all of the FIR filter outputs and discarding M-1
out of every M
, only the samples output by the decimator are computed. The functions operate on blocks of input and output data. pSrc
points to an array of blockSize
input values and pDst
points to an array of blockSize/M
output values. In order to have an integer number of output samples blockSize
must always be a multiple of the decimation factor M
.
The library provides functions for floating-point data types.
y[n] = b[0] * x[n] + b[1] * x[n-1] + b[2] * x[n-2] + ...+ b[numTaps-1] * x[n-numTaps+1]where,
b[n]
are the filter coefficients. pCoeffs
points to a coefficient array of size numTaps
. Coefficients are stored in time reversed order. {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
pState
points to a state array of size numTaps + blockSize - 1
. Samples in the state buffer are stored in the order: {x[n-numTaps+1], x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2]....x[0], x[1], ..., x[blockSize-1]}The state variables are updated after each block of data is processed, the coefficients are untouched.
*ne10_fir_decimate_instance_f32_t S = {M, numTaps, pCoeffs, pState};where
M
is the decimation factor; numTaps
is the number of filter coefficients in the filter; pCoeffs
is the address of the coefficient buffer; pState
is the address of the state buffer. Be sure to set the values in the state buffer to zeros when doing static initialization.void ne10_fir_decimate_float_c | ( | const ne10_fir_decimate_instance_f32_t * | S, |
ne10_float32_t * | pSrc, | ||
ne10_float32_t * | pDst, | ||
ne10_uint32_t | blockSize | ||
) |
Processing function for the floating-point FIR decimator.
[in] | *S | points to an instance of the floating-point FIR decimator structure. |
[in] | *pSrc | points to the block of input data. |
[out] | *pDst | points to the block of output data. |
[in] | blockSize | number of input samples to process per call. |
Definition at line 452 of file NE10_fir.c.
void ne10_iir_lattice_float_c | ( | const ne10_iir_lattice_instance_f32_t * | S, |
ne10_float32_t * | pSrc, | ||
ne10_float32_t * | pDst, | ||
ne10_uint32_t | blockSize | ||
) |
Processing function for the floating-point IIR lattice filter.
[in] | *S | points to an instance of the floating-point IIR lattice structure. |
[in] | *pSrc | points to the block of input data. |
[out] | *pDst | points to the block of output data. |
[in] | blockSize | number of samples to process. |
Definition at line 118 of file NE10_iir.c.
ne10_result_t ne10_iir_lattice_init_float | ( | ne10_iir_lattice_instance_f32_t * | S, |
ne10_uint16_t | numStages, | ||
ne10_float32_t * | pkCoeffs, | ||
ne10_float32_t * | pvCoeffs, | ||
ne10_float32_t * | pState, | ||
ne10_uint32_t | blockSize | ||
) |
Initialization function for the floating-point IIR lattice filter.
[in] | *S | points to an instance of the floating-point IIR lattice structure. |
[in] | numStages | number of stages in the filter. |
[in] | *pkCoeffs | points to the reflection coefficient buffer. The array is of length numStages. |
[in] | *pvCoeffs | points to the ladder coefficient buffer. The array is of length numStages+1. |
[in] | *pState | points to the state buffer. The array is of length numStages+blockSize. |
[in] | blockSize | number of samples to process. |
Definition at line 45 of file NE10_iir_init.c.