Library
AI Engine/DSP/Stream IO
Description
This block implements the stream-based FIR Symmetric Decimation filter targeted for AI Engines.
Parameters
- Main
-
- Input data type/Output data type
- Describes the type of individual data samples input to and output from the filter function. int16, cint16, int32, cint32, float, cfloat.
- Filter coefficients data type
- Describes the type of individual coefficients of
the filter taps. It should be one of int16, cint16, int32,
cint32, float, cfloat and must also satisfy the following
rules:
- Complex types are only supported when the Input/Output data type is also complex.
- 32-bit types are only supported when the Input/Output data type is also a 32-bit type.
- Filter coefficients data type must be an integer type if the Input/Output data type is an integer type.
- Filter coefficients data type must be a float type if the Input/Output data type is a float type.
- Specify filter coefficients via input port
- When this option is enabled, the tool allows you to specify reloadable filter coefficients via the input port.
- Filter coefficients
- This field should only be supplied for the first half of the filter length plus the center tap for odd lengths i.e., taps[] = {c0, c1, c2, ..., cN [, cCT]} where N = (FILTER_LENGTH)/2 and cCT is the center tap where FILTER_LENGTH is odd. For example, a 7-tap filter might use coeffs (1, 3, 2, 5, 2, 3, 1). This could be input as taps[]= {1,3,2,5} because the context of symmetry allows the remaining coefficients to be inferred.
- Filter length
- This is an unsigned integer which describes the number of taps in the filter. The filter length must be in the range 4 to 240 and must be an integer multiple of the decimation factor.
- Decimation factor
- An unsigned integer which describes the decimation factor of the filter. It must be in the range 2 to 3. For larger factors, use the FIR Asymmetric decimation filter.
- Input frame size (Number of samples)
- Describes the number of samples used as an input to the filter function. The number of values in the output window will be the input window size divided by decimation factor by virtue of the decimation factor.
- Scale output down by 2^
- Describes power of 2 shift down applied to the accumulation of FIR terms before output. It must be in range 0 to 61.
- Rounding mode
- Describes the selection of rounding to be
applied during the shift down stage of processing. The rounding
options are as follows:
- Floor (truncate)
- Ceiling
- Round to positive infinity
- Round to negative infinity
- Round symmetrical to infinity
- Round symmetrical to zero
- Round convergent to even
- Round convergent to odd
Modes 2 to 7 round to the nearest integer. They differ only in how they round for the value of 0.5.
- Number of parallel input/output (SSR)
- This parameter specifies the number of input (or output) ports and must be of the form 2^N, where N is a non-negative integer.
- Advanced
- Number of cascade stages:
- Specifies the number of cascade stages. The tool will guarantee the same.