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

Robert Baruch robert.c.baruch at
Sat Dec 19 04:09:05 UTC 2015

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.

On Fri, Dec 18, 2015 at 8:06 PM Robert Baruch <robert.c.baruch at>

> Thanks for the discussion! The fun thing is that I'll try to deal with
> integers on the order of 200 decimals (figure on the order of 700 bits). I
> think that mini-gmp is billed as "several orders of magnitude slower" than
> gmp on numbers over a few hundred bits, so I'd still like to see what gmp
> does (with --disable-fft).
> On Fri, Dec 18, 2015 at 7:50 AM Torbjörn Granlund <tg at> wrote:
>> Marc Glisse <marc.glisse at> writes:
>>   We have --disable-fft, maybe the code in gmp-impl.h could be protected
>>   by WANT_FFT. gmp_uint_least32_t also looks like it is unlikely to
>>   hurt, and we are already using it for other bitfields in the same
>>   file.
>>   Those changes could make sense whether we support 16 bit systems or not.
>> Agreed with both suggestions.  (Our usage of unsigned long as basetype
>> is not standards conformant, and it might not work on an environment
>> where int is just 2 bytes.)
>> --
>> Torbjörn
>> Please encrypt, key id 0xC8601622

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