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Conditions for Code Replacement of DSP System Objects with HVX

DSP system objects (you will require DSP Toolbox installed) that can be used with the Support Package for Qualcomm Hexagon processors require specific conditions to allow code replacement with the Hexagon Vector Extension (HVX). You use this code replacement when generating C/C++ code from a model. The support package do not support any multi-rate DSP blocks in the Code Replacement Library (CRL). The Hexagon Vector Extension (HVX) supports these DSP system objects only when you set specific properties, as indicated in the following table:

 DSP System ObjectInput RequirementsParameter RequirementsEquivalent Functions in Replacement
1dsp.FIRFilter (DSP System Toolbox)

  • Real values.

  • single data type

  • Input frame length >= Filter length rounded to nearest multiple of 32

  • Structure: Direct Form.

  • NumeratorSource:: Property or Input port.

 mw_qhdsp_hvx_fir_af
2dsp.FFT (DSP System Toolbox)

  • Real values.

  • single data type

  • Input size must be in powers of 2

  • Real : 64, 128 ….

  • Complex: 32,64,...

  • FFTImplementation: Auto

  • BitReversedOutput: false

  • FFTLength : <same as input length > (If FFTLengthSource is set to Property)

  • Real FFT

    • mw_qhdsp_hvx_fft_gen_twiddles_real_acf

    • mw_qhdsp_hvx_r1dfft_af

  • Complex FFT

    • mw_qhdsp_hvx_fft_gen_twiddles_complex_acf

    • mw_qhdsp_hvx_c1dfft_af

3dsp.FFT (DSP System Toolbox)

  • single data type.

  • Complex input values.

  • Input size must be in powers of 2.

  • Real : 64, 128 ….

  • Complex: 32, 64...

  • FFT Length: same as input length (FFTLengthSource: is set to Property)

  • Bit reversed order: false

  • Real FFT

    • mw_qhdsp_hvx_fft_gen_twiddles_real_acf

    • mw_qhdsp_hvx_r1difft_af

  • Complex FFT

    • mw_qhdsp_hvx_fft_gen_twiddles_complex_acf

    • mw_qhdsp_hvx_c1difft_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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