Conditions for Code Replacement of DSP Blocks with QHL

Each DSP blocks (DSP System Toolbox™) that can be used with the Support Package for Qualcomm Hexagon processors requires specific conditions to allow code replacement with the Qualcomm Hexagon Library (QHL). You use this code replacement when generating C code from a model. The Qualcomm Hexagon Library (QHL) supports these DSP blocks only when you set specific properties, as indicated in the following table:

	DSP Block	Input Requirements	Parameter Requirements	Equivalent Functions in Replacement
1	Discrete FIR Filter	Real values. `single` data type Input size must be even	Filter structure: `Direct Form`. Input processing: `Columns as channels (frame based)`. Coefficients source: `Dialog parameters` or `Input port`. Any frame-length if filter-length > 24. or 8 <= frame-length <=64 if 16<=filter length <=24	`mw_qhdsp_fir_af`
2	FIR Decimation (DSP System Toolbox)	Real values. `single` data type Input size must be even	Filter structure: `Direct Form`. Input processing: `Columns as channels (frame based)`. Coefficients source: `Dialog parameters` or `Auto`. Rate options: Enforce single-rate processing. Allow arbitrary frame length for fixed-size input signals: off Decimation Factor: 2,3,4 Decimation Factor: 2 or 3 AND Frame Length > 10 AND Filter Length >10. (or) Decimation Factor: 4 AND Filter Length < 40	`mw_qhdsp_decim_af`
3	FFT (DSP System Toolbox)	`single` data type. Input size must be in powers of 2. Real : 16,32, …. Complex: 8,16,...	FFT Length: same as input length (If Inherit FFT length from input dimensions: off) FFT implementation: Auto Divide output by FFT length: Off Output in bit reversed order: off	Real FFT `mw_qhdsp_fft_gen_twiddles_real_acf` `mw_qhdsp_acf_r1dfft_af` Complex FFT `mw_qhdsp_fft_gen_twiddles_complex_acf` `mw_qhdsp_c1dfft_acf`
4	IFFT (DSP System Toolbox)	`single` data type. Complex input values. Input size must be in powers of 2. Real : 32, 64 …. Complex: 16, 32...	FFT Length: same as input length (If Inherit FFT length from input dimensions: off) Input in bit reversed order: off	Real FFT `mw_qhdsp_fft_gen_twiddles_real_acf` `mw_qhdsp_af_r1difft_acf` Complex FFT `mw_qhdsp_fft_gen_twiddles_complex_acf` `mw_qhdsp_c1idfft_acf`
5	Biquad Filter (DSP System Toolbox)	`single` data type. Real values.	Filter structure: Direct-form II Transposed Input processing: Columns as channels (frame-based) Coefficient sources: Dialog Parameters, Input port All other parameters are supported.(scales, initial conditions etc) Number of sections: 2 or 3 AND "FrameLength >= 50 or Number of sections>= 4 AND FrameLength >= 9	`mw_qhdsp_iir_af`
6	Second-Order Section Filter (DSP System Toolbox)	`single` data type. Real values.	Filter structure: Direct-form II Transposed Input processing: Columns as channels (frame-based) Coefficient sources: Dialog Parameters, Input port All other parameters are supported.(scales, initial conditions etc) Number of sections: 2 or 3 AND FrameLength >= 50 or Number of sections>= 4 AND FrameLength >= 9	`mw_qhdsp_iir_af`

Note

Use only column-major layout for QHL/HVX replacements. For more information, see Row-Major and Column-Major Array Layouts.

Conditions for Code Replacement of DSP Blocks with QHL

See Also

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