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92 lines
2.5 KiB
C
92 lines
2.5 KiB
C
/* Round to integer type. ldbl-128 version.
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Copyright (C) 2016-2023 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <fenv.h>
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#include <math.h>
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#include <math_private.h>
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#include <libm-alias-ldouble.h>
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#include <stdbool.h>
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#include <stdint.h>
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#define BIAS 0x3fff
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#define MANT_DIG 113
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#if UNSIGNED
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# define RET_TYPE uintmax_t
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#else
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# define RET_TYPE intmax_t
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#endif
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#include <fromfp.h>
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RET_TYPE
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FUNC (_Float128 x, int round, unsigned int width)
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{
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if (width > INTMAX_WIDTH)
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width = INTMAX_WIDTH;
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uint64_t hx, lx;
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GET_LDOUBLE_WORDS64 (hx, lx, x);
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bool negative = (hx & 0x8000000000000000ULL) != 0;
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if (width == 0)
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return fromfp_domain_error (negative, width);
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hx &= 0x7fffffffffffffffULL;
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if ((hx | lx) == 0)
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return 0;
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int exponent = hx >> (MANT_DIG - 1 - 64);
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exponent -= BIAS;
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int max_exponent = fromfp_max_exponent (negative, width);
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if (exponent > max_exponent)
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return fromfp_domain_error (negative, width);
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hx &= ((1ULL << (MANT_DIG - 1 - 64)) - 1);
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hx |= 1ULL << (MANT_DIG - 1 - 64);
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uintmax_t uret;
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bool half_bit, more_bits;
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/* The exponent is at most 63, so we are shifting right by at least
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49 bits. */
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if (exponent >= -1)
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{
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int shift = MANT_DIG - 1 - exponent;
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if (shift <= 64)
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{
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uint64_t h = 1ULL << (shift - 1);
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half_bit = (lx & h) != 0;
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more_bits = (lx & (h - 1)) != 0;
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uret = hx << (64 - shift);
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if (shift != 64)
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uret |= lx >> shift;
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}
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else
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{
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uint64_t h = 1ULL << (shift - 1 - 64);
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half_bit = (hx & h) != 0;
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more_bits = ((hx & (h - 1)) | lx) != 0;
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uret = hx >> (shift - 64);
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}
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}
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else
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{
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uret = 0;
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half_bit = false;
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more_bits = true;
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}
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return fromfp_round_and_return (negative, uret, half_bit, more_bits, round,
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exponent, max_exponent, width);
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}
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