5.5.2 FIR

Description

FIR applies an FIR filter to the sequence of source samples, places the results in the sequence of destination samples and updates the delay values.

Prototype

fractional* FIR (int numSamps, fractional* dstSamps, fractional* srcSamps, FIRStruct* filter);

Arguments


Parameters	Description
numSamps	Number of the input samples to filter (also N)
dstSamps	Pointer to the destination samples (also y)
srcSamps	Pointer to the source samples (also x)
filter	Pointer to the FIRStruct filter structure

Return

Pointer to the base address of the destination sample.

Remarks

Number of filter coefficients is M.

Coefficients, h[m], defined in 0 ≤ m < M, implemented as a circular increasing modulo buffer.

Delay, d[m], defined in 0 ≤ m < M, implemented as a circular increasing modulo buffer. The Delay vector must be placed in Y-Data space.

Source samples, x[n], defined in 0 ≤ n < N.

Destination samples, y[n], defined in 0 ≤ n < N.

(See also FIRStruct, FIRStructInit and FIRDelayInit.)

Source File

Cycle counts for PIC32A:


Source Vector Size	Cycles if coefficients in X-mem	Cycles if coefficients in P-mem
32	1222	3112
64	2376	6152
128	4676	12232
256	9288	24392
512	18500	48712
1024	36936	97352
2048	73796	194632

(*All values with numCoeffs = 32)

System resource usage