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

     1  /* mpq_cmp(u,v) -- Compare U, V.  Return positive, zero, or negative
     2     based on if U > V, U == V, or U < V.
     3  
     4  Copyright 1991, 1994, 1996, 2001, 2002, 2005, 2015 Free Software 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.h"
    33  #include "gmp-impl.h"
    34  #include "longlong.h"
    35  
    36  static int
    37  mpq_cmp_numden (mpq_srcptr op1, mpz_srcptr num_op2, mpz_srcptr den_op2)
    38  {
    39    mp_size_t num1_size = SIZ(NUM(op1));
    40    mp_size_t den1_size = SIZ(DEN(op1));
    41    mp_size_t num2_size = SIZ(num_op2);
    42    mp_size_t den2_size = SIZ(den_op2);
    43    int op2_is_int;
    44    mp_limb_t d1h, d2h;
    45    mp_size_t tmp1_size, tmp2_size;
    46    mp_ptr tmp1_ptr, tmp2_ptr;
    47    mp_size_t num1_sign;
    48    int cc;
    49    TMP_DECL;
    50  
    51    /* need canonical signs to get right result */
    52    ASSERT (den1_size > 0);
    53    ASSERT (den2_size > 0);
    54  
    55    if (num1_size == 0)
    56      return -num2_size;
    57    if (num2_size == 0)
    58      return num1_size;
    59    if ((num1_size ^ num2_size) < 0) /* I.e. are the signs different? */
    60      return num1_size;
    61  
    62    num1_sign = num1_size;
    63    num1_size = ABS (num1_size);
    64  
    65    /* THINK: Does storing d1h and d2h make sense? */
    66    d1h = PTR(DEN(op1))[den1_size - 1];
    67    d2h = PTR(den_op2)[den2_size - 1];
    68    op2_is_int = (den2_size | d2h) == 1;
    69    if (op2_is_int == (den1_size | d1h)) /* Both ops are integers */
    70      /* return mpz_cmp (NUM (op1), num_op2); */
    71      {
    72        int cmp;
    73  
    74        if (num1_sign != num2_size)
    75  	return num1_sign - num2_size;
    76  
    77        cmp = mpn_cmp (PTR(NUM(op1)), PTR(num_op2), num1_size);
    78        return (num1_sign > 0 ? cmp : -cmp);
    79      }
    80  
    81    num2_size = ABS (num2_size);
    82  
    83    tmp1_size = num1_size + den2_size;
    84    tmp2_size = num2_size + den1_size;
    85  
    86    /* 1. Check to see if we can tell which operand is larger by just looking at
    87       the number of limbs.  */
    88  
    89    /* NUM1 x DEN2 is either TMP1_SIZE limbs or TMP1_SIZE-1 limbs.
    90       Same for NUM1 x DEN1 with respect to TMP2_SIZE.  */
    91    if (tmp1_size > tmp2_size + 1)
    92      /* NUM1 x DEN2 is surely larger in magnitude than NUM2 x DEN1.  */
    93      return num1_sign;
    94    if (tmp2_size + op2_is_int > tmp1_size + 1)
    95      /* NUM1 x DEN2 is surely smaller in magnitude than NUM2 x DEN1.  */
    96      return -num1_sign;
    97  
    98    /* 2. Same, but compare the number of significant bits.  */
    99    {
   100      int cnt1, cnt2;
   101      mp_bitcnt_t bits1, bits2;
   102  
   103      count_leading_zeros (cnt1, PTR(NUM(op1))[num1_size - 1]);
   104      count_leading_zeros (cnt2, d2h);
   105      bits1 = (mp_bitcnt_t) tmp1_size * GMP_NUMB_BITS - cnt1 - cnt2 + 2 * GMP_NAIL_BITS;
   106  
   107      count_leading_zeros (cnt1, PTR(num_op2)[num2_size - 1]);
   108      count_leading_zeros (cnt2, d1h);
   109      bits2 = (mp_bitcnt_t) tmp2_size * GMP_NUMB_BITS - cnt1 - cnt2 + 2 * GMP_NAIL_BITS;
   110  
   111      if (bits1 > bits2 + 1)
   112        return num1_sign;
   113      if (bits2 + op2_is_int > bits1 + 1)
   114        return -num1_sign;
   115    }
   116  
   117    /* 3. Finally, cross multiply and compare.  */
   118  
   119    TMP_MARK;
   120    if (op2_is_int)
   121      {
   122        tmp2_ptr = TMP_ALLOC_LIMBS (tmp2_size);
   123        tmp1_ptr = PTR(NUM(op1));
   124        --tmp1_size;
   125      }
   126    else
   127      {
   128    TMP_ALLOC_LIMBS_2 (tmp1_ptr,tmp1_size, tmp2_ptr,tmp2_size);
   129  
   130    if (num1_size >= den2_size)
   131      tmp1_size -= 0 == mpn_mul (tmp1_ptr,
   132  			       PTR(NUM(op1)), num1_size,
   133  			       PTR(den_op2), den2_size);
   134    else
   135      tmp1_size -= 0 == mpn_mul (tmp1_ptr,
   136  			       PTR(den_op2), den2_size,
   137  			       PTR(NUM(op1)), num1_size);
   138      }
   139  
   140     if (num2_size >= den1_size)
   141       tmp2_size -= 0 == mpn_mul (tmp2_ptr,
   142  				PTR(num_op2), num2_size,
   143  				PTR(DEN(op1)), den1_size);
   144     else
   145       tmp2_size -= 0 == mpn_mul (tmp2_ptr,
   146  				PTR(DEN(op1)), den1_size,
   147  				PTR(num_op2), num2_size);
   148  
   149  
   150    cc = tmp1_size - tmp2_size != 0
   151      ? tmp1_size - tmp2_size : mpn_cmp (tmp1_ptr, tmp2_ptr, tmp1_size);
   152    TMP_FREE;
   153    return num1_sign < 0 ? -cc : cc;
   154  }
   155  
   156  int
   157  mpq_cmp (mpq_srcptr op1, mpq_srcptr op2)
   158  {
   159    return mpq_cmp_numden (op1, NUM(op2), DEN(op2));
   160  }
   161  
   162  int
   163  mpq_cmp_z (mpq_srcptr op1, mpz_srcptr op2)
   164  {
   165    const static mp_limb_t one = 1;
   166    const static mpz_t den = MPZ_ROINIT_N ((mp_limb_t *) &one, 1);
   167  
   168    return mpq_cmp_numden (op1, op2, den);
   169  }