1  /* Round argument to nearest integral value according to current rounding
       2     direction.
       3     Copyright (C) 1997-2023 Free Software Foundation, Inc.
       4     This file is part of the GNU C Library.
       5  
       6     The GNU C Library is free software; you can redistribute it and/or
       7     modify it under the terms of the GNU Lesser General Public
       8     License as published by the Free Software Foundation; either
       9     version 2.1 of the License, or (at your option) any later version.
      10  
      11     The GNU C Library is distributed in the hope that it will be useful,
      12     but WITHOUT ANY WARRANTY; without even the implied warranty of
      13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14     Lesser General Public License for more details.
      15  
      16     You should have received a copy of the GNU Lesser General Public
      17     License along with the GNU C Library; if not, see
      18     <https://www.gnu.org/licenses/>.  */
      19  
      20  #include <fenv.h>
      21  #include <limits.h>
      22  #include <math.h>
      23  
      24  #include <math-narrow-eval.h>
      25  #include <math_private.h>
      26  #include <libm-alias-float.h>
      27  #include <fix-fp-int-convert-overflow.h>
      28  #include <math-use-builtins.h>
      29  
      30  
      31  long int
      32  __lrintf (float x)
      33  {
      34  #if USE_LRINTF_BUILTIN
      35    return __builtin_lrintf (x);
      36  #else
      37    /* Use generic implementation.  */
      38    static const float two23[2] =
      39    {
      40      8.3886080000e+06, /* 0x4B000000 */
      41     -8.3886080000e+06, /* 0xCB000000 */
      42    };
      43  
      44    int32_t j0;
      45    uint32_t i0;
      46    float w;
      47    float t;
      48    long int result;
      49    int sx;
      50  
      51    GET_FLOAT_WORD (i0, x);
      52  
      53    sx = i0 >> 31;
      54    j0 = ((i0 >> 23) & 0xff) - 0x7f;
      55    i0 &= 0x7fffff;
      56    i0 |= 0x800000;
      57  
      58    if (j0 < (int32_t) (sizeof (long int) * 8) - 1)
      59      {
      60        if (j0 >= 23)
      61  	result = (long int) i0 << (j0 - 23);
      62        else
      63  	{
      64  	  w = math_narrow_eval (two23[sx] + x);
      65  	  t = w - two23[sx];
      66  	  GET_FLOAT_WORD (i0, t);
      67  	  j0 = ((i0 >> 23) & 0xff) - 0x7f;
      68  	  i0 &= 0x7fffff;
      69  	  i0 |= 0x800000;
      70  
      71  	  result = (j0 < 0 ? 0 : i0 >> (23 - j0));
      72  	}
      73      }
      74    else
      75      {
      76  #ifdef FE_INVALID
      77        /* The number is too large.  Unless it rounds to LONG_MIN,
      78  	 FE_INVALID must be raised and the return value is
      79  	 unspecified.  */
      80        if (FIX_FLT_LONG_CONVERT_OVERFLOW && x != (float) LONG_MIN)
      81  	{
      82  	  feraiseexcept (FE_INVALID);
      83  	  return sx == 0 ? LONG_MAX : LONG_MIN;
      84  	}
      85  #endif
      86        return (long int) x;
      87      }
      88  
      89    return sx ? -result : result;
      90  #endif /* ! USE_LRINTF_BUILTIN  */
      91  }
      92  
      93  libm_alias_float (__lrint, lrint)