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| author | vlefevre <vlefevre@280ebfd0-de03-0410-8827-d642c229c3f4> | 2020-10-23 11:05:37 +0000 |
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| committer | vlefevre <vlefevre@280ebfd0-de03-0410-8827-d642c229c3f4> | 2020-10-23 11:05:37 +0000 |
| commit | c5e641dc3a4b8a6024a9bd410cc0b269947e0f5a (patch) | |
| tree | 49a28f4298d135c534e48c655eb47fecbe9d513f /src/invert_limb.h | |
| parent | 92c9d2b89aa3b560211b545bb1650e0c5f802e18 (diff) | |
| download | mpfr-c5e641dc3a4b8a6024a9bd410cc0b269947e0f5a.tar.gz | |
[src/invert_limb.h] Added a comment about r14171.
git-svn-id: https://scm.gforge.inria.fr/anonscm/svn/mpfr/trunk@14172 280ebfd0-de03-0410-8827-d642c229c3f4
Diffstat (limited to 'src/invert_limb.h')
| -rw-r--r-- | src/invert_limb.h | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/src/invert_limb.h b/src/invert_limb.h index 4a9930443..f72194797 100644 --- a/src/invert_limb.h +++ b/src/invert_limb.h @@ -74,7 +74,14 @@ static const unsigned short invert_limb_table[256] = 1055, 1053, 1051, 1049, 1047, 1044, 1042, 1040, 1038, 1036, 1034, 1032, 1030, 1028, 1026, 1024 }; -/* for 256 <= d9 < 512, invert_limb_table2[d9-256] = floor((2^19-3*2^8)/d9)^2 */ +/* for 256 <= d9 < 512, invert_limb_table2[d9-256] = floor((2^19-3*2^8)/d9)^2 + * + * Note: This table requires 4182025 to be representable in unsigned int, + * thus disallows 16-bit int, for instance. However, this code is under + * "#if GMP_NUMB_BITS == 64", and a system with int smaller than 32 bits + * should better be used with GMP_NUMB_BITS == 32 (or 16 if supported). + * This constraint is checked with MPFR_STAT_STATIC_ASSERT below. + */ static const unsigned int invert_limb_table2[256] = { 4182025, 4149369, 4116841, 4084441, 4052169, 4020025, 3992004, 3960100, 3932289, 3900625, 3873024, 3841600, 3814209, 3786916, 3755844, 3728761, 3701776, 3674889, |