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- Name: LATFIR2.ASM
- Type: Assembler Macro
- Version: 1.0
- Last Change: 8-Aug-86
-
- Description: Lattice FIR Filter Assembler Macro
-
- This macro implements a lattice fir filter using reflection coefficients.
- This implementation is similar to the filter LATFIR1 except that the
- modulo on the coefficients is equal to the filter order compared to
- LATFIR1 where the modulo is equal to the filter order plus one.
-
- It is possible to modify the LATFIR1 slightly such that the
- number of locations needed to store the filter coefficients
- is equal to the number of filter coefficients (note in the
- implementation of LATFIR1 there is an unused value).
- The filter macro is identical to the filter macro 'latfir1'
- except for the last instruction. The pointers R0
- and R4 are both adjusted by using dummy loads. The memory map is
- thus:
-
- R0 R4
- | |
- v v
- x: S1 S2 S3 Sx y: k1 k2 k3
-
- M0=3 (mod 4) M4=2 (mod 3)
-
- The modulo register for the coefficients is set equal to the
- number of filter coefficients minus one (the modulo register
- is set to the desired modulo minus one). See the example
- 'latfir2t' in the DSPLIB for an example of how to use this filter.
-