1 /* mpq_cmp(u,v) -- Compare U, V. Return postive, zero, or negative
2 based on if U > V, U == V, or U < V.
4 Copyright (C) 1991, 1994, 1996 Free Software Foundation, Inc.
6 This file is part of the GNU MP Library.
8 The GNU MP Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Library General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or (at your
11 option) any later version.
13 The GNU MP Library is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
16 License for more details.
18 You should have received a copy of the GNU Library General Public License
19 along with the GNU MP Library; see the file COPYING.LIB. If not, write to
20 the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
21 MA 02111-1307, USA. */
29 mpq_cmp (const MP_RAT *op1, const MP_RAT *op2)
36 mp_size_t num1_size = op1->_mp_num._mp_size;
37 mp_size_t den1_size = op1->_mp_den._mp_size;
38 mp_size_t num2_size = op2->_mp_num._mp_size;
39 mp_size_t den2_size = op2->_mp_den._mp_size;
40 mp_size_t tmp1_size, tmp2_size;
41 mp_ptr tmp1_ptr, tmp2_ptr;
50 if ((num1_size ^ num2_size) < 0) /* I.e. are the signs different? */
53 num1_sign = num1_size;
54 num1_size = ABS (num1_size);
55 num2_size = ABS (num2_size);
57 tmp1_size = num1_size + den2_size;
58 tmp2_size = num2_size + den1_size;
60 /* 1. Check to see if we can tell which operand is larger by just looking at
61 the number of limbs. */
63 /* NUM1 x DEN2 is either TMP1_SIZE limbs or TMP1_SIZE-1 limbs.
64 Same for NUM1 x DEN1 with respect to TMP2_SIZE. */
65 if (tmp1_size > tmp2_size + 1)
66 /* NUM1 x DEN2 is surely larger in magnitude than NUM2 x DEN1. */
68 if (tmp2_size > tmp1_size + 1)
69 /* NUM1 x DEN2 is surely smaller in magnitude than NUM2 x DEN1. */
72 /* 2. Same, but compare the number of significant bits. */
75 unsigned long int bits1, bits2;
77 count_leading_zeros (cnt1, op1->_mp_num._mp_d[num1_size - 1]);
78 count_leading_zeros (cnt2, op2->_mp_den._mp_d[den2_size - 1]);
79 bits1 = tmp1_size * BITS_PER_MP_LIMB - cnt1 - cnt2;
81 count_leading_zeros (cnt1, op2->_mp_num._mp_d[num2_size - 1]);
82 count_leading_zeros (cnt2, op1->_mp_den._mp_d[den1_size - 1]);
83 bits2 = tmp2_size * BITS_PER_MP_LIMB - cnt1 - cnt2;
85 if (bits1 > bits2 + 1)
87 if (bits2 > bits1 + 1)
91 /* 3. Finally, cross multiply and compare. */
94 tmp1_ptr = (mp_ptr) TMP_ALLOC (tmp1_size * BYTES_PER_MP_LIMB);
95 tmp2_ptr = (mp_ptr) TMP_ALLOC (tmp2_size * BYTES_PER_MP_LIMB);
97 if (num1_size >= den2_size)
98 tmp1_size -= 0 == mpn_mul (tmp1_ptr,
99 op1->_mp_num._mp_d, num1_size,
100 op2->_mp_den._mp_d, den2_size);
102 tmp1_size -= 0 == mpn_mul (tmp1_ptr,
103 op2->_mp_den._mp_d, den2_size,
104 op1->_mp_num._mp_d, num1_size);
106 if (num2_size >= den1_size)
107 tmp2_size -= 0 == mpn_mul (tmp2_ptr,
108 op2->_mp_num._mp_d, num2_size,
109 op1->_mp_den._mp_d, den1_size);
111 tmp2_size -= 0 == mpn_mul (tmp2_ptr,
112 op1->_mp_den._mp_d, den1_size,
113 op2->_mp_num._mp_d, num2_size);
116 cc = tmp1_size - tmp2_size != 0
117 ? tmp1_size - tmp2_size : mpn_cmp (tmp1_ptr, tmp2_ptr, tmp1_size);
119 return num1_sign < 0 ? -cc : cc;