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Diffstat (limited to 'gnu/lib/libgmp/mpq/cmp.c')
| -rw-r--r-- | gnu/lib/libgmp/mpq/cmp.c | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/gnu/lib/libgmp/mpq/cmp.c b/gnu/lib/libgmp/mpq/cmp.c new file mode 100644 index 00000000000..fc530e39540 --- /dev/null +++ b/gnu/lib/libgmp/mpq/cmp.c @@ -0,0 +1,120 @@ +/* mpq_cmp(u,v) -- Compare U, V. Return postive, zero, or negative + based on if U > V, U == V, or U < V. + +Copyright (C) 1991, 1994, 1996 Free Software Foundation, Inc. + +This file is part of the GNU MP Library. + +The GNU MP Library is free software; you can redistribute it and/or modify +it under the terms of the GNU Library General Public License as published by +the Free Software Foundation; either version 2 of the License, or (at your +option) any later version. + +The GNU MP Library is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public +License for more details. + +You should have received a copy of the GNU Library General Public License +along with the GNU MP Library; see the file COPYING.LIB. If not, write to +the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, +MA 02111-1307, USA. */ + +#include "gmp.h" +#include "gmp-impl.h" +#include "longlong.h" + +int +#if __STDC__ +mpq_cmp (const MP_RAT *op1, const MP_RAT *op2) +#else +mpq_cmp (op1, op2) + const MP_RAT *op1; + const MP_RAT *op2; +#endif +{ + mp_size_t num1_size = op1->_mp_num._mp_size; + mp_size_t den1_size = op1->_mp_den._mp_size; + mp_size_t num2_size = op2->_mp_num._mp_size; + mp_size_t den2_size = op2->_mp_den._mp_size; + mp_size_t tmp1_size, tmp2_size; + mp_ptr tmp1_ptr, tmp2_ptr; + mp_size_t num1_sign; + int cc; + TMP_DECL (marker); + + if (num1_size == 0) + return -num2_size; + if (num2_size == 0) + return num1_size; + if ((num1_size ^ num2_size) < 0) /* I.e. are the signs different? */ + return num1_size; + + num1_sign = num1_size; + num1_size = ABS (num1_size); + num2_size = ABS (num2_size); + + tmp1_size = num1_size + den2_size; + tmp2_size = num2_size + den1_size; + + /* 1. Check to see if we can tell which operand is larger by just looking at + the number of limbs. */ + + /* NUM1 x DEN2 is either TMP1_SIZE limbs or TMP1_SIZE-1 limbs. + Same for NUM1 x DEN1 with respect to TMP2_SIZE. */ + if (tmp1_size > tmp2_size + 1) + /* NUM1 x DEN2 is surely larger in magnitude than NUM2 x DEN1. */ + return num1_sign; + if (tmp2_size > tmp1_size + 1) + /* NUM1 x DEN2 is surely smaller in magnitude than NUM2 x DEN1. */ + return -num1_sign; + + /* 2. Same, but compare the number of significant bits. */ + { + int cnt1, cnt2; + unsigned long int bits1, bits2; + + count_leading_zeros (cnt1, op1->_mp_num._mp_d[num1_size - 1]); + count_leading_zeros (cnt2, op2->_mp_den._mp_d[den2_size - 1]); + bits1 = tmp1_size * BITS_PER_MP_LIMB - cnt1 - cnt2; + + count_leading_zeros (cnt1, op2->_mp_num._mp_d[num2_size - 1]); + count_leading_zeros (cnt2, op1->_mp_den._mp_d[den1_size - 1]); + bits2 = tmp2_size * BITS_PER_MP_LIMB - cnt1 - cnt2; + + if (bits1 > bits2 + 1) + return num1_sign; + if (bits2 > bits1 + 1) + return -num1_sign; + } + + /* 3. Finally, cross multiply and compare. */ + + TMP_MARK (marker); + tmp1_ptr = (mp_ptr) TMP_ALLOC (tmp1_size * BYTES_PER_MP_LIMB); + tmp2_ptr = (mp_ptr) TMP_ALLOC (tmp2_size * BYTES_PER_MP_LIMB); + + if (num1_size >= den2_size) + tmp1_size -= 0 == mpn_mul (tmp1_ptr, + op1->_mp_num._mp_d, num1_size, + op2->_mp_den._mp_d, den2_size); + else + tmp1_size -= 0 == mpn_mul (tmp1_ptr, + op2->_mp_den._mp_d, den2_size, + op1->_mp_num._mp_d, num1_size); + + if (num2_size >= den1_size) + tmp2_size -= 0 == mpn_mul (tmp2_ptr, + op2->_mp_num._mp_d, num2_size, + op1->_mp_den._mp_d, den1_size); + else + tmp2_size -= 0 == mpn_mul (tmp2_ptr, + op1->_mp_den._mp_d, den1_size, + op2->_mp_num._mp_d, num2_size); + + + cc = tmp1_size - tmp2_size != 0 + ? tmp1_size - tmp2_size : mpn_cmp (tmp1_ptr, tmp2_ptr, tmp1_size); + TMP_FREE (marker); + return num1_sign < 0 ? -cc : cc; +} |