1  /* Round a double value to a long long in the current rounding mode.
       2     Copyright (C) 1997-2023 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 <limits.h>
      20  #include <math.h>
      21  #include <math_ldbl_opt.h>
      22  #include <math_private.h>
      23  #include <stdint.h>
      24  #include <libm-alias-double.h>
      25  
      26  long long int
      27  __llrint (double x)
      28  {
      29  #ifdef _ARCH_PWR4
      30    /* Assume powerpc64 instructions availability.  */
      31    long long int ret;
      32    __asm__ ("fctid %0, %1" : "=d" (ret) : "d" (x));
      33    return ret;
      34  #else
      35    double rx = rint (x);
      36    if (HAVE_PPC_FCTIDZ || rx != x)
      37      return (long long int) rx;
      38    else
      39      {
      40        /* Avoid incorrect exceptions from libgcc conversions (as of GCC
      41  	 5): <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59412>.  */
      42        if (fabs (rx) < 0x1p31)
      43  	return (long long int) (long int) rx;
      44        uint64_t i0;
      45        EXTRACT_WORDS64 (i0, rx);
      46        int exponent = ((i0 >> 52) & 0x7ff) - 0x3ff;
      47        if (exponent < 63)
      48  	{
      49  	  unsigned long long int mant
      50  	    = (i0 & ((1ULL << 52) - 1)) | (1ULL << 52);
      51  	  if (exponent < 52)
      52  	    mant >>= 52 - exponent;
      53  	  else
      54  	    mant <<= exponent - 52;
      55  	  return (long long int) ((i0 & (1ULL << 63)) != 0 ? -mant : mant);
      56  	}
      57        else if (rx == (double) LLONG_MIN)
      58  	return LLONG_MIN;
      59        else
      60  	return (long long int) (long int) rx << 32;
      61      }
      62  #endif
      63  }
      64  #ifndef __llrint
      65  libm_alias_double (__llrint, llrint)
      66  #endif