diff options
Diffstat (limited to 'sysdeps/ieee754/dbl-64/s_modf.c')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/s_modf.c | 109 |
1 files changed, 57 insertions, 52 deletions
diff --git a/sysdeps/ieee754/dbl-64/s_modf.c b/sysdeps/ieee754/dbl-64/s_modf.c index 0de2084..90cd8e8 100644 --- a/sysdeps/ieee754/dbl-64/s_modf.c +++ b/sysdeps/ieee754/dbl-64/s_modf.c @@ -1,63 +1,68 @@ -/* - * ==================================================== - * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. - * - * Developed at SunPro, a Sun Microsystems, Inc. business. - * Permission to use, copy, modify, and distribute this - * software is freely granted, provided that this notice - * is preserved. - * ==================================================== - */ +/* Extract signed integral and fractional values. + Copyright (C) 1993-2025 Free Software Foundation, Inc. + This file is part of the GNU C Library. -/* - * modf(double x, double *iptr) - * return fraction part of x, and return x's integral part in *iptr. - * Method: - * Bit twiddling. - * - * Exception: - * No exception. - */ + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ #include <math.h> -#include <math_private.h> #include <libm-alias-double.h> -#include <stdint.h> - -static const double one = 1.0; +#include "math_config.h" +#include <math-use-builtins-trunc.h> double -__modf(double x, double *iptr) +__modf (double x, double *iptr) { - int64_t i0; - int32_t j0; - EXTRACT_WORDS64(i0,x); - j0 = ((i0>>52)&0x7ff)-0x3ff; /* exponent of x */ - if(j0<52) { /* integer part in x */ - if(j0<0) { /* |x|<1 */ - /* *iptr = +-0 */ - INSERT_WORDS64(*iptr,i0&UINT64_C(0x8000000000000000)); - return x; - } else { - uint64_t i = UINT64_C(0x000fffffffffffff)>>j0; - if((i0&i)==0) { /* x is integral */ - *iptr = x; - /* return +-0 */ - INSERT_WORDS64(x,i0&UINT64_C(0x8000000000000000)); - return x; - } else { - INSERT_WORDS64(*iptr,i0&(~i)); - return x - *iptr; - } - } - } else { /* no fraction part */ - *iptr = x*one; - /* We must handle NaNs separately. */ - if (j0 == 0x400 && (i0 & UINT64_C(0xfffffffffffff))) - return x*one; - INSERT_WORDS64(x,i0&UINT64_C(0x8000000000000000)); /* return +-0 */ - return x; + uint64_t t = asuint64 (x); +#if USE_TRUNC_BUILTIN + if (is_inf (t)) + { + *iptr = x; + return copysign (0.0, x); + } + *iptr = trunc (x); + return copysign (x - *iptr, x); +#else + int e = get_exponent (t); + /* No fraction part. */ + if (e < MANTISSA_WIDTH) + { + if (e < 0) + { + /* |x|<1 -> *iptr = +-0 */ + *iptr = asdouble (t & SIGN_MASK); + return x; + } + + uint64_t i = MANTISSA_MASK >> e; + if ((t & i) == 0) + { + /* x in integral, return +-0 */ + *iptr = x; + return asdouble (t & SIGN_MASK); } + + *iptr = asdouble (t & ~i); + return x - *iptr; + } + + /* Set invalid operation for sNaN. */ + *iptr = x * 1.0; + if ((e == 0x400) && (t & MANTISSA_MASK)) + return *iptr; + return asdouble (t & SIGN_MASK); +#endif } #ifndef __modf libm_alias_double (__modf, modf) |