Return to cmp.c CVS log

Up to [local] / OpenXM_contrib / gmp / mpq

Annotation of OpenXM_contrib/gmp/mpq/cmp.c, Revision 1.1

1.1     ! maekawa     1: /* mpq_cmp(u,v) -- Compare U, V.  Return postive, zero, or negative
        !             2:    based on if U > V, U == V, or U < V.
        !             3:
        !             4: Copyright (C) 1991, 1994, 1996 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 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.
        !            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 Library General Public
        !            16: License for more details.
        !            17:
        !            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. */
        !            22:
        !            23: #include "gmp.h"
        !            24: #include "gmp-impl.h"
        !            25: #include "longlong.h"
        !            26:
        !            27: int
        !            28: #if __STDC__
        !            29: mpq_cmp (const MP_RAT *op1, const MP_RAT *op2)
        !            30: #else
        !            31: mpq_cmp (op1, op2)
        !            32:      const MP_RAT *op1;
        !            33:      const MP_RAT *op2;
        !            34: #endif
        !            35: {
        !            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;
        !            42:   mp_size_t num1_sign;
        !            43:   int cc;
        !            44:   TMP_DECL (marker);
        !            45:
        !            46:   if (num1_size == 0)
        !            47:     return -num2_size;
        !            48:   if (num2_size == 0)
        !            49:     return num1_size;
        !            50:   if ((num1_size ^ num2_size) < 0) /* I.e. are the signs different? */
        !            51:     return num1_size;
        !            52:
        !            53:   num1_sign = num1_size;
        !            54:   num1_size = ABS (num1_size);
        !            55:   num2_size = ABS (num2_size);
        !            56:
        !            57:   tmp1_size = num1_size + den2_size;
        !            58:   tmp2_size = num2_size + den1_size;
        !            59:
        !            60:   /* 1. Check to see if we can tell which operand is larger by just looking at
        !            61:      the number of limbs.  */
        !            62:
        !            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.  */
        !            67:     return num1_sign;
        !            68:   if (tmp2_size > tmp1_size + 1)
        !            69:     /* NUM1 x DEN2 is surely smaller in magnitude than NUM2 x DEN1.  */
        !            70:     return -num1_sign;
        !            71:
        !            72:   /* 2. Same, but compare the number of significant bits.  */
        !            73:   {
        !            74:     int cnt1, cnt2;
        !            75:     unsigned long int bits1, bits2;
        !            76:
        !            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;
        !            80:
        !            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;
        !            84:
        !            85:     if (bits1 > bits2 + 1)
        !            86:       return num1_sign;
        !            87:     if (bits2 > bits1 + 1)
        !            88:       return -num1_sign;
        !            89:   }
        !            90:
        !            91:   /* 3. Finally, cross multiply and compare.  */
        !            92:
        !            93:   TMP_MARK (marker);
        !            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);
        !            96:
        !            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);
        !           101:   else
        !           102:     tmp1_size -= 0 == mpn_mul (tmp1_ptr,
        !           103:                               op2->_mp_den._mp_d, den2_size,
        !           104:                               op1->_mp_num._mp_d, num1_size);
        !           105:
        !           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);
        !           110:    else
        !           111:      tmp2_size -= 0 == mpn_mul (tmp2_ptr,
        !           112:                                op1->_mp_den._mp_d, den1_size,
        !           113:                                op2->_mp_num._mp_d, num2_size);
        !           114:
        !           115:
        !           116:   cc = tmp1_size - tmp2_size != 0
        !           117:     ? tmp1_size - tmp2_size : mpn_cmp (tmp1_ptr, tmp2_ptr, tmp1_size);
        !           118:   TMP_FREE (marker);
        !           119:   return num1_sign < 0 ? -cc : cc;
        !           120: }