lib/gl_anyhash_primes.h

   1 /* Table of primes, for use by hash tables.
   2    Copyright (C) 2006, 2009-2024 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2006.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Array of primes, approximately in steps of factor 1.2.
  19    This table was computed by executing the Common Lisp expression
  20      (dotimes (i 244) (format t "nextprime(~D)~%" (ceiling (expt 1.2d0 i))))
  21    and feeding the result to PARI/gp.  */
  22 static const size_t primes[] =
  23   {
  24     11, 13, 17, 19, 23, 29, 37, 41, 47, 59, 67, 83, 97, 127, 139, 167, 199,
  25     239, 293, 347, 419, 499, 593, 709, 853, 1021, 1229, 1471, 1777, 2129, 2543,
  26     3049, 3659, 4391, 5273, 6323, 7589, 9103, 10937, 13109, 15727, 18899,
  27     22651, 27179, 32609, 39133, 46957, 56359, 67619, 81157, 97369, 116849,
  28     140221, 168253, 201907, 242309, 290761, 348889, 418667, 502409, 602887,
  29     723467, 868151, 1041779, 1250141, 1500181, 1800191, 2160233, 2592277,
  30     3110741, 3732887, 4479463, 5375371, 6450413, 7740517, 9288589, 11146307,
  31     13375573, 16050689, 19260817, 23112977, 27735583, 33282701, 39939233,
  32     47927081, 57512503, 69014987, 82818011, 99381577, 119257891, 143109469,
  33     171731387, 206077643, 247293161, 296751781, 356102141, 427322587,
  34     512787097, 615344489, 738413383, 886096061, 1063315271, 1275978331,
  35     1531174013, 1837408799, 2204890543UL, 2645868653UL, 3175042391UL,
  36     3810050851UL,
  37 #if SIZE_MAX > 4294967295UL
  38     4572061027UL, 5486473229UL, 6583767889UL, 7900521449UL, 9480625733UL,
  39     11376750877UL, 13652101063UL, 16382521261UL, 19659025513UL, 23590830631UL,
  40     28308996763UL, 33970796089UL, 40764955463UL, 48917946377UL, 58701535657UL,
  41     70441842749UL, 84530211301UL, 101436253561UL, 121723504277UL,
  42     146068205131UL, 175281846149UL, 210338215379UL, 252405858521UL,
  43     302887030151UL, 363464436191UL, 436157323417UL, 523388788231UL,
  44     628066545713UL, 753679854847UL, 904415825857UL, 1085298991109UL,
  45     1302358789181UL, 1562830547009UL, 1875396656429UL, 2250475987709UL,
  46     2700571185239UL, 3240685422287UL, 3888822506759UL, 4666587008147UL,
  47     5599904409713UL, 6719885291641UL, 8063862349969UL, 9676634819959UL,
  48     11611961783951UL, 13934354140769UL, 16721224968907UL, 20065469962669UL,
  49     24078563955191UL, 28894276746229UL, 34673132095507UL, 41607758514593UL,
  50     49929310217531UL, 59915172260971UL, 71898206713183UL, 86277848055823UL,
  51     103533417666967UL, 124240101200359UL, 149088121440451UL, 178905745728529UL,
  52     214686894874223UL, 257624273849081UL, 309149128618903UL, 370978954342639UL,
  53     445174745211143UL, 534209694253381UL, 641051633104063UL, 769261959724877UL,
  54     923114351670013UL, 1107737222003791UL, 1329284666404567UL,
  55     1595141599685509UL, 1914169919622551UL, 2297003903547091UL,
  56     2756404684256459UL, 3307685621107757UL, 3969222745329323UL,
  57     4763067294395177UL, 5715680753274209UL, 6858816903929113UL,
  58     8230580284714831UL, 9876696341657791UL, 11852035609989371UL,
  59     14222442731987227UL, 17066931278384657UL, 20480317534061597UL,
  60     24576381040873903UL, 29491657249048679UL, 35389988698858471UL,
  61     42467986438630267UL, 50961583726356109UL, 61153900471627387UL,
  62     73384680565952851UL, 88061616679143347UL, 105673940014972061UL,
  63     126808728017966413UL, 152170473621559703UL, 182604568345871671UL,
  64     219125482015045997UL, 262950578418055169UL, 315540694101666193UL,
  65     378648832921999397UL, 454378599506399233UL, 545254319407679131UL,
  66     654305183289214771UL, 785166219947057701UL, 942199463936469157UL,
  67     1130639356723763129UL, 1356767228068515623UL, 1628120673682218619UL,
  68     1953744808418662409UL, 2344493770102394881UL, 2813392524122873857UL,
  69     3376071028947448339UL, 4051285234736937517UL, 4861542281684325481UL,
  70     5833850738021191727UL, 7000620885625427969UL, 8400745062750513217UL,
  71     10080894075300616261UL, 12097072890360739951UL, 14516487468432885797UL,
  72     17419784962119465179UL,
  73 #endif
  74     SIZE_MAX /* sentinel, to ensure the search terminates */
  75   };
  76
  77 /* Returns a suitable prime >= ESTIMATE.  */
  78 static size_t
  79 next_prime (size_t estimate)
  80 {
  81   size_t i;
  82
  83   for (i = 0; i < sizeof (primes) / sizeof (primes[0]); i++)
  84     if (primes[i] >= estimate)
  85       return primes[i];
  86   return SIZE_MAX; /* not a prime, but better than nothing */
  87 }