134 lines
3.6 KiB
C
134 lines
3.6 KiB
C
/* mpz_tdiv_q -- divide two integers and produce a quotient.
|
|
|
|
Copyright (C) 1991, 1993, 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"
|
|
|
|
void
|
|
#if __STDC__
|
|
mpz_tdiv_q (mpz_ptr quot, mpz_srcptr num, mpz_srcptr den)
|
|
#else
|
|
mpz_tdiv_q (quot, num, den)
|
|
mpz_ptr quot;
|
|
mpz_srcptr num;
|
|
mpz_srcptr den;
|
|
#endif
|
|
{
|
|
mp_srcptr np, dp;
|
|
mp_ptr qp, rp;
|
|
mp_size_t nsize = num->_mp_size;
|
|
mp_size_t dsize = den->_mp_size;
|
|
mp_size_t qsize, rsize;
|
|
mp_size_t sign_quotient = nsize ^ dsize;
|
|
unsigned normalization_steps;
|
|
mp_limb_t q_limb;
|
|
TMP_DECL (marker);
|
|
|
|
nsize = ABS (nsize);
|
|
dsize = ABS (dsize);
|
|
|
|
/* Ensure space is enough for quotient. */
|
|
|
|
qsize = nsize - dsize + 1; /* qsize cannot be bigger than this. */
|
|
if (qsize <= 0)
|
|
{
|
|
quot->_mp_size = 0;
|
|
return;
|
|
}
|
|
|
|
if (quot->_mp_alloc < qsize)
|
|
_mpz_realloc (quot, qsize);
|
|
|
|
qp = quot->_mp_d;
|
|
np = num->_mp_d;
|
|
dp = den->_mp_d;
|
|
|
|
/* Optimize division by a single-limb divisor. */
|
|
if (dsize == 1)
|
|
{
|
|
mpn_divmod_1 (qp, np, nsize, dp[0]);
|
|
qsize -= qp[qsize - 1] == 0;
|
|
quot->_mp_size = sign_quotient >= 0 ? qsize : -qsize;
|
|
return;
|
|
}
|
|
|
|
TMP_MARK (marker);
|
|
|
|
rp = (mp_ptr) TMP_ALLOC ((nsize + 1) * BYTES_PER_MP_LIMB);
|
|
|
|
count_leading_zeros (normalization_steps, dp[dsize - 1]);
|
|
|
|
/* Normalize the denominator, i.e. make its most significant bit set by
|
|
shifting it NORMALIZATION_STEPS bits to the left. Also shift the
|
|
numerator the same number of steps (to keep the quotient the same!). */
|
|
if (normalization_steps != 0)
|
|
{
|
|
mp_ptr tp;
|
|
mp_limb_t nlimb;
|
|
|
|
/* Shift up the denominator setting the most significant bit of
|
|
the most significant word. Use temporary storage not to clobber
|
|
the original contents of the denominator. */
|
|
tp = (mp_ptr) TMP_ALLOC (dsize * BYTES_PER_MP_LIMB);
|
|
mpn_lshift (tp, dp, dsize, normalization_steps);
|
|
dp = tp;
|
|
|
|
/* Shift up the numerator, possibly introducing a new most
|
|
significant word. Move the shifted numerator in the remainder
|
|
meanwhile. */
|
|
nlimb = mpn_lshift (rp, np, nsize, normalization_steps);
|
|
if (nlimb != 0)
|
|
{
|
|
rp[nsize] = nlimb;
|
|
rsize = nsize + 1;
|
|
}
|
|
else
|
|
rsize = nsize;
|
|
}
|
|
else
|
|
{
|
|
/* The denominator is already normalized, as required. Copy it to
|
|
temporary space if it overlaps with the quotient. */
|
|
if (dp == qp)
|
|
{
|
|
dp = (mp_ptr) TMP_ALLOC (dsize * BYTES_PER_MP_LIMB);
|
|
MPN_COPY ((mp_ptr) dp, qp, dsize);
|
|
}
|
|
|
|
/* Move the numerator to the remainder. */
|
|
MPN_COPY (rp, np, nsize);
|
|
rsize = nsize;
|
|
}
|
|
|
|
q_limb = mpn_divmod (qp, rp, rsize, dp, dsize);
|
|
|
|
qsize = rsize - dsize;
|
|
if (q_limb)
|
|
{
|
|
qp[qsize] = q_limb;
|
|
qsize += 1;
|
|
}
|
|
|
|
quot->_mp_size = sign_quotient >= 0 ? qsize : -qsize;
|
|
TMP_FREE (marker);
|
|
}
|