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CCS/TMS320C6748: Usage of DSPLib with C6748

Deepak Joshi
Expert 1260 points
Part Number: TMS320C6748

Tool/software: Code Composer Studio

Hello,

I am using TMS320C6748 with dsplib_c64Px_3_4_0_0 (I purposely using the fixed point DSP lib as my Input will be fixed point so I am purposely avoiding to use dsplib_c674x_3_4_0_0). Now i have strange issue which i guess somebody have already seen. As i have lots of Complex computation and using _cmpyr and _cmpyr1 intrinsic so as per it my Real Samples are at MSB and Imag samples at LSB place (based on Sprugh7 section 4.60.

As i am using DSP_fft16x16 it says "The arrays for the complex input data x[], complex output data y[]  and twiddle factor w[] must be double word aligned. The input and output data are complex, with the real/imaginary components stored in adjacent locations in the array. The real components are stored at even array indices, and the imaginary  components are stored at odd array indices."

Now if i have to use _cmpyr real should be odd place but DSP_fft16x16 wants it to be in even place. I can do _rotl on the input data but that's not optimized approach. Can someone please tell me what i should do.

Also my project configuration is for _LITTLE_ENDIAN 

  • 0
    Guru 13202 points

    Hello!

    First, I had no experience wit C67 core, however I do have with C66. And when I look inside DSPLIB ver. 3.4 I there are as fixed point routines, so floating ones, like DSP_fft16x16 and DSPF_sp_fftSPxSP. So I guess there was no reason for you to stick with C64+. Next, in my installation of DSPLIB I see DSP_fft16x16_imre  routine, which operates on ImRe ordered samples rather than ReIm tradition. This might be of use in your case.

    Finally, if you get your data from external device through some programmable logic, like FPGA, it would cost nothing to your fellow FPGA engineer to swap those samples for you.

    Hope this helps.

  • 0 in reply to Victor Kazmirenko
    Expert 1260 points

    Thanks rrlagic,

    this solved my issue :D