1  /* mpf_cmp_si -- Compare a float with a signed integer.
       2  
       3  Copyright 1993-1995, 1999-2002, 2004, 2012, 2015 Free Software
       4  Foundation, Inc.
       5  
       6  This file is part of the GNU MP Library.
       7  
       8  The GNU MP Library is free software; you can redistribute it and/or modify
       9  it under the terms of either:
      10  
      11    * the GNU Lesser General Public License as published by the Free
      12      Software Foundation; either version 3 of the License, or (at your
      13      option) any later version.
      14  
      15  or
      16  
      17    * the GNU General Public License as published by the Free Software
      18      Foundation; either version 2 of the License, or (at your option) any
      19      later version.
      20  
      21  or both in parallel, as here.
      22  
      23  The GNU MP Library is distributed in the hope that it will be useful, but
      24  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
      25  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      26  for more details.
      27  
      28  You should have received copies of the GNU General Public License and the
      29  GNU Lesser General Public License along with the GNU MP Library.  If not,
      30  see https://www.gnu.org/licenses/.  */
      31  
      32  #include "gmp-impl.h"
      33  
      34  int
      35  mpf_cmp_si (mpf_srcptr u, 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    int usign;
      42    unsigned long abs_vval;
      43  
      44    usize = SIZ (u);
      45  
      46    /* 1. Are the signs different?  */
      47    if ((usize < 0) == (vval < 0)) /* don't use xor, type size may differ */
      48      {
      49        /* U and V are both non-negative or both negative.  */
      50        if (usize == 0)
      51  	/* vval >= 0 */
      52  	return -(vval != 0);
      53        if (vval == 0)
      54  	/* usize >= 0 */
      55  	return usize != 0;
      56        /* Fall out.  */
      57      }
      58    else
      59      {
      60        /* Either U or V is negative, but not both.  */
      61        return usize >= 0 ? 1 : -1;
      62      }
      63  
      64    /* U and V have the same sign and are both non-zero.  */
      65  
      66    /* 2. Are the exponents different (V's exponent == 1)?  */
      67    uexp = EXP (u);
      68    usign = usize >= 0 ? 1 : -1;
      69    usize = ABS (usize);
      70    abs_vval = ABS_CAST (unsigned long, vval);
      71  
      72  #if GMP_NAIL_BITS != 0
      73    if (uexp != 1 + (abs_vval > GMP_NUMB_MAX))
      74      return (uexp < 1 + (abs_vval > GMP_NUMB_MAX)) ? -usign : usign;
      75  #else
      76    if (uexp != 1)
      77      return (uexp < 1) ? -usign : usign;
      78  #endif
      79  
      80    up = PTR (u);
      81  
      82    ASSERT (usize > 0);
      83    ulimb = up[--usize];
      84  #if GMP_NAIL_BITS != 0
      85    if (uexp == 2)
      86      {
      87        if ((ulimb >> GMP_NAIL_BITS) != 0)
      88  	return usign;
      89        ulimb = (ulimb << GMP_NUMB_BITS);
      90        if (usize != 0) ulimb |= up[--usize];
      91      }
      92  #endif
      93  
      94    /* 3. Compare the most significant mantissa limb with V.  */
      95    if (ulimb != abs_vval)
      96      return (ulimb < abs_vval) ? -usign : usign;
      97  
      98    /* Ignore zeroes at the low end of U.  */
      99    for (; *up == 0; ++up)
     100      --usize;
     101  
     102    /* 4. Now, if the number of limbs are different, we have a difference
     103       since we have made sure the trailing limbs are not zero.  */
     104    if (usize > 0)
     105      return usign;
     106  
     107    /* Wow, we got zero even if we tried hard to avoid it.  */
     108    return 0;
     109  }