aa9bc17601
BMakefiles and other bits will follow. Requested by: Andrey Chernov Made world by: Chuck Robey
134 lines
3.6 KiB
C
134 lines
3.6 KiB
C
/* mpz_tdiv_q -- divide two integers and produce a quotient.
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Copyright (C) 1991, 1993, 1994, 1996 Free Software Foundation, Inc.
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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
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it under the terms of the GNU Library General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
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License for more details.
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You should have received a copy of the GNU Library General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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#include "longlong.h"
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void
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#if __STDC__
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mpz_tdiv_q (mpz_ptr quot, mpz_srcptr num, mpz_srcptr den)
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#else
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mpz_tdiv_q (quot, num, den)
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mpz_ptr quot;
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mpz_srcptr num;
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mpz_srcptr den;
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#endif
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{
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mp_srcptr np, dp;
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mp_ptr qp, rp;
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mp_size_t nsize = num->_mp_size;
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mp_size_t dsize = den->_mp_size;
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mp_size_t qsize, rsize;
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mp_size_t sign_quotient = nsize ^ dsize;
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unsigned normalization_steps;
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mp_limb_t q_limb;
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TMP_DECL (marker);
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nsize = ABS (nsize);
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dsize = ABS (dsize);
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/* Ensure space is enough for quotient. */
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qsize = nsize - dsize + 1; /* qsize cannot be bigger than this. */
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if (qsize <= 0)
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{
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quot->_mp_size = 0;
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return;
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}
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if (quot->_mp_alloc < qsize)
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_mpz_realloc (quot, qsize);
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qp = quot->_mp_d;
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np = num->_mp_d;
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dp = den->_mp_d;
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/* Optimize division by a single-limb divisor. */
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if (dsize == 1)
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{
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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 = sign_quotient >= 0 ? qsize : -qsize;
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return;
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}
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TMP_MARK (marker);
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rp = (mp_ptr) TMP_ALLOC ((nsize + 1) * BYTES_PER_MP_LIMB);
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count_leading_zeros (normalization_steps, dp[dsize - 1]);
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/* Normalize the denominator, i.e. make its most significant bit set by
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shifting it NORMALIZATION_STEPS bits to the left. Also shift the
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numerator the same number of steps (to keep the quotient the same!). */
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if (normalization_steps != 0)
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{
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mp_ptr tp;
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mp_limb_t nlimb;
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/* Shift up the denominator setting the most significant bit of
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the most significant word. Use temporary storage not to clobber
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the original contents of the denominator. */
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tp = (mp_ptr) TMP_ALLOC (dsize * BYTES_PER_MP_LIMB);
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mpn_lshift (tp, dp, dsize, normalization_steps);
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dp = tp;
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/* Shift up the numerator, possibly introducing a new most
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significant word. Move the shifted numerator in the remainder
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meanwhile. */
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nlimb = mpn_lshift (rp, np, nsize, normalization_steps);
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if (nlimb != 0)
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{
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rp[nsize] = nlimb;
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rsize = nsize + 1;
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}
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else
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rsize = nsize;
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}
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else
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{
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/* The denominator is already normalized, as required. Copy it to
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temporary space if it overlaps with the quotient. */
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if (dp == qp)
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{
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dp = (mp_ptr) TMP_ALLOC (dsize * BYTES_PER_MP_LIMB);
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MPN_COPY ((mp_ptr) dp, qp, dsize);
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}
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/* Move the numerator to the remainder. */
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MPN_COPY (rp, np, nsize);
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rsize = nsize;
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}
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q_limb = mpn_divmod (qp, rp, rsize, dp, dsize);
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qsize = rsize - dsize;
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if (q_limb)
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{
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qp[qsize] = q_limb;
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qsize += 1;
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}
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quot->_mp_size = sign_quotient >= 0 ? qsize : -qsize;
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TMP_FREE (marker);
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}
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