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

   1 /* mpz_cmpabs_d -- compare absolute values of mpz and double.
   2
   3 Copyright 2001-2003, 2012 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 ? 1 : -1); \
  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_cmpabs_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;
  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 (), return -1);
  70
  71   /* 1. Check for either operand zero. */
  72   zsize = SIZ(z);
  73   if (d == 0.0)
  74     return (zsize != 0);
  75   if (zsize == 0)
  76     return -1; /* d != 0 */
  77
  78   /* 2. Ignore signs. */
  79   zsize = ABS(zsize);
  80   d = ABS(d);
  81
  82   /* 3. Small d, knowing abs(z) >= 1. */
  83   if (d < 1.0)
  84     return 1;
  85
  86   dexp = __gmp_extract_double (darray, d);
  87   ASSERT (dexp >= 1);
  88
  89   /* 4. Check for different high limb positions. */
  90   if (zsize != dexp)
  91     return (zsize >= dexp ? 1 : -1);
  92
  93   /* 5. Limb data. */
  94   zp = PTR(z);
  95
  96 #if LIMBS_PER_DOUBLE == 2
  97   RETURN_CMP (zp[zsize-1], darray[1]);
  98   if (zsize == 1)
  99     return (darray[0] != 0 ? -1 : 0);
 100
 101   RETURN_CMP (zp[zsize-2], darray[0]);
 102   RETURN_NONZERO (zp, zsize-2, 1);
 103 #endif
 104
 105 #if LIMBS_PER_DOUBLE == 3
 106   RETURN_CMP (zp[zsize-1], darray[2]);
 107   if (zsize == 1)
 108     return ((darray[0] | darray[1]) != 0 ? -1 : 0);
 109
 110   RETURN_CMP (zp[zsize-2], darray[1]);
 111   if (zsize == 2)
 112     return (darray[0] != 0 ? -1 : 0);
 113
 114   RETURN_CMP (zp[zsize-3], darray[0]);
 115   RETURN_NONZERO (zp, zsize-3, 1);
 116 #endif
 117
 118 #if LIMBS_PER_DOUBLE >= 4
 119   {
 120     int i;
 121     for (i = 1; i <= LIMBS_PER_DOUBLE; i++)
 122       {
 123         RETURN_CMP (zp[zsize-i], darray[LIMBS_PER_DOUBLE-i]);
 124         if (i >= zsize)
 125           RETURN_NONZERO (darray, LIMBS_PER_DOUBLE-i, -1);
 126       }
 127     RETURN_NONZERO (zp, zsize-LIMBS_PER_DOUBLE, 1);
 128   }
 129 #endif
 130 }