118 lines
3.7 KiB
C
118 lines
3.7 KiB
C
/* mpq_cmp(u,v) -- Compare U, V. Return positive, zero, or negative
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based on if U > V, U == V, or U < V.
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Copyright 1991, 1994, 1996, 2001, 2002, 2005 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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#include "longlong.h"
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int
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mpq_cmp (const MP_RAT *op1, const MP_RAT *op2)
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{
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mp_size_t num1_size = op1->_mp_num._mp_size;
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mp_size_t den1_size = op1->_mp_den._mp_size;
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mp_size_t num2_size = op2->_mp_num._mp_size;
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mp_size_t den2_size = op2->_mp_den._mp_size;
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mp_size_t tmp1_size, tmp2_size;
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mp_ptr tmp1_ptr, tmp2_ptr;
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mp_size_t num1_sign;
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int cc;
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TMP_DECL;
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/* need canonical signs to get right result */
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ASSERT (den1_size > 0);
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ASSERT (den2_size > 0);
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if (num1_size == 0)
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return -num2_size;
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if (num2_size == 0)
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return num1_size;
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if ((num1_size ^ num2_size) < 0) /* I.e. are the signs different? */
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return num1_size;
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num1_sign = num1_size;
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num1_size = ABS (num1_size);
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num2_size = ABS (num2_size);
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tmp1_size = num1_size + den2_size;
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tmp2_size = num2_size + den1_size;
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/* 1. Check to see if we can tell which operand is larger by just looking at
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the number of limbs. */
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/* NUM1 x DEN2 is either TMP1_SIZE limbs or TMP1_SIZE-1 limbs.
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Same for NUM1 x DEN1 with respect to TMP2_SIZE. */
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if (tmp1_size > tmp2_size + 1)
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/* NUM1 x DEN2 is surely larger in magnitude than NUM2 x DEN1. */
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return num1_sign;
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if (tmp2_size > tmp1_size + 1)
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/* NUM1 x DEN2 is surely smaller in magnitude than NUM2 x DEN1. */
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return -num1_sign;
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/* 2. Same, but compare the number of significant bits. */
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{
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int cnt1, cnt2;
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unsigned long int bits1, bits2;
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count_leading_zeros (cnt1, op1->_mp_num._mp_d[num1_size - 1]);
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count_leading_zeros (cnt2, op2->_mp_den._mp_d[den2_size - 1]);
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bits1 = tmp1_size * GMP_NUMB_BITS - cnt1 - cnt2 + 2 * GMP_NAIL_BITS;
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count_leading_zeros (cnt1, op2->_mp_num._mp_d[num2_size - 1]);
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count_leading_zeros (cnt2, op1->_mp_den._mp_d[den1_size - 1]);
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bits2 = tmp2_size * GMP_NUMB_BITS - cnt1 - cnt2 + 2 * GMP_NAIL_BITS;
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if (bits1 > bits2 + 1)
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return num1_sign;
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if (bits2 > bits1 + 1)
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return -num1_sign;
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}
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/* 3. Finally, cross multiply and compare. */
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TMP_MARK;
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TMP_ALLOC_LIMBS_2 (tmp1_ptr,tmp1_size, tmp2_ptr,tmp2_size);
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if (num1_size >= den2_size)
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tmp1_size -= 0 == mpn_mul (tmp1_ptr,
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op1->_mp_num._mp_d, num1_size,
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op2->_mp_den._mp_d, den2_size);
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else
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tmp1_size -= 0 == mpn_mul (tmp1_ptr,
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op2->_mp_den._mp_d, den2_size,
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op1->_mp_num._mp_d, num1_size);
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if (num2_size >= den1_size)
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tmp2_size -= 0 == mpn_mul (tmp2_ptr,
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op2->_mp_num._mp_d, num2_size,
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op1->_mp_den._mp_d, den1_size);
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else
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tmp2_size -= 0 == mpn_mul (tmp2_ptr,
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op1->_mp_den._mp_d, den1_size,
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op2->_mp_num._mp_d, num2_size);
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cc = tmp1_size - tmp2_size != 0
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? tmp1_size - tmp2_size : mpn_cmp (tmp1_ptr, tmp2_ptr, tmp1_size);
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TMP_FREE;
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return num1_sign < 0 ? -cc : cc;
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}
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