Mercurial > gnulib
annotate tests/test-floor2.c @ 40196:e63f5d3edab5
relocatable-prog: Update documentation.
* doc/relocatable-maint.texi (Supporting Relocation): Update to match
the recent changes.
| author | Bruno Haible <bruno@clisp.org> |
|---|---|
| date | Sun, 24 Feb 2019 01:49:15 +0100 |
| parents | b06060465f09 |
| children |
| rev | line source |
|---|---|
| 13974 | 1 /* Test of rounding towards negative infinity. |
|
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Paul Eggert <eggert@cs.ucla.edu>
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2 Copyright (C) 2007-2019 Free Software Foundation, Inc. |
| 13974 | 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 | |
| 19190 | 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
| 13974 | 16 |
| 17 /* Written by Bruno Haible <bruno@clisp.org>, 2007. */ | |
| 18 | |
| 19 /* When this test fails on some platform, build it together with the gnulib | |
| 20 module 'fprintf-posix' for optimal debugging output. */ | |
| 21 | |
| 22 #include <config.h> | |
| 23 | |
| 24 #include <math.h> | |
| 25 | |
| 26 #include <float.h> | |
| 27 #include <stdbool.h> | |
| 28 #include <stdint.h> | |
| 29 #include <stdio.h> | |
| 30 | |
| 31 #include "isnand-nolibm.h" | |
| 32 #include "macros.h" | |
| 33 | |
|
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34 /* MSVC with option -fp:strict refuses to compile constant initializers that |
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35 contain floating-point operations. Pacify this compiler. */ |
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36 #ifdef _MSC_VER |
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37 # pragma fenv_access (off) |
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38 #endif |
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39 |
| 13974 | 40 |
| 41 /* The reference implementation, taken from lib/floor.c. */ | |
| 42 | |
| 43 #define DOUBLE double | |
| 44 #define MANT_DIG DBL_MANT_DIG | |
| 45 #define L_(literal) literal | |
| 46 | |
| 47 /* 2^(MANT_DIG-1). */ | |
| 48 static const DOUBLE TWO_MANT_DIG = | |
| 49 /* Assume MANT_DIG <= 5 * 31. | |
| 50 Use the identity | |
| 51 n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5). */ | |
| 52 (DOUBLE) (1U << ((MANT_DIG - 1) / 5)) | |
| 53 * (DOUBLE) (1U << ((MANT_DIG - 1 + 1) / 5)) | |
| 54 * (DOUBLE) (1U << ((MANT_DIG - 1 + 2) / 5)) | |
| 55 * (DOUBLE) (1U << ((MANT_DIG - 1 + 3) / 5)) | |
| 56 * (DOUBLE) (1U << ((MANT_DIG - 1 + 4) / 5)); | |
| 57 | |
| 58 DOUBLE | |
| 59 floor_reference (DOUBLE x) | |
| 60 { | |
| 61 /* The use of 'volatile' guarantees that excess precision bits are dropped | |
| 62 at each addition step and before the following comparison at the caller's | |
| 63 site. It is necessary on x86 systems where double-floats are not IEEE | |
| 64 compliant by default, to avoid that the results become platform and compiler | |
| 65 option dependent. 'volatile' is a portable alternative to gcc's | |
| 66 -ffloat-store option. */ | |
| 67 volatile DOUBLE y = x; | |
| 68 volatile DOUBLE z = y; | |
| 69 | |
| 70 if (z > L_(0.0)) | |
| 71 { | |
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72 /* For 0 < x < 1, return +0.0 even if the current rounding mode is |
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73 FE_DOWNWARD. */ |
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74 if (z < L_(1.0)) |
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75 z = L_(0.0); |
| 13974 | 76 /* Avoid rounding errors for values near 2^k, where k >= MANT_DIG-1. */ |
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77 else if (z < TWO_MANT_DIG) |
| 13974 | 78 { |
| 79 /* Round to the next integer (nearest or up or down, doesn't matter). */ | |
| 80 z += TWO_MANT_DIG; | |
| 81 z -= TWO_MANT_DIG; | |
| 82 /* Enforce rounding down. */ | |
| 83 if (z > y) | |
| 84 z -= L_(1.0); | |
| 85 } | |
| 86 } | |
| 87 else if (z < L_(0.0)) | |
| 88 { | |
| 89 /* Work around ICC's desire to optimize denormal floats to 0. */ | |
| 90 if (z > -DBL_MIN) | |
| 91 return L_(-1.0); | |
| 92 /* Avoid rounding errors for values near -2^k, where k >= MANT_DIG-1. */ | |
| 93 if (z > - TWO_MANT_DIG) | |
| 94 { | |
| 95 /* Round to the next integer (nearest or up or down, doesn't matter). */ | |
| 96 z -= TWO_MANT_DIG; | |
| 97 z += TWO_MANT_DIG; | |
| 98 /* Enforce rounding down. */ | |
| 99 if (z > y) | |
| 100 z -= L_(1.0); | |
| 101 } | |
| 102 } | |
| 103 return z; | |
| 104 } | |
| 105 | |
| 106 | |
| 107 /* Test for equality. */ | |
| 108 static int | |
| 109 equal (DOUBLE x, DOUBLE y) | |
| 110 { | |
| 111 return (isnand (x) ? isnand (y) : x == y); | |
| 112 } | |
| 113 | |
| 114 /* Test whether the result for a given argument is correct. */ | |
| 115 static bool | |
| 116 correct_result_p (DOUBLE x, DOUBLE result) | |
| 117 { | |
| 118 return | |
| 119 (x < 0 && x >= -1 ? result == - L_(1.0) : | |
| 120 x - 1 < x ? result <= x && result >= x - 1 && x - result < 1 : | |
| 121 equal (result, x)); | |
| 122 } | |
| 123 | |
| 124 /* Test the function for a given argument. */ | |
| 125 static int | |
| 126 check (double x) | |
| 127 { | |
| 128 /* If the reference implementation is incorrect, bail out immediately. */ | |
| 129 double reference = floor_reference (x); | |
| 130 ASSERT (correct_result_p (x, reference)); | |
| 131 /* If the actual implementation is wrong, return an error code. */ | |
| 132 { | |
| 133 double result = floor (x); | |
| 134 if (correct_result_p (x, result)) | |
| 135 return 0; | |
| 136 else | |
| 137 { | |
| 138 #if GNULIB_TEST_FPRINTF_POSIX | |
| 139 fprintf (stderr, "floor %g(%a) = %g(%a) or %g(%a)?\n", | |
| 140 x, x, reference, reference, result, result); | |
| 141 #endif | |
| 142 return 1; | |
| 143 } | |
| 144 } | |
| 145 } | |
| 146 | |
| 147 #define NUM_HIGHBITS 15 | |
| 148 #define NUM_LOWBITS 4 | |
| 149 | |
| 150 int | |
| 151 main () | |
| 152 { | |
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153 #ifdef UINT64_MAX |
| 13974 | 154 unsigned int highbits; |
| 155 unsigned int lowbits; | |
| 156 int error = 0; | |
| 157 for (highbits = 0; highbits < (1 << NUM_HIGHBITS); highbits++) | |
| 158 for (lowbits = 0; lowbits < (1 << NUM_LOWBITS); lowbits++) | |
| 159 { | |
| 160 /* Combine highbits and lowbits into a floating-point number, | |
| 161 sign-extending the lowbits to 64-NUM_HIGHBITS bits. */ | |
| 162 union { double f; uint64_t i; } janus; | |
| 163 janus.i = ((uint64_t) highbits << (64 - NUM_HIGHBITS)) | |
| 164 | ((uint64_t) ((int64_t) ((uint64_t) lowbits << (64 - NUM_LOWBITS)) | |
| 165 >> (64 - NUM_LOWBITS - NUM_HIGHBITS)) | |
| 166 >> NUM_HIGHBITS); | |
| 167 error |= check (janus.f); | |
| 168 } | |
| 169 return (error ? 1 : 0); | |
| 170 #else | |
| 171 fprintf (stderr, "Skipping test: no 64-bit integer type available\n"); | |
| 172 return 77; | |
| 173 #endif | |
| 174 } |