Dependency on fenv.h makes float HW use with libm impossible

[laurencelundblade]

Dependency on fenv.h makes float HW use with libm impossible

[laurencelundblade]

See #116

[laurencelundblade]

thanks for the comment. I will look into it, but it will take a week or so.

[laurencelundblade]

I will keep looking at it, but what happened when you defined QCBOR_DISABLE_FLOAT_HW_USE?

With QCBOR_DISABLE_FLOAT_HW_USE it should compile and run and be able to decode floating point numbers. What it can't do is convert floating point to integer, double to float and handle floating point dates. Most of these are pretty uncommon needs.

This only disables QCBOR's use of HW floating point. Your application can still use it.

Encoding and decoding CBOR floating point doesn't require floating point HW or even a library. It's essentially a cast of an int * to a float *. A good compiler should be able to do this without floating point library or HW.

[DusterTheFirst]

That does make sense and fits with what I found. In my opinion the functions that require fenv.h should probbably be removed if the QCBOR_DISABLE_FLOAT_HW_USE define is added as to prevent users from accidentally using them and getting weird crashes at run time. The documentation could also explain in further detail the functions that are disabled with the addition of QCBOR_DISABLE_FLOAT_HW_USE. Other than that this seems to be less of a problem than I thought of it at first, since its just those specific niche functioins which are impacted.

[laurencelundblade]

Yes, agree with you on the QCBOR_DISABLE_FLOAT_HW_USE documentation.I tried reading the documentation (that I wrote) to understand, but had to read the source code (that I wrote) to figure it out. :-)

I believe the functions that need fenv.h will return error codes when QCBOR_DISABLE_FLOAT_HW_USE is defined. They still do useful stuff even with QCBOR_DISABLE_FLOAT_HW_USE so they shouldn't be removed.

I will update the documentation and do some more cross-checking in the next week or so.

Thanks very much for filing the issue and checking back!

[laurencelundblade]

Thanks for the review!