github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpf/cmp_ui.c (about)

     1  /* mpf_cmp_ui -- Compare a float with an unsigned integer.
     2  
     3  Copyright 1993-1995, 1999, 2001, 2002, 2015 Free Software Foundation, Inc.
     4  
     5  This file is part of the GNU MP Library.
     6  
     7  The GNU MP Library is free software; you can redistribute it and/or modify
     8  it under the terms of either:
     9  
    10    * the GNU Lesser General Public License as published by the Free
    11      Software Foundation; either version 3 of the License, or (at your
    12      option) any later version.
    13  
    14  or
    15  
    16    * the GNU General Public License as published by the Free Software
    17      Foundation; either version 2 of the License, or (at your option) any
    18      later version.
    19  
    20  or both in parallel, as here.
    21  
    22  The GNU MP Library is distributed in the hope that it will be useful, but
    23  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    24  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    25  for more details.
    26  
    27  You should have received copies of the GNU General Public License and the
    28  GNU Lesser General Public License along with the GNU MP Library.  If not,
    29  see https://www.gnu.org/licenses/.  */
    30  
    31  #include "gmp.h"
    32  #include "gmp-impl.h"
    33  
    34  int
    35  mpf_cmp_ui (mpf_srcptr u, unsigned long int vval) __GMP_NOTHROW
    36  {
    37    mp_srcptr up;
    38    mp_size_t usize;
    39    mp_exp_t uexp;
    40    mp_limb_t ulimb;
    41  
    42    usize = SIZ (u);
    43  
    44    /* 1. Is U negative?  */
    45    if (usize < 0)
    46      return -1;
    47    /* We rely on usize being non-negative in the code that follows.  */
    48  
    49    if (vval == 0)
    50      return usize != 0;
    51  
    52    /* 2. Are the exponents different (V's exponent == 1)?  */
    53    uexp = EXP (u);
    54  
    55  #if GMP_NAIL_BITS != 0
    56    if (uexp != 1 + (vval > GMP_NUMB_MAX))
    57      return (uexp < 1 + (vval > GMP_NUMB_MAX)) ? -1 : 1;
    58  #else
    59    if (uexp != 1)
    60      return (uexp < 1) ? -1 : 1;
    61  #endif
    62  
    63    up = PTR (u);
    64  
    65    ASSERT (usize > 0);
    66    ulimb = up[--usize];
    67  #if GMP_NAIL_BITS != 0
    68    if (uexp == 2)
    69      {
    70        if ((ulimb >> GMP_NAIL_BITS) != 0)
    71  	return 1;
    72        ulimb = (ulimb << GMP_NUMB_BITS);
    73        if (usize != 0) ulimb |= up[--usize];
    74      }
    75  #endif
    76  
    77    /* 3. Compare the most significant mantissa limb with V.  */
    78    if (ulimb != vval)
    79      return (ulimb < vval) ? -1 : 1;
    80  
    81    /* Ignore zeroes at the low end of U.  */
    82    for (; *up == 0; ++up)
    83      --usize;
    84  
    85    /* 4. Now, if the number of limbs are different, we have a difference
    86       since we have made sure the trailing limbs are not zero.  */
    87    return (usize > 0);
    88  }