Mercurial > gnulib
view lib/signbitf.c @ 40214:452ab00796c7
Fix undefined behaviour.
* lib/bitrotate.h (rotl16, rotr16, rotl8, rotr8): Case x to
'unsigned int', to avoid shift operations on 'int'.
* lib/xmemdup0.c (xmemdup0): Don't invoke memcpy with a zero size.
* tests/test-count-leading-zeros.c (main): Use a random number that has
as many bits as TYPE, not only 2*15 or 2*31 bits.
* tests/test-count-trailing-zeros.c (main): Likewise.
* tests/test-count-one-bits.c (main): Likewise.
* tests/test-memmem.c: Don't include "null-ptr.h".
(main): Use zerosize_ptr() instead of null_ptr().
* modules/memmem-tests (Files): Remove tests/null-ptr.h.
author | Bruno Haible <bruno@clisp.org> |
---|---|
date | Sat, 09 Mar 2019 20:32:25 +0100 |
parents | b06060465f09 |
children |
line wrap: on
line source
/* signbit() macro: Determine the sign bit of a floating-point number. Copyright (C) 2007, 2009-2019 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 <https://www.gnu.org/licenses/>. */ #include <config.h> /* Specification. */ #include <math.h> #include <string.h> #include "isnanf-nolibm.h" #include "float+.h" #ifdef gl_signbitf_OPTIMIZED_MACRO # undef gl_signbitf #endif int gl_signbitf (float arg) { #if defined FLT_SIGNBIT_WORD && defined FLT_SIGNBIT_BIT /* The use of a union to extract the bits of the representation of a 'long double' is safe in practice, despite of the "aliasing rules" of C99, because the GCC docs say "Even with '-fstrict-aliasing', type-punning is allowed, provided the memory is accessed through the union type." and similarly for other compilers. */ # define NWORDS \ ((sizeof (float) + sizeof (unsigned int) - 1) / sizeof (unsigned int)) union { float value; unsigned int word[NWORDS]; } m; m.value = arg; return (m.word[FLT_SIGNBIT_WORD] >> FLT_SIGNBIT_BIT) & 1; #elif HAVE_COPYSIGNF_IN_LIBC return copysignf (1.0f, arg) < 0; #else /* This does not do the right thing for NaN, but this is irrelevant for most use cases. */ if (isnanf (arg)) return 0; if (arg < 0.0f) return 1; else if (arg == 0.0f) { /* Distinguish 0.0f and -0.0f. */ static float plus_zero = 0.0f; float arg_mem = arg; return (memcmp (&plus_zero, &arg_mem, SIZEOF_FLT) != 0); } else return 0; #endif }