This routine implements a real all-pole IIR filter in lattice structure (AR lattice). The filter consists of nk lattice stages. Each stage requires one reflection coefficient k and one delay element b. The routine takes an input vector x[] and returns the filter output in y[]. Prior to the first call of the routine the delay elements in b[] should be set to zero. The input data may have to be pre-scaled to avoid overflow or achieve better SNR. The reflections coefficients lie in the range -1.0 < k < 1.0. The order of the coefficients is such that k[nk-1] corresponds to the first lattice stage after the input and k[0] corresponds to the last stage.
- Parameters
-
x[nx] | Input vector. |
nx | Length of input vector. |
k[nk] | Reflection coefficients. |
nk | Number of reflection coefficients/lattice stages. |
b[nk+1] | Delay line elements from previous call. Should be initialized to all zeros prior to the first call. |
y[nx] | Output vector. |
- Algorithm:
- DSPF_sp_iirlat_cn.c is the natural C equivalent of the optimized linear assembly code without restrictions. Note that the linear assembly code is optimized and restrictions may apply.
- Assumptions:
- nx > 0, nk is a multiple of 2 and >= 6.
Extraneous loads are allowed (80 bytes) before the start of array.
The arrays k and b are double-word aligned.
- Implementation Notes:
- Interruptibility: The code is interruptible.
Endian Support: The code supports both big and little endian modes.