Conditions for Code Replacement of DSP System Objects with QHL

Each DSP System object™ that can be used with the Embedded Coder^® 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 System object only when you set specific properties, as indicated in the following table:

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DSP System Object	Input Requirements	Parameter Requirements	Equivalent Functions in Replacement
dsp.FIRFilter (DSP System Toolbox)	Real values. single data type Input size must be even	Structure: Direct Form. NumeratorSource:: Property or Input port. Any frame-length if filter-length > 24. (or) 8 <= frame-length <=64 if 16<=filter length <=24	mw_qhdsp_fir_af
dsp.FIRDecimator (DSP System Toolbox)	Real values. single data type Input size must be even	Structure: Direct Form. NumeratorSource:: Property or Input port or Auto. Decimation Factor: 2,3,4 AllowArbitraryInputLength: false Decimation Factor: 2 or 3 AND FrameLength > 10 AND FilterLength >10.(or) Decimation Factor: 4 AND FilterLength < 40	mw_qhdsp_decim_af
dsp.FFT (DSP System Toolbox)	Real values. single data type Input size must be in powers of 2 Real : 16,32, …. Complex: 8,16,...	FFTImplementation: Auto BitReversedOutput: false FFTLength : <same as input length > (If FFTLengthSource is set to Property)	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
dsp.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 (FFTLengthSource: is set to Property) Bit reversed order: false	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
dsp.SOSFilter (DSP System Toolbox)	single data type. Real values.	Filter structure: Direct-form II Transposed Coefficient sources: Property / Input port HasScaleValues: True / False 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.