tests/test-round2.c

   1 /* Test of rounding to nearest, breaking ties away from zero.
   2    Copyright (C) 2007-2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Ben Pfaff <blp@gnu.org>, 2007.
  18    Heavily based on code by Bruno Haible. */
  19
  20 /* When this test fails on some platform, build it together with the gnulib
  21    module 'fprintf-posix' for optimal debugging output.  */
  22
  23 /* Get the two reference implementations of round under the names
  24    round_reference1 and round_reference2.
  25
  26    round.c will #include <config.h> for us. */
  27 #define FLOOR_BASED_ROUND round_reference1
  28 #define FLOOR_FREE_ROUND round_reference2
  29 #include "round.c"
  30
  31 #include <math.h>
  32 #include <float.h>
  33 #include <stdint.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36
  37 #ifdef USE_LONG_DOUBLE
  38 # error Long double not supported.
  39 #elif ! defined USE_FLOAT
  40 # include "isnand-nolibm.h"
  41 # define ISNAN isnand
  42 # define FUNCTION "round"
  43 # define DOUBLE_UINT uint64_t
  44 # define DOUBLE_BITS 64
  45 # define NUM_HIGHBITS 13
  46 # define NUM_LOWBITS 4
  47 #else /* defined USE_FLOAT */
  48 # include "isnanf-nolibm.h"
  49 # define ISNAN isnanf
  50 # define FUNCTION "roundf"
  51 # define DOUBLE_UINT uint32_t
  52 # define DOUBLE_BITS 32
  53 # define NUM_HIGHBITS 12
  54 # define NUM_LOWBITS 4
  55 #endif
  56
  57 /* Test for equality.  */
  58 static bool
  59 equal (const char *message, DOUBLE x, DOUBLE y0, DOUBLE y1)
  60 {
  61   if (ISNAN (y0) ? ISNAN (y1) : y0 == y1)
  62     return true;
  63   else
  64     {
  65 #if GNULIB_TEST_FPRINTF_POSIX
  66       fprintf (stderr, "%s: "FUNCTION"(%g(%a)) = %g(%a) or %g(%a)?\n",
  67                message, x, x, y0, y0, y1, y1);
  68 #endif
  69       return false;
  70     }
  71 }
  72
  73 /* Test the function for a given argument.  */
  74 static bool
  75 check (DOUBLE x)
  76 {
  77   DOUBLE ref1 = round_reference1 (x);
  78   DOUBLE ref2 = round_reference2 (x);
  79   DOUBLE result = ROUND (x);
  80
  81   /* If the reference implementations disagree, bail out immediately.  */
  82   if (!equal ("reference implementations disagree", x, ref1, ref2))
  83     exit (EXIT_FAILURE);
  84
  85   /* If the actual implementation is wrong, return an error code.  */
  86   return equal ("bad round implementation", x, ref1, result);
  87 }
  88
  89 int
  90 main (void)
  91 {
  92   DOUBLE_UINT highbits, lowbits;
  93   int error = 0;
  94   for (highbits = 0; highbits < (1 << NUM_HIGHBITS); highbits++)
  95     for (lowbits = 0; lowbits < (1 << NUM_LOWBITS); lowbits++)
  96       {
  97         /* Combine highbits and lowbits into a floating-point number,
  98            sign-extending the lowbits to DOUBLE_BITS-NUM_HIGHBITS bits.  */
  99         union { DOUBLE f; DOUBLE_UINT i; } janus;
 100         static_assert (sizeof janus.f == sizeof janus.i);
 101         janus.i = lowbits | (highbits << (DOUBLE_BITS - NUM_HIGHBITS));
 102         if (lowbits >> (NUM_LOWBITS - 1))
 103           janus.i |= ((DOUBLE_UINT) -1
 104                       >> (NUM_LOWBITS + NUM_HIGHBITS)
 105                       << NUM_LOWBITS);
 106         if (!check (janus.f))
 107           error = true;
 108       }
 109   return (error ? 1 : 0);
 110 }