Project Ne10
An open, optimized software library for the ARM architecture.

Functions  
ne10_result_t  ne10_fir_decimate_init_float (ne10_fir_decimate_instance_f32_t *S, ne10_uint16_t numTaps, ne10_uint8_t M, ne10_float32_t *pCoeffs, ne10_float32_t *pState, ne10_uint32_t blockSize) 
Initialization function for the floatingpoint FIR decimator. 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) 
Specific implementation of ne10_fir_decimate_float using plain C. More...  
void  ne10_fir_decimate_float_neon (const ne10_fir_decimate_instance_f32_t *S, ne10_float32_t *pSrc, ne10_float32_t *pDst, ne10_uint32_t blockSize) asm("ne10_fir_decimate_float_neon") 
Specific implementation of ne10_fir_decimate_float using NEON SIMD capabilities. More...  
Variables  
void(*  ne10_fir_decimate_float )(const ne10_fir_decimate_instance_f32_t *S, ne10_float32_t *pSrc, ne10_float32_t *pDst, ne10_uint32_t blockSize) 
Processing function for the floatingpoint FIR decimator. More...  
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 M1
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 floatingpoint data types.
y[n] = b[0] * x[n] + b[1] * x[n1] + b[2] * x[n2] + ...+ b[numTaps1] * x[nnumTaps+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[numTaps1], b[numTaps2], b[N2], ..., 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[nnumTaps+1], x[nnumTaps], x[nnumTaps1], x[nnumTaps2]....x[0], x[1], ..., x[blockSize1]}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  
) 
Specific implementation of ne10_fir_decimate_float using plain C.
Definition at line 429 of file NE10_fir.c.
void ne10_fir_decimate_float_neon  (  const ne10_fir_decimate_instance_f32_t *  S, 
ne10_float32_t *  pSrc,  
ne10_float32_t *  pDst,  
ne10_uint32_t  blockSize  
) 
Specific implementation of ne10_fir_decimate_float using NEON SIMD capabilities.
ne10_result_t ne10_fir_decimate_init_float  (  ne10_fir_decimate_instance_f32_t *  S, 
ne10_uint16_t  numTaps,  
ne10_uint8_t  M,  
ne10_float32_t *  pCoeffs,  
ne10_float32_t *  pState,  
ne10_uint32_t  blockSize  
) 
Initialization function for the floatingpoint FIR decimator.
[in,out]  *S  points to an instance of the floatingpoint FIR decimator structure. 
[in]  numTaps  number of coefficients in the filter. 
[in]  M  decimation factor. 
[in]  *pCoeffs  points to the filter coefficients. 
[in]  *pState  points to the state buffer. 
[in]  blockSize  number of input samples to process per call. 
blockSize
is not a multiple of M
.Description:
pCoeffs
points to the array of filter coefficients stored in time reversed order: {b[numTaps1], b[numTaps2], b[N2], ..., b[1], b[0]}
pState
points to the array of state variables. pState
is of length numTaps+blockSize1
words where blockSize
is the number of input samples passed to arm_fir_decimate_f32()
. M
is the decimation factor. Definition at line 98 of file NE10_fir_init.c.
void(* ne10_fir_decimate_float) (const ne10_fir_decimate_instance_f32_t *S, ne10_float32_t *pSrc, ne10_float32_t *pDst, ne10_uint32_t blockSize) 
Processing function for the floatingpoint FIR decimator.
[in]  *S  points to an instance of the floatingpoint 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. 
Points to ne10_fir_decimate_float_c or ne10_fir_decimate_float_neon.
Definition at line 168 of file NE10_init_dsp.c.