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

     1  /* mpz_cmp_d -- compare absolute values of mpz and double.
     2  
     3  Copyright 2001-2003 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 "config.h"
    32  
    33  #if HAVE_FLOAT_H
    34  #include <float.h>  /* for DBL_MAX */
    35  #endif
    36  
    37  #include "gmp.h"
    38  #include "gmp-impl.h"
    39  
    40  
    41  #define RETURN_CMP(zl, dl)                      \
    42    do {                                          \
    43      zlimb = (zl);                               \
    44      dlimb = (dl);                               \
    45      if (zlimb != dlimb)                         \
    46        return (zlimb >= dlimb ? ret : -ret);     \
    47    } while (0)
    48  
    49  #define RETURN_NONZERO(ptr, size, val)          \
    50    do {                                          \
    51      mp_size_t __i;                              \
    52      for (__i = (size)-1; __i >= 0; __i--)       \
    53        if ((ptr)[__i] != 0)                      \
    54          return val;                             \
    55      return 0;                                   \
    56    } while (0)
    57  
    58  
    59  int
    60  mpz_cmp_d (mpz_srcptr z, double d)
    61  {
    62    mp_limb_t  darray[LIMBS_PER_DOUBLE], zlimb, dlimb;
    63    mp_srcptr  zp;
    64    mp_size_t  zsize;
    65    int        dexp, ret;
    66  
    67    /* d=NaN is an invalid operation, there's no sensible return value.
    68       d=Inf or -Inf is always bigger than z.  */
    69    DOUBLE_NAN_INF_ACTION (d, __gmp_invalid_operation (), goto z_zero);
    70  
    71    /* 1. Either operand zero. */
    72    zsize = SIZ(z);
    73    if (d == 0.0)
    74      return zsize;
    75    if (zsize == 0)
    76      {
    77      z_zero:
    78        return (d < 0.0 ? 1 : -1);
    79      }
    80  
    81    /* 2. Opposite signs. */
    82    if (zsize >= 0)
    83      {
    84        if (d < 0.0)
    85  	return 1;    /* >=0 cmp <0 */
    86        ret = 1;
    87      }
    88    else
    89      {
    90        if (d >= 0.0)
    91  	return -1;   /* <0 cmp >=0 */
    92        ret = -1;
    93        d = -d;
    94        zsize = -zsize;
    95      }
    96  
    97    /* 3. Small d, knowing abs(z) >= 1. */
    98    if (d < 1.0)
    99      return ret;
   100  
   101    dexp = __gmp_extract_double (darray, d);
   102    ASSERT (dexp >= 1);
   103  
   104    /* 4. Check for different high limb positions. */
   105    if (zsize != dexp)
   106      return (zsize >= dexp ? ret : -ret);
   107  
   108    /* 5. Limb data. */
   109    zp = PTR(z);
   110  
   111  #if LIMBS_PER_DOUBLE == 2
   112    RETURN_CMP (zp[zsize-1], darray[1]);
   113    if (zsize == 1)
   114      return (darray[0] != 0 ? -ret : 0);
   115  
   116    RETURN_CMP (zp[zsize-2], darray[0]);
   117    RETURN_NONZERO (zp, zsize-2, ret);
   118  #endif
   119  
   120  #if LIMBS_PER_DOUBLE == 3
   121    RETURN_CMP (zp[zsize-1], darray[2]);
   122    if (zsize == 1)
   123      return ((darray[0] | darray[1]) != 0 ? -ret : 0);
   124  
   125    RETURN_CMP (zp[zsize-2], darray[1]);
   126    if (zsize == 2)
   127      return (darray[0] != 0 ? -ret : 0);
   128  
   129    RETURN_CMP (zp[zsize-3], darray[0]);
   130    RETURN_NONZERO (zp, zsize-3, ret);
   131  #endif
   132  
   133  #if LIMBS_PER_DOUBLE >= 4
   134    {
   135      int i;
   136      for (i = 1; i <= LIMBS_PER_DOUBLE; i++)
   137        {
   138  	RETURN_CMP (zp[zsize-i], darray[LIMBS_PER_DOUBLE-i]);
   139  	if (i >= zsize)
   140  	  RETURN_NONZERO (darray, LIMBS_PER_DOUBLE-i, -ret);
   141        }
   142      RETURN_NONZERO (zp, zsize-LIMBS_PER_DOUBLE, ret);
   143    }
   144  #endif
   145  }