version 1.1.1.1, 2000/01/10 15:35:27 |
version 1.1.1.2, 2000/09/09 14:12:50 |
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/* mpz_divexact -- finds quotient when known that quot * den == num && den != 0. |
/* mpz_divexact -- finds quotient when known that quot * den == num && den != 0. |
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Copyright (C) 1991, 1993, 1994, 1995 Free Software Foundation, Inc. |
Copyright (C) 1991, 1993, 1994, 1995, 1996, 1997, 1998, 2000 Free Software |
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Foundation, Inc. |
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This file is part of the GNU MP Library. |
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 |
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 |
it under the terms of the GNU Lesser General Public License as published by |
the Free Software Foundation; either version 2 of the License, or (at your |
the Free Software Foundation; either version 2.1 of the License, or (at your |
option) any later version. |
option) any later version. |
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The GNU MP Library is distributed in the hope that it will be useful, but |
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 |
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public |
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
License for more details. |
License for more details. |
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You should have received a copy of the GNU Library General Public License |
You should have received a copy of the GNU Lesser General Public License |
along with the GNU MP Library; see the file COPYING.LIB. If not, write to |
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, |
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
MA 02111-1307, USA. */ |
MA 02111-1307, USA. */ |
Line 27 MA 02111-1307, USA. */ |
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Line 28 MA 02111-1307, USA. */ |
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de Matema'tica at Universidade Federal do Rio Grande do Sul (UFRGS). |
de Matema'tica at Universidade Federal do Rio Grande do Sul (UFRGS). |
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References: |
References: |
T. Jebelean, An algorithm for exact division, Journal of Symbolic |
T. Jebelean, An algorithm for exact division, Journal of Symbolic |
Computation, v. 15, 1993, pp. 169-180. */ |
Computation, v. 15, 1993, pp. 169-180. */ |
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#include "gmp.h" |
#include "gmp.h" |
#include "gmp-impl.h" |
#include "gmp-impl.h" |
Line 46 mpz_divexact (quot, num, den) |
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Line 47 mpz_divexact (quot, num, den) |
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{ |
{ |
mp_ptr qp, tp; |
mp_ptr qp, tp; |
mp_size_t qsize, tsize; |
mp_size_t qsize, tsize; |
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mp_srcptr np, dp; |
mp_srcptr np = num->_mp_d; |
mp_size_t nsize, dsize; |
mp_srcptr dp = den->_mp_d; |
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mp_size_t nsize = ABS (num->_mp_size); |
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mp_size_t dsize = ABS (den->_mp_size); |
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TMP_DECL (marker); |
TMP_DECL (marker); |
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/* Generate divide-by-zero error if dsize == 0. */ |
nsize = ABS (num->_mp_size); |
if (dsize == 0) |
dsize = ABS (den->_mp_size); |
{ |
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quot->_mp_size = 1 / dsize; |
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return; |
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} |
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qsize = nsize - dsize + 1; |
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if (quot->_mp_alloc < qsize) |
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_mpz_realloc (quot, qsize); |
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np = num->_mp_d; |
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dp = den->_mp_d; |
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qp = quot->_mp_d; |
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if (nsize == 0) |
if (nsize == 0) |
{ |
{ |
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if (dsize == 0) |
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DIVIDE_BY_ZERO; |
quot->_mp_size = 0; |
quot->_mp_size = 0; |
return; |
return; |
} |
} |
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qsize = nsize - dsize + 1; |
if (dsize <= 1) |
if (quot->_mp_alloc < qsize) |
{ |
_mpz_realloc (quot, qsize); |
if (dsize == 1) |
qp = quot->_mp_d; |
{ |
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mpn_divmod_1 (qp, np, nsize, dp[0]); |
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qsize -= qp[qsize - 1] == 0; |
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quot->_mp_size = (num->_mp_size ^ den->_mp_size) >= 0 ? qsize : -qsize; |
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return; |
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} |
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/* Generate divide-by-zero error since dsize == 0. */ |
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DIVIDE_BY_ZERO; |
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} |
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TMP_MARK (marker); |
TMP_MARK (marker); |
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/* QUOT <-- NUM/2^r, T <-- DEN/2^r where = r number of twos in DEN. */ |
/* QUOT <-- NUM/2^r, T <-- DEN/2^r where = r number of twos in DEN. */ |
while (dp[0] == 0) |
while (dp[0] == 0) |
np += 1, nsize -= 1, dp += 1, dsize -= 1; |
np += 1, nsize -= 1, dp += 1, dsize -= 1; |
tsize = MIN (qsize, dsize); |
tsize = MIN (qsize, dsize); |
if (dp[0] & 1) |
if ((dp[0] & 1) != 0) |
{ |
{ |
if (qp != dp) |
if (quot == den) /* QUOT and DEN overlap. */ |
MPN_COPY (qp, np, qsize); |
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if (qp == dp) /* QUOT and DEN overlap. */ |
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{ |
{ |
tp = (mp_ptr) TMP_ALLOC (sizeof (mp_limb_t) * tsize); |
tp = (mp_ptr) TMP_ALLOC (tsize * BYTES_PER_MP_LIMB); |
MPN_COPY (tp, dp, tsize); |
MPN_COPY (tp, dp, tsize); |
} |
} |
else |
else |
tp = (mp_ptr) dp; |
tp = (mp_ptr) dp; |
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if (qp != np) |
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MPN_COPY_INCR (qp, np, qsize); |
} |
} |
else |
else |
{ |
{ |
unsigned long int r; |
unsigned int r; |
tp = (mp_ptr) TMP_ALLOC (sizeof (mp_limb_t) * tsize); |
tp = (mp_ptr) TMP_ALLOC (tsize * BYTES_PER_MP_LIMB); |
count_trailing_zeros (r, dp[0]); |
count_trailing_zeros (r, dp[0]); |
mpn_rshift (tp, dp, tsize, r); |
mpn_rshift (tp, dp, tsize, r); |
if (dsize > tsize) |
if (dsize > tsize) |
tp[tsize-1] |= dp[tsize] << (BITS_PER_MP_LIMB - r); |
tp[tsize - 1] |= dp[tsize] << (BITS_PER_MP_LIMB - r); |
mpn_rshift (qp, np, qsize, r); |
mpn_rshift (qp, np, qsize, r); |
if (nsize > qsize) |
if (nsize > qsize) |
qp[qsize-1] |= np[qsize] << (BITS_PER_MP_LIMB - r); |
qp[qsize - 1] |= np[qsize] << (BITS_PER_MP_LIMB - r); |
} |
} |
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/* Now QUOT <-- QUOT/T. */ |
/* Now QUOT <-- QUOT/T. */ |
mpn_bdivmod (qp, qp, qsize, tp, tsize, qsize * BITS_PER_MP_LIMB); |
mpn_bdivmod (qp, qp, qsize, tp, tsize, qsize * BITS_PER_MP_LIMB); |
MPN_NORMALIZE (qp, qsize); |
MPN_NORMALIZE (qp, qsize); |
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quot->_mp_size = (num->_mp_size < 0) == (den->_mp_size < 0) ? qsize : -qsize; |
quot->_mp_size = (num->_mp_size ^ den->_mp_size) >= 0 ? qsize : -qsize; |
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TMP_FREE (marker); |
TMP_FREE (marker); |
} |
} |