5.5.7 FIRLattice

Description

FIRLattice uses a lattice structure implementation to apply an FIR filter to the sequence of source samples. It then places the results in the sequence of the destination samples and updates the delay values.

Prototype

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

Arguments

Return

Pointer to the base address of the destination sample.

Remarks

Number of the filter coefficients is M.

Coefficients, h[m], defined in 0 ≤ m < M, are not implemented as a circular modulo buffer.

Delay, d[m], defined in 0 ≤ m < M, are not implemented as a circular modulo buffer.

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

• firlatt_aa.s

Cycle counts for PIC32A:

(*All values with numCoeffs = 32)

System resource usage

• W0…W7 - used, not restored
• W8…W10 - saved, used, restored
• ACCA - used, not restored
• CORCON - saved, used, restored
• REPEAT instruction(s) usage – None