Conditions for Code Replacement of DSP Blocks with QHL

Each DSP block (DSP System Toolbox™) 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 blocks only when you set specific properties, as indicated in the following table:

DSP BlockInput RequirementsParameter RequirementsEquivalent Functions in Replacement
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
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

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)

    The maximum supported FFT length is 512.

  • 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

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

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

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.

See Also

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