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/* 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);
}
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