Blame sysdeps/ieee754/flt-32/s_fromfpf_main.c

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/* Round to integer type.  flt-32 version.
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   Copyright (C) 2016-2018 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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   <http://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-float.h>
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#include <stdbool.h>
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#include <stdint.h>
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#define BIAS 0x7f
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#define MANT_DIG 24
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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 (float 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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  uint32_t ix;
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  GET_FLOAT_WORD (ix, x);
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  bool negative = (ix & 0x80000000) != 0;
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  if (width == 0)
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    return fromfp_domain_error (negative, width);
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  ix &= 0x7fffffff;
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  if (ix == 0)
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    return 0;
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  int exponent = ix >> (MANT_DIG - 1);
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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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  ix &= ((1U << (MANT_DIG - 1)) - 1);
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  ix |= 1U << (MANT_DIG - 1);
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  uintmax_t uret;
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  bool half_bit, more_bits;
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  if (exponent >= MANT_DIG - 1)
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    {
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      uret = ix;
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      uret <<= exponent - (MANT_DIG - 1);
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      half_bit = false;
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      more_bits = false;
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    }
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  else if (exponent >= -1)
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    {
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      uint32_t h = 1U << (MANT_DIG - 2 - exponent);
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      half_bit = (ix & h) != 0;
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      more_bits = (ix & (h - 1)) != 0;
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      uret = ix >> (MANT_DIG - 1 - exponent);
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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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}