Torbjörn Granlund wrote on 2020-06-02 11:22:
Surely the field _lc could be be renamed to something less confusing without dire compatibility consequences. :-)
Since it was still used like that for the backwards-compatible generator, and access was done through the macros anyway, this was regarded as unnecessary beyond the comment.
The plan was to get rid of the struct issues in the next ABI breakage, but I guess no one took note of that with respect to the generators, or at least no one did anything about it (we've broken the ABI since GMP 4.0.1, right?) What breakage happened for 4.0.1?
Sorry, my wording was a bit confusing. I mean, we've broken the ABI at some point between 4.0.1 and now, right? 4.0.1 is the first version where I worked on the patch. I remember Kevin mentioning a list of changes to make in case of an ABI incompatible release, but I never saw that list until 2012. This thread talks about this kind of cleanup and mentions a list. https://gmplib.org/list-archives/gmp-devel/2012-June/002373.html The list is here: https://gmplib.org/devel/incompatibility Cleaning up the random state struct is in the list, but it needs a more extensive cleanup than mentioned there, because the function pointers are allocated separately, which is a waste.
I'm not too sure why I removed gmp_randinit_lc, but something about it being broken rings a bell, so it's possible that Kevin told me to do that. It's strange, but I cannot recall the reasons either.
I don't think it was ever documented, so it was probably in the works and planned, but considered obsolete later, and since it wasn't documented, it was removed.
I don't know for sure why gmp_randinit was not adapted to the new generators. Probably Kevin told me to do that but I don't remember the rationale. Perhaps it was to avoid more code than necessary to be pulled into a user binary?
Very likely, yes.
Unfortunately, Mersenne Twister uses mpz, and I am not saying that that was a bad choice when you implemented it.
It's not used if you don't call gmp_randseed[_ui](). gmp_randinit_mt includes a table with the initial state in order to avoid calling it. The gmp_randseed interface itself needs mpz.
But in order to provide reentrant mpn PRNG functions, we either rewrite the relevant parts of MT to use mpn, or exclude it from a new mpn PRNG interface.
As Marco said, this is solved by using XXTEA for seeding. _______________________________________________ gmp-devel mailing list gmp-devel@gmplib.org https://gmplib.org/mailman/listinfo/gmp-devel
