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Annotation of OpenXM_contrib/gmp/mpq/cmp.c, Revision 1.1.1.3

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:
1.1.1.3 ! ohara       4: Copyright 1991, 1994, 1996, 2001, 2002 Free Software Foundation, Inc.
1.1       maekawa     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
1.1.1.2   maekawa     9: it under the terms of the GNU Lesser General Public License as published by
                     10: the Free Software Foundation; either version 2.1 of the License, or (at your
1.1       maekawa    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
1.1.1.2   maekawa    15: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
1.1       maekawa    16: License for more details.
                     17:
1.1.1.2   maekawa    18: You should have received a copy of the GNU Lesser General Public License
1.1       maekawa    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: mpq_cmp (const MP_RAT *op1, const MP_RAT *op2)
                     29: {
                     30:   mp_size_t num1_size = op1->_mp_num._mp_size;
                     31:   mp_size_t den1_size = op1->_mp_den._mp_size;
                     32:   mp_size_t num2_size = op2->_mp_num._mp_size;
                     33:   mp_size_t den2_size = op2->_mp_den._mp_size;
                     34:   mp_size_t tmp1_size, tmp2_size;
                     35:   mp_ptr tmp1_ptr, tmp2_ptr;
                     36:   mp_size_t num1_sign;
                     37:   int cc;
                     38:   TMP_DECL (marker);
                     39:
1.1.1.3 ! ohara      40:   /* need canonical signs to get right result */
        !            41:   ASSERT (den1_size > 0);
        !            42:   ASSERT (den2_size > 0);
        !            43:
1.1       maekawa    44:   if (num1_size == 0)
                     45:     return -num2_size;
                     46:   if (num2_size == 0)
                     47:     return num1_size;
                     48:   if ((num1_size ^ num2_size) < 0) /* I.e. are the signs different? */
                     49:     return num1_size;
                     50:
                     51:   num1_sign = num1_size;
                     52:   num1_size = ABS (num1_size);
                     53:   num2_size = ABS (num2_size);
                     54:
                     55:   tmp1_size = num1_size + den2_size;
                     56:   tmp2_size = num2_size + den1_size;
                     57:
                     58:   /* 1. Check to see if we can tell which operand is larger by just looking at
                     59:      the number of limbs.  */
                     60:
                     61:   /* NUM1 x DEN2 is either TMP1_SIZE limbs or TMP1_SIZE-1 limbs.
                     62:      Same for NUM1 x DEN1 with respect to TMP2_SIZE.  */
                     63:   if (tmp1_size > tmp2_size + 1)
                     64:     /* NUM1 x DEN2 is surely larger in magnitude than NUM2 x DEN1.  */
                     65:     return num1_sign;
                     66:   if (tmp2_size > tmp1_size + 1)
                     67:     /* NUM1 x DEN2 is surely smaller in magnitude than NUM2 x DEN1.  */
                     68:     return -num1_sign;
                     69:
                     70:   /* 2. Same, but compare the number of significant bits.  */
                     71:   {
                     72:     int cnt1, cnt2;
                     73:     unsigned long int bits1, bits2;
                     74:
                     75:     count_leading_zeros (cnt1, op1->_mp_num._mp_d[num1_size - 1]);
                     76:     count_leading_zeros (cnt2, op2->_mp_den._mp_d[den2_size - 1]);
1.1.1.3 ! ohara      77:     bits1 = tmp1_size * GMP_NUMB_BITS - cnt1 - cnt2 + 2 * GMP_NAIL_BITS;
1.1       maekawa    78:
                     79:     count_leading_zeros (cnt1, op2->_mp_num._mp_d[num2_size - 1]);
                     80:     count_leading_zeros (cnt2, op1->_mp_den._mp_d[den1_size - 1]);
1.1.1.3 ! ohara      81:     bits2 = tmp2_size * GMP_NUMB_BITS - cnt1 - cnt2 + 2 * GMP_NAIL_BITS;
1.1       maekawa    82:
                     83:     if (bits1 > bits2 + 1)
                     84:       return num1_sign;
                     85:     if (bits2 > bits1 + 1)
                     86:       return -num1_sign;
                     87:   }
                     88:
                     89:   /* 3. Finally, cross multiply and compare.  */
                     90:
                     91:   TMP_MARK (marker);
1.1.1.3 ! ohara      92:   TMP_ALLOC_LIMBS_2 (tmp1_ptr,tmp1_size, tmp2_ptr,tmp2_size);
1.1       maekawa    93:
                     94:   if (num1_size >= den2_size)
                     95:     tmp1_size -= 0 == mpn_mul (tmp1_ptr,
                     96:                               op1->_mp_num._mp_d, num1_size,
                     97:                               op2->_mp_den._mp_d, den2_size);
                     98:   else
                     99:     tmp1_size -= 0 == mpn_mul (tmp1_ptr,
                    100:                               op2->_mp_den._mp_d, den2_size,
                    101:                               op1->_mp_num._mp_d, num1_size);
                    102:
                    103:    if (num2_size >= den1_size)
                    104:      tmp2_size -= 0 == mpn_mul (tmp2_ptr,
                    105:                                op2->_mp_num._mp_d, num2_size,
                    106:                                op1->_mp_den._mp_d, den1_size);
                    107:    else
                    108:      tmp2_size -= 0 == mpn_mul (tmp2_ptr,
                    109:                                op1->_mp_den._mp_d, den1_size,
                    110:                                op2->_mp_num._mp_d, num2_size);
                    111:
                    112:
                    113:   cc = tmp1_size - tmp2_size != 0
                    114:     ? tmp1_size - tmp2_size : mpn_cmp (tmp1_ptr, tmp2_ptr, tmp1_size);
                    115:   TMP_FREE (marker);
                    116:   return num1_sign < 0 ? -cc : cc;
                    117: }