Managing integer divide by zero checks in MATLAB R2016b codegen output

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JM 2017-11-13

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https://ww2.mathworks.cn/matlabcentral/answers/366716-managing-integer-divide-by-zero-checks-in-matlab-r2016b-codegen-output

评论： Birdman 2017-11-26

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When generating C code using codegen in at least MATLAB R2016b that contains integer divisions like:

out = uint32(a)/uint32(b)

an elaborate scheme to check for division by zero is implemented as follows in C:

if (b == 0U) {
  if (a == 0U) {
    out = 0U;
  } else {
    out = MAX_uint32_T;
  }
} else {
  // the actual division regular case
}

I would like to be able to tell codegen that these zero checks are not necessary and only output the commented line but I am not able to find a configuration option for this functionality.

I would like so see an option like SaturateOnIntegerOverflow that is able to turn off adding code for Inf special cases but for zero division.

A different option would be the ability to tell codegen what range of values to expect for various input parameters or values.

Are either of the two options above available?

I am using the regular MATLAB Coder Toolbox from the command line in MATLAB R2016b as follows:

configstruct = coder.config('mex'); % can be exe
configstruct.SomeOption1 = SomeValue1;
configstruct.SomeOption2 = SomeValue2;
codegen(...
  'SomeFunction.m',...
  '-config',configstruct,...
  'args',{...},...
);

The Embedded Coder Toolbox and Simulink are available to me if absolutely required.

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Birdman 2017-11-13

Why do you want to disable that check?

JM 2017-11-13

I would like to reduce ROM size and computation time using the knowlegde that the values to be divided by are always nonzero.

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回答（1 个）

Birdman 2017-11-13

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/366716-managing-integer-divide-by-zero-checks-in-matlab-r2016b-codegen-output#answer_290836

Go to Configuration Parameters->All Parameters and write Remove code that protects against division arithmetic exceptions. Its default value is off(unchecked). Make that on(checked).

To continue this story I could not find a way to use Simulink Coder to generate mex files from an .m file and still support this option. The option in question is only available when generating ERT files. :(

As a side note I could use many more of the code generation options presented in Simulink but not available in the command line code generator. :(