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