grub-core/tests/div_test.c

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (C) 2013 Free Software Foundation, Inc.
   4  *
   5  *  GRUB is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  GRUB 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 General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <grub/test.h>
  20 #include <grub/dl.h>
  21 #include <grub/misc.h>
  22
  23 GRUB_MOD_LICENSE ("GPLv3+");
  24
  25 static grub_uint64_t vectors[][2] = {
  26   { 0xffffffffffffffffULL, 1},
  27   { 1, 0xffffffffffffffffULL},
  28   { 0xffffffffffffffffULL, 0xffffffffffffffffULL},
  29   { 1, 1 },
  30   { 2, 1 }
  31 };
  32
  33 static void
  34 test32 (grub_uint32_t a, grub_uint32_t b)
  35 {
  36   grub_uint64_t q, r;
  37   q = grub_divmod64 (a, b, &r);
  38   grub_test_assert (r < b, "remainder is larger than dividend: 0x%llx %% 0x%llx = 0x%llx",
  39                     (long long) a, (long long) b, (long long) r);
  40   grub_test_assert (q * b + r == a, "division doesn't satisfy base property: 0x%llx * 0x%llx + 0x%llx != 0x%llx", (long long) q, (long long) b, (long long) r,
  41                     (long long) a);
  42   /* Overflow check.  */
  43   grub_test_assert ((q >> 32) == 0,
  44                     "division overflow in 0x%llx, 0x%llx", (long long) a, (long long) b);
  45   grub_test_assert ((r >> 32) == 0,
  46                     "division overflow in 0x%llx, 0x%llx", (long long) a, (long long) b);
  47   /* q * b + r is at most:
  48      0xffffffff * 0xffffffff + 0xffffffff = 0xffffffff00000000
  49      so no overflow
  50    */
  51   grub_test_assert (q == (a / b),
  52                     "C compiler division failure in 0x%llx, 0x%llx", (long long) a, (long long) b);
  53   grub_test_assert (r == (a % b),
  54                     "C compiler modulo failure in 0x%llx, 0x%llx", (long long) a, (long long) b);
  55 }
  56
  57 static void
  58 test64 (grub_uint64_t a, grub_uint64_t b)
  59 {
  60   grub_uint64_t q, r;
  61   grub_uint64_t x1, x2;
  62   q = grub_divmod64 (a, b, &r);
  63   grub_test_assert (r < b, "remainder is larger than dividend: 0x%llx %% 0x%llx = 0x%llx",
  64                     (long long) a, (long long) b, (long long) r);
  65   grub_test_assert (q * b + r == a, "division doesn't satisfy base property: 0x%llx * 0x%llx + 0x%llx != 0x%llx", (long long) q, (long long) b, (long long) r,
  66                     (long long) a);
  67   /* Overflow checks.  */
  68   grub_test_assert ((q >> 32) * (b >> 32) == 0,
  69                     "division overflow in 0x%llx, 0x%llx", (long long) a, (long long) b);
  70   x1 = (q >> 32) * (b & 0xffffffff);
  71   grub_test_assert (x1 < (1LL << 32),
  72                     "division overflow in 0x%llx, 0x%llx", (long long) a, (long long) b);
  73   x1 <<= 32;
  74   x2 = (b >> 32) * (q & 0xffffffff);
  75   grub_test_assert (x2 < (1LL << 32),
  76                     "division overflow in 0x%llx, 0x%llx", (long long) a, (long long) b);
  77   x2 <<= 32;
  78   grub_test_assert (x1 <= ~x2,
  79                     "division overflow in 0x%llx, 0x%llx", (long long) a, (long long) b);
  80   x1 += x2;
  81   x2 = (q & 0xffffffff) * (b & 0xffffffff);
  82   grub_test_assert (x1 <= ~x2,
  83                     "division overflow in 0x%llx, 0x%llx", (long long) a, (long long) b);
  84   x1 += x2;
  85   grub_test_assert (x1 <= ~r,
  86                     "division overflow in 0x%llx, 0x%llx", (long long) a, (long long) b);
  87   x1 += r;
  88   grub_test_assert (a == x1,
  89                     "division overflow test failure in 0x%llx, 0x%llx", (long long) a, (long long) b);
  90 #if GRUB_TARGET_SIZEOF_VOID_P == 8
  91   grub_test_assert (q == (a / b),
  92                     "C compiler division failure in 0x%llx, 0x%llx", (long long) a, (long long) b);
  93   grub_test_assert (r == (a % b),
  94                     "C compiler modulo failure in 0x%llx, 0x%llx", (long long) a, (long long) b);
  95 #endif
  96 }
  97
  98 static void
  99 div_test (void)
 100 {
 101   grub_uint64_t a = 404, b = 7;
 102   grub_size_t i;
 103
 104   for (i = 0; i < ARRAY_SIZE (vectors); i++)
 105     {
 106       test64 (vectors[i][0], vectors[i][1]);
 107       test32 (vectors[i][0], vectors[i][1]);
 108     }
 109   for (i = 0; i < 40000; i++)
 110     {
 111       a = 17 * a + 13 * b;
 112       b = 23 * a + 29 * b;
 113       if (b == 0)
 114         b = 1;
 115       if (a == 0)
 116         a = 1;
 117       test64 (a, b);
 118       test32 (a, b);
 119
 120     }
 121 }
 122
 123 /* Register example_test method as a functional test.  */
 124 GRUB_FUNCTIONAL_TEST (div_test, div_test);