gmp-impl.h assumes 32-bit unsigned int in fft_table_nk

Marco Bodrato bodrato at
Mon Dec 21 06:55:24 UTC 2015


Il Sab, 19 Dicembre 2015 5:09 am, Robert Baruch ha scritto:
> Oh, BTW, there is also the same problem in mpn/trialdiv.c:68, where
> gmp_primes_tab has a 24-bit field in an unsigned int.


unsigned int idx:24;	/* index of  first primes in dtab */

Makefile asks gen-trialdivtab to generate tables up-to 8000. There are
1007 primes smaller than 8000, so that the index should fit in 10 bits...

unsigned int np :8;	/* number of primes related to this entry */

The product of the smallest 31 primes requires more than 160 bits, much
larger than any limb size we currently support... np should fit in 5

With tighter definitions, both bit fields should fit a 16-bit integer.



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