source/libs/gmp/gmp-src/mpz/cmp_d.c

   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 }