kernel: fix RandomIntegerMT on 64 bit big endian

Fixes #2292
gap-system · Jul 10, 2018 · 1e4d544 · 1e4d544
1 parent eb6a367
commit 1e4d544
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Showing 4 changed files with 124 additions and 151 deletions.
diff --git a/src/integer.c b/src/integer.c
@@ -2655,7 +2655,7 @@ Obj FuncRandomIntegerMT(Obj self, Obj mtstr, Obj nrbits)
 {
   Obj res;
   Int i, n, q, r, qoff, len;
-  UInt4 *mt, rand;
+  UInt4 *mt;
   UInt4 *pt;
   while (! IsStringConv(mtstr)) {
      mtstr = ErrorReturnObj(
@@ -2707,14 +2707,21 @@ Obj FuncRandomIntegerMT(Obj self, Obj mtstr, Obj nrbits)
      pt = (UInt4*) ADDR_INT(res);
      mt = (UInt4*) CHARS_STRING(mtstr);
      for (i = 0; i < qoff; i++, pt++) {
-       rand = (UInt4) nextrandMT_int32(mt);
-       *pt = rand;
+       *pt = nextrandMT_int32(mt);
      }
      if (r != 0) {
        /* we generated too many random bits -- chop of the extra bits */
        pt = (UInt4*) ADDR_INT(res);
        pt[qoff-1] = pt[qoff-1] & ((UInt4)(-1) >> (32-r));
      }
+#if defined(SYS_IS_64_BIT) && defined(WORDS_BIGENDIAN)
+     // swap the halves of the 64bit words to match the
+     // little endian resp. 32 bit versions of this code
+     pt = (UInt4 *)ADDR_INT(res);
+     for (i = 0; i < qoff; i += 2, pt += 2) {
+       SWAP(UInt4, pt[0], pt[1]);
+     }
+#endif
      /* shrink bag if necessary */
      res = GMP_NORMALIZE(res);
      /* convert result if small int */

diff --git a/tst/test32bit/randlist.tst b/tst/test32bit/randlist.tst
diff --git a/tst/test64bit/randlist.tst b/tst/test64bit/randlist.tst
diff --git a/tst/testinstall/randlist.tst b/tst/testinstall/randlist.tst
@@ -0,0 +1,114 @@
+#############################################################################
+##
+#W  randlist.tst                   GAP library                Frank Lübeck
+##
+##
+#Y  Copyright (C)  2016, The GAP Group
+##
+gap> START_TEST("randlist.tst");
+gap> l4 := [1..2^28-1];
+[ 1 .. 268435455 ]
+gap> l8 := [1..2^60-1];
+[ 1 .. 1152921504606846975 ]
+gap> bits := Concatenation([27..33],[59..65],[95..97],[127..129]);;
+
+#
+gap> Reset(GlobalMersenneTwister, 1);;
+gap> List(bits,    i-> Random(1, 2^i));
+[ 18829054, 164251624, 474614219, 233454245, 213348187, 3257085298, 
+  1185099587, 100418839541388781, 78936154011671244, 1951632504588564735, 
+  1891846953557814001, 7380160538170766753, 4588549330382399543, 
+  20212399778158554723, 25871717046293081269812882956, 
+  74959154262646398646743466671, 52390258479956963774859779424, 
+  46150081993482768205533540973984006122, 
+  264304607032107166297612477092494666822, 
+  369126435272860177990538082224405421325 ]
+gap> List([1..10], i-> Random(1, 10^(3*i)));
+[ 796, 488110, 337484392, 594009012741, 658311342730164, 718543835420643146, 
+  192531588881827984252, 93448310516637261223301, 897306488169252919346512382,
+  373729190135314870329223545530 ]
+gap> List([1..10], i-> Random(l4));
+[ 143468941, 48373072, 9645662, 124739889, 124982356, 178658837, 173118677, 
+  117495931, 138389463, 242860897 ]
+gap> List([1..10], i-> Random(l8));
+[ 347927869732747975, 519413397450930047, 898055001130687869, 
+  163763776991392067, 969052338240557373, 1038155658715349861, 
+  493205527438070762, 28433991423533450, 173244587732492565, 
+  990629399330982901 ]
+
+#
+gap> Reset(GlobalRandomSource, 1);;
+gap> List(bits,    i-> Random(GlobalRandomSource, 1, 2^i));
+[ 128287824, 93339996, 497514298, 126333050, 888008348, 3272686668, 
+  3284765239, 246384569571494206, 899121525533970334, 2058504735678170118, 
+  1295847095154625366, 1831951483667165481, 12413749580545794189, 
+  21112300994467179461, 16479214171808335931562195799, 
+  47077177305952446651710749862, 93051612446083908105560589039, 
+  17595829529914834395994704246711425132, 
+  189028623575818650885511742806844572497, 
+  442802932679156364466206827982691923819 ]
+gap> List([1..10], i-> Random(GlobalRandomSource, 1, 10^(3*i)));
+[ 292, 540747, 68367363, 782766307890, 207951565811836, 269515013492647614, 
+  168133019703503347058, 46702024622849426851426, 498676940076039327334874754,
+  960893403060023160487783291143 ]
+gap> List([1..10], i-> Random(GlobalRandomSource, l4));
+[ 190962548, 17964291, 180726950, 185199085, 213556766, 109018187, 55718740, 
+  216423086, 151137000, 48013178 ]
+gap> List([1..10], i-> Random(GlobalRandomSource, l8));
+[ 1128201256618036672, 890212987711716841, 228981350846997556, 
+  962603471308182302, 697651637792723842, 464389630980588785, 
+  463611844822187319, 195151234274091472, 339385016873630147, 
+  670406272576191605 ]
+
+#
+gap> rs := RandomSource(IsMersenneTwister, 1);
+<RandomSource in IsMersenneTwister>
+gap> List(bits,    i-> Random(rs, 1, 2^i));
+[ 18829054, 164251624, 474614219, 233454245, 213348187, 3257085298, 
+  1185099587, 100418839541388781, 78936154011671244, 1951632504588564735, 
+  1891846953557814001, 7380160538170766753, 4588549330382399543, 
+  20212399778158554723, 25871717046293081269812882956, 
+  74959154262646398646743466671, 52390258479956963774859779424, 
+  46150081993482768205533540973984006122, 
+  264304607032107166297612477092494666822, 
+  369126435272860177990538082224405421325 ]
+gap> List([1..10], i-> Random(rs, 1, 10^(3*i)));
+[ 796, 488110, 337484392, 594009012741, 658311342730164, 718543835420643146, 
+  192531588881827984252, 93448310516637261223301, 897306488169252919346512382,
+  373729190135314870329223545530 ]
+gap> List([1..10], i-> Random(rs, l4));
+[ 143468941, 48373072, 9645662, 124739889, 124982356, 178658837, 173118677, 
+  117495931, 138389463, 242860897 ]
+gap> List([1..10], i-> Random(rs, l8));
+[ 347927869732747975, 519413397450930047, 898055001130687869, 
+  163763776991392067, 969052338240557373, 1038155658715349861, 
+  493205527438070762, 28433991423533450, 173244587732492565, 
+  990629399330982901 ]
+
+#
+gap> rs := RandomSource(IsGAPRandomSource, 1);
+<RandomSource in IsGAPRandomSource>
+gap> List(bits,    i-> Random(rs, 1, 2^i));
+[ 128287824, 93339996, 497514298, 126333050, 888008348, 3272686668, 
+  3284765239, 246384569571494206, 899121525533970334, 2058504735678170118, 
+  1295847095154625366, 1831951483667165481, 12413749580545794189, 
+  21112300994467179461, 16479214171808335931562195799, 
+  47077177305952446651710749862, 93051612446083908105560589039, 
+  17595829529914834395994704246711425132, 
+  189028623575818650885511742806844572497, 
+  442802932679156364466206827982691923819 ]
+gap> List([1..10], i-> Random(rs, 1, 10^(3*i)));
+[ 292, 540747, 68367363, 782766307890, 207951565811836, 269515013492647614, 
+  168133019703503347058, 46702024622849426851426, 498676940076039327334874754,
+  960893403060023160487783291143 ]
+gap> List([1..10], i-> Random(rs, l4));
+[ 190962548, 17964291, 180726950, 185199085, 213556766, 109018187, 55718740, 
+  216423086, 151137000, 48013178 ]
+gap> List([1..10], i-> Random(rs, l8));
+[ 1128201256618036672, 890212987711716841, 228981350846997556, 
+  962603471308182302, 697651637792723842, 464389630980588785, 
+  463611844822187319, 195151234274091472, 339385016873630147, 
+  670406272576191605 ]
+
+#
+gap> STOP_TEST( "randlist.tst", 1);