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Diffstat (limited to 'tests/test-frexp.c')
| -rw-r--r-- | tests/test-frexp.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/tests/test-frexp.c b/tests/test-frexp.c new file mode 100644 index 00000000..4ed24d29 --- /dev/null +++ b/tests/test-frexp.c @@ -0,0 +1,196 @@ +/* Test of splitting a double into fraction and mantissa. + Copyright (C) 2007-2011 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ + +/* Written by Bruno Haible <bruno@clisp.org>, 2007. */ + +#include <config.h> + +#include <math.h> + +#include "signature.h" +SIGNATURE_CHECK (frexp, double, (double, int *)); + +#include <float.h> + +#include "isnand-nolibm.h" +#include "minus-zero.h" +#include "nan.h" +#include "macros.h" + +/* Avoid some warnings from "gcc -Wshadow". + This file doesn't use the exp() function. */ +#undef exp +#define exp exponent + +static double +my_ldexp (double x, int d) +{ + for (; d > 0; d--) + x *= 2.0; + for (; d < 0; d++) + x *= 0.5; + return x; +} + +int +main () +{ + int i; + /* The use of 'volatile' guarantees that excess precision bits are dropped + when dealing with denormalized numbers. It is necessary on x86 systems + where double-floats are not IEEE compliant by default, to avoid that the + results become platform and compiler option dependent. 'volatile' is a + portable alternative to gcc's -ffloat-store option. */ + volatile double x; + + { /* NaN. */ + int exp = -9999; + double mantissa; + x = NaNd (); + mantissa = frexp (x, &exp); + ASSERT (isnand (mantissa)); + } + + { /* Positive infinity. */ + int exp = -9999; + double mantissa; + x = 1.0 / 0.0; + mantissa = frexp (x, &exp); + ASSERT (mantissa == x); + } + + { /* Negative infinity. */ + int exp = -9999; + double mantissa; + x = -1.0 / 0.0; + mantissa = frexp (x, &exp); + ASSERT (mantissa == x); + } + + { /* Positive zero. */ + int exp = -9999; + double mantissa; + x = 0.0; + mantissa = frexp (x, &exp); + ASSERT (exp == 0); + ASSERT (mantissa == x); + ASSERT (!signbit (mantissa)); + } + + { /* Negative zero. */ + int exp = -9999; + double mantissa; + x = minus_zerod; + mantissa = frexp (x, &exp); + ASSERT (exp == 0); + ASSERT (mantissa == x); + ASSERT (signbit (mantissa)); + } + + for (i = 1, x = 1.0; i <= DBL_MAX_EXP; i++, x *= 2.0) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa == 0.5); + } + for (i = 1, x = 1.0; i >= DBL_MIN_EXP; i--, x *= 0.5) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa == 0.5); + } + for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa == 0.5); + } + + for (i = 1, x = -1.0; i <= DBL_MAX_EXP; i++, x *= 2.0) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa == -0.5); + } + for (i = 1, x = -1.0; i >= DBL_MIN_EXP; i--, x *= 0.5) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa == -0.5); + } + for (; i >= DBL_MIN_EXP - 100 && x < 0.0; i--, x *= 0.5) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa == -0.5); + } + + for (i = 1, x = 1.01; i <= DBL_MAX_EXP; i++, x *= 2.0) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa == 0.505); + } + for (i = 1, x = 1.01; i >= DBL_MIN_EXP; i--, x *= 0.5) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa == 0.505); + } + for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa >= 0.5); + ASSERT (mantissa < 1.0); + ASSERT (mantissa == my_ldexp (x, - exp)); + } + + for (i = 1, x = 1.73205; i <= DBL_MAX_EXP; i++, x *= 2.0) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa == 0.866025); + } + for (i = 1, x = 1.73205; i >= DBL_MIN_EXP; i--, x *= 0.5) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i); + ASSERT (mantissa == 0.866025); + } + for (; i >= DBL_MIN_EXP - 100 && x > 0.0; i--, x *= 0.5) + { + int exp = -9999; + double mantissa = frexp (x, &exp); + ASSERT (exp == i || exp == i + 1); + ASSERT (mantissa >= 0.5); + ASSERT (mantissa < 1.0); + ASSERT (mantissa == my_ldexp (x, - exp)); + } + + return 0; +} |