diff options
Diffstat (limited to 'sysdeps/ieee754/ldbl-128ibm/s_fromfpl_main.c')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/s_fromfpl_main.c | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_fromfpl_main.c b/sysdeps/ieee754/ldbl-128ibm/s_fromfpl_main.c new file mode 100644 index 0000000000..76287c33dc --- /dev/null +++ b/sysdeps/ieee754/ldbl-128ibm/s_fromfpl_main.c @@ -0,0 +1,147 @@ +/* Round to integer type. ldbl-128ibm version. + Copyright (C) 2016-2018 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 (long double x, int round, unsigned int width) +{ + double hi, lo; + if (width > INTMAX_WIDTH) + width = INTMAX_WIDTH; + uint64_t hx, lx; + ldbl_unpack (x, &hi, &lo); + EXTRACT_WORDS64 (hx, hi); + EXTRACT_WORDS64 (lx, lo); + bool negative = (hx & 0x8000000000000000ULL) != 0; + bool lo_negative = (lx & 0x8000000000000000ULL) != 0; + if (width == 0) + return fromfp_domain_error (negative, width); + hx &= 0x7fffffffffffffffULL; + lx &= 0x7fffffffffffffffULL; + if ((hx | lx) == 0) + return 0; + int hi_exponent = hx >> (MANT_DIG - 1); + hi_exponent -= BIAS; + int exponent = hi_exponent; + hx &= ((1ULL << (MANT_DIG - 1)) - 1); + if (hx == 0 && lx != 0 && lo_negative != negative) + exponent--; + int max_exponent = fromfp_max_exponent (negative, width); + if (exponent > max_exponent) + return fromfp_domain_error (negative, width); + int lo_exponent = lx >> (MANT_DIG - 1); + lo_exponent -= BIAS; + + /* Convert the high part to integer. */ + hx |= 1ULL << (MANT_DIG - 1); + uintmax_t uret; + bool half_bit, more_bits; + if (hi_exponent >= MANT_DIG - 1) + { + uret = hx; + uret <<= hi_exponent - (MANT_DIG - 1); + half_bit = false; + more_bits = false; + } + else if (hi_exponent >= -1) + { + uint64_t h = 1ULL << (MANT_DIG - 2 - hi_exponent); + half_bit = (hx & h) != 0; + more_bits = (hx & (h - 1)) != 0; + uret = hx >> (MANT_DIG - 1 - hi_exponent); + } + else + { + uret = 0; + half_bit = false; + more_bits = true; + } + + /* Likewise, the low part. */ + if (lx != 0) + { + uintmax_t lo_uret; + bool lo_half_bit, lo_more_bits; + lx &= ((1ULL << (MANT_DIG - 1)) - 1); + lx |= 1ULL << (MANT_DIG - 1); + /* The high part exponent is at most 64, so the low part + exponent is at most 11. */ + if (lo_exponent >= -1) + { + uint64_t h = 1ULL << (MANT_DIG - 2 - lo_exponent); + lo_half_bit = (lx & h) != 0; + lo_more_bits = (lx & (h - 1)) != 0; + lo_uret = lx >> (MANT_DIG - 1 - lo_exponent); + } + else + { + lo_uret = 0; + lo_half_bit = false; + lo_more_bits = true; + } + if (lo_negative == negative) + { + uret += lo_uret; + half_bit |= lo_half_bit; + more_bits |= lo_more_bits; + } + else + { + uret -= lo_uret; + if (lo_half_bit) + { + uret--; + half_bit = true; + } + if (lo_more_bits && !more_bits) + { + if (half_bit) + { + half_bit = false; + more_bits = true; + } + else + { + uret--; + half_bit = true; + more_bits = true; + } + } + } + } + + return fromfp_round_and_return (negative, uret, half_bit, more_bits, round, + exponent, max_exponent, width); +} |