1  /* Round to integer type.  flt-32 version.
       2     Copyright (C) 2016-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <errno.h>
      20  #include <fenv.h>
      21  #include <math.h>
      22  #include <math_private.h>
      23  #include <libm-alias-float.h>
      24  #include <stdbool.h>
      25  #include <stdint.h>
      26  
      27  #define BIAS 0x7f
      28  #define MANT_DIG 24
      29  
      30  #if UNSIGNED
      31  # define RET_TYPE uintmax_t
      32  #else
      33  # define RET_TYPE intmax_t
      34  #endif
      35  
      36  #include <fromfp.h>
      37  
      38  RET_TYPE
      39  FUNC (float x, int round, unsigned int width)
      40  {
      41    if (width > INTMAX_WIDTH)
      42      width = INTMAX_WIDTH;
      43    uint32_t ix;
      44    GET_FLOAT_WORD (ix, x);
      45    bool negative = (ix & 0x80000000) != 0;
      46    if (width == 0)
      47      return fromfp_domain_error (negative, width);
      48    ix &= 0x7fffffff;
      49    if (ix == 0)
      50      return 0;
      51    int exponent = ix >> (MANT_DIG - 1);
      52    exponent -= BIAS;
      53    int max_exponent = fromfp_max_exponent (negative, width);
      54    if (exponent > max_exponent)
      55      return fromfp_domain_error (negative, width);
      56  
      57    ix &= ((1U << (MANT_DIG - 1)) - 1);
      58    ix |= 1U << (MANT_DIG - 1);
      59    uintmax_t uret;
      60    bool half_bit, more_bits;
      61    if (exponent >= MANT_DIG - 1)
      62      {
      63        uret = ix;
      64        uret <<= exponent - (MANT_DIG - 1);
      65        half_bit = false;
      66        more_bits = false;
      67      }
      68    else if (exponent >= -1)
      69      {
      70        uint32_t h = 1U << (MANT_DIG - 2 - exponent);
      71        half_bit = (ix & h) != 0;
      72        more_bits = (ix & (h - 1)) != 0;
      73        uret = ix >> (MANT_DIG - 1 - exponent);
      74      }
      75    else
      76      {
      77        uret = 0;
      78        half_bit = false;
      79        more_bits = true;
      80      }
      81    return fromfp_round_and_return (negative, uret, half_bit, more_bits, round,
      82  				  exponent, max_exponent, width);
      83  }