Error: A cast between fixpt and floating point type is not supported

Question

Sandip Paul 2019-12-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/497679-error-a-cast-between-fixpt-and-floating-point-type-is-not-supported

回答： Kiran Kintali 2019-12-26

I am trying to convert my matlab code to HDL verilog code by HDL Coder. Fixed-Point Conversion shows no Error,but at the time HDL code Generation it show error that

" ErrorA cast between fixpt and floating point type is not supported, at Function 'cameraman_dwt_code1_fixpt' (#1.874.875), line 21, column 12."

My Fixed-Point Arithmatic code is-
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                          %
%           Generated by MATLAB 9.2 and Fixed-Point Designer 5.4           %
%                                                                          %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%#codegen
function xavg12 = cameraman_dwt_code1_fixpt(xr1)
fm = get_fimath();
[fmo_1,fmo_2,fmo_3,fmo_4] = dwt2(xr1,'db3');
xavg = fi(fmo_1, 0, 14, 5, fm);
xhr = fi(fmo_2, 1, 14, 43, fm);
xvr = fi(fmo_3, 1, 14, 43, fm);
xdig = fi(fmo_4, 0, 14, 83, fm);
x1=fi(xavg(1,1), 0, 14, 5, fm);        %#This line creates error at xavg(1,1) section(above mentiond on error- line21,coloumn 12)
xavg12=fi(x1, 0, 14, 5, fm);
end
function fm = get_fimath()
	fm = fimath('RoundingMethod', 'Floor',...
	     'OverflowAction', 'Wrap',...
	     'ProductMode','FullPrecision',...
	     'MaxProductWordLength', 128,...
	     'SumMode','FullPrecision',...
	     'MaxSumWordLength', 128);
end

####################### My function is->

function xavg12 = cameraman_dwt_code1(xr1)
[xavg,xhr,xvr,xdig] = dwt2(xr1,'db3');
x1=xavg(1,1);
xavg12=x1;

####################### My TestBench code is->

x=158;
xavg11=cameraman_dwt_code1(x);
disp(xavg11);

############# It is actually for an Image processing code but I want to test it only for a single pixel value.

Overall code output is 1.2392 for pixel or input value 158 which is acurate but still I can not solved the Fixed-Point Arithmatic code.

Please Help me.Thank you

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Walter Roberson 2019-12-21

I have not used the Fixed Point toolbox, only read a little about it.

At the moment I am concerned that possibly dwt2() is not being transformed to fixed point.

I wonder if it would help to switch to an integer wavelet? https://www.mathworks.com/help/wavelet/ug/lifting-method-for-constructing-wavelets.html#bs9j3kj

Sandip Paul 2019-12-21

Ok.Thank you very much.

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Answer 1

Kiran Kintali 2019-12-23

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https://ww2.mathworks.cn/matlabcentral/answers/497679-error-a-cast-between-fixpt-and-floating-point-type-is-not-supported#answer_407488

编辑：Kiran Kintali 2019-12-23

Hi Sandip,

The issue here is not related to fixed-point conversion; HDL Coder currently does not support dwt2 function out of the box for HDL code generation.

You need to rewrite dwt2_hdl(pixel_in) function to accomplish the algorithm on hardware.

Thanks

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Answer 2

Kiran Kintali 2019-12-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/497679-error-a-cast-between-fixpt-and-floating-point-type-is-not-supported#answer_407819

Hi Sandip,

Since dwt2 is not supported out of the box, please consider using core MATLAB to HDL features and implement dwt2_fpga.m using first principles. There is lot of material on the web related to this topic. https://tinyurl.com/s8flm5j

The previously mentioned links show you how to write good MATLAB suitable for HDL code generation.

Thanks