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 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 the GNU Lesser General Public License as published by 10 the Free Software Foundation; either version 3 of the License, or (at your 11 option) any later version. 12 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 Lesser General Public 16 License for more details. 17 18 You should have received a copy of the GNU Lesser General Public License 19 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ 20 21 #include "gmp.h" 22 #include "gmp-impl.h" 23 #include "longlong.h" 24 25 int 26 mpq_cmp (const MP_RAT *op1, const MP_RAT *op2) 27 { 28 mp_size_t num1_size = op1->_mp_num._mp_size; 29 mp_size_t den1_size = op1->_mp_den._mp_size; 30 mp_size_t num2_size = op2->_mp_num._mp_size; 31 mp_size_t den2_size = op2->_mp_den._mp_size; 32 mp_size_t tmp1_size, tmp2_size; 33 mp_ptr tmp1_ptr, tmp2_ptr; 34 mp_size_t num1_sign; 35 int cc; 36 TMP_DECL; 37 38 /* need canonical signs to get right result */ 39 ASSERT (den1_size > 0); 40 ASSERT (den2_size > 0); 41 42 if (num1_size == 0) 43 return -num2_size; 44 if (num2_size == 0) 45 return num1_size; 46 if ((num1_size ^ num2_size) < 0) /* I.e. are the signs different? */ 47 return num1_size; 48 49 num1_sign = num1_size; 50 num1_size = ABS (num1_size); 51 num2_size = ABS (num2_size); 52 53 tmp1_size = num1_size + den2_size; 54 tmp2_size = num2_size + den1_size; 55 56 /* 1. Check to see if we can tell which operand is larger by just looking at 57 the number of limbs. */ 58 59 /* NUM1 x DEN2 is either TMP1_SIZE limbs or TMP1_SIZE-1 limbs. 60 Same for NUM1 x DEN1 with respect to TMP2_SIZE. */ 61 if (tmp1_size > tmp2_size + 1) 62 /* NUM1 x DEN2 is surely larger in magnitude than NUM2 x DEN1. */ 63 return num1_sign; 64 if (tmp2_size > tmp1_size + 1) 65 /* NUM1 x DEN2 is surely smaller in magnitude than NUM2 x DEN1. */ 66 return -num1_sign; 67 68 /* 2. Same, but compare the number of significant bits. */ 69 { 70 int cnt1, cnt2; 71 unsigned long int bits1, bits2; 72 73 count_leading_zeros (cnt1, op1->_mp_num._mp_d[num1_size - 1]); 74 count_leading_zeros (cnt2, op2->_mp_den._mp_d[den2_size - 1]); 75 bits1 = tmp1_size * GMP_NUMB_BITS - cnt1 - cnt2 + 2 * GMP_NAIL_BITS; 76 77 count_leading_zeros (cnt1, op2->_mp_num._mp_d[num2_size - 1]); 78 count_leading_zeros (cnt2, op1->_mp_den._mp_d[den1_size - 1]); 79 bits2 = tmp2_size * GMP_NUMB_BITS - cnt1 - cnt2 + 2 * GMP_NAIL_BITS; 80 81 if (bits1 > bits2 + 1) 82 return num1_sign; 83 if (bits2 > bits1 + 1) 84 return -num1_sign; 85 } 86 87 /* 3. Finally, cross multiply and compare. */ 88 89 TMP_MARK; 90 TMP_ALLOC_LIMBS_2 (tmp1_ptr,tmp1_size, tmp2_ptr,tmp2_size); 91 92 if (num1_size >= den2_size) 93 tmp1_size -= 0 == mpn_mul (tmp1_ptr, 94 op1->_mp_num._mp_d, num1_size, 95 op2->_mp_den._mp_d, den2_size); 96 else 97 tmp1_size -= 0 == mpn_mul (tmp1_ptr, 98 op2->_mp_den._mp_d, den2_size, 99 op1->_mp_num._mp_d, num1_size); 100 101 if (num2_size >= den1_size) 102 tmp2_size -= 0 == mpn_mul (tmp2_ptr, 103 op2->_mp_num._mp_d, num2_size, 104 op1->_mp_den._mp_d, den1_size); 105 else 106 tmp2_size -= 0 == mpn_mul (tmp2_ptr, 107 op1->_mp_den._mp_d, den1_size, 108 op2->_mp_num._mp_d, num2_size); 109 110 111 cc = tmp1_size - tmp2_size != 0 112 ? tmp1_size - tmp2_size : mpn_cmp (tmp1_ptr, tmp2_ptr, tmp1_size); 113 TMP_FREE; 114 return num1_sign < 0 ? -cc : cc; 115 } 116