diff options
Diffstat (limited to 'sysdeps/ieee754/dbl-64/s_fromfp_main.c')
-rw-r--r-- | sysdeps/ieee754/dbl-64/s_fromfp_main.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/sysdeps/ieee754/dbl-64/s_fromfp_main.c b/sysdeps/ieee754/dbl-64/s_fromfp_main.c new file mode 100644 index 0000000000..c0cd271ad5 --- /dev/null +++ b/sysdeps/ieee754/dbl-64/s_fromfp_main.c @@ -0,0 +1,82 @@ +/* Round to integer type. dbl-64 version. + Copyright (C) 2016 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + 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 + <http://www.gnu.org/licenses/>. */ + +#include <errno.h> +#include <fenv.h> +#include <math.h> +#include <math_private.h> +#include <stdbool.h> +#include <stdint.h> + +#define BIAS 0x3ff +#define MANT_DIG 53 + +#if UNSIGNED +# define RET_TYPE uintmax_t +#else +# define RET_TYPE intmax_t +#endif + +#include <fromfp.h> + +RET_TYPE +FUNC (double x, int round, unsigned int width) +{ + if (width > INTMAX_WIDTH) + width = INTMAX_WIDTH; + uint64_t ix; + EXTRACT_WORDS64 (ix, x); + bool negative = (ix & 0x8000000000000000ULL) != 0; + if (width == 0) + return fromfp_domain_error (negative, width); + ix &= 0x7fffffffffffffffULL; + if (ix == 0) + return 0; + int exponent = ix >> (MANT_DIG - 1); + exponent -= BIAS; + int max_exponent = fromfp_max_exponent (negative, width); + if (exponent > max_exponent) + return fromfp_domain_error (negative, width); + + ix &= ((1ULL << (MANT_DIG - 1)) - 1); + ix |= 1ULL << (MANT_DIG - 1); + uintmax_t uret; + bool half_bit, more_bits; + if (exponent >= MANT_DIG - 1) + { + uret = ix; + uret <<= exponent - (MANT_DIG - 1); + half_bit = false; + more_bits = false; + } + else if (exponent >= -1) + { + uint64_t h = 1ULL << (MANT_DIG - 2 - exponent); + half_bit = (ix & h) != 0; + more_bits = (ix & (h - 1)) != 0; + uret = ix >> (MANT_DIG - 1 - exponent); + } + else + { + uret = 0; + half_bit = false; + more_bits = true; + } + return fromfp_round_and_return (negative, uret, half_bit, more_bits, round, + exponent, max_exponent, width); +} |