132 lines
3.0 KiB
C
132 lines
3.0 KiB
C
/* mpn_submul_1 -- multiply the N long limb vector pointed to by UP by VL,
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subtract the N least significant limbs of the product from the limb
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vector pointed to by RP. Return the most significant limb of the
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product, adjusted for carry-out from the subtraction.
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Copyright 1992, 1993, 1994, 1996, 2000, 2002, 2004 Free Software Foundation,
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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 Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 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 Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser 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., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, 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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#if GMP_NAIL_BITS == 0
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mp_limb_t
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mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t vl)
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{
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mp_limb_t ul, cl, hpl, lpl, rl;
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ASSERT (n >= 1);
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ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n));
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cl = 0;
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do
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{
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ul = *up++;
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umul_ppmm (hpl, lpl, ul, vl);
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lpl += cl;
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cl = (lpl < cl) + hpl;
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rl = *rp;
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lpl = rl - lpl;
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cl += lpl > rl;
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*rp++ = lpl;
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}
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while (--n != 0);
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return cl;
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}
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#endif
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#if GMP_NAIL_BITS == 1
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mp_limb_t
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mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t vl)
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{
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mp_limb_t shifted_vl, ul, rl, lpl, hpl, prev_hpl, cl, xl, c1, c2, c3;
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ASSERT (n >= 1);
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ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n));
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ASSERT_MPN (rp, n);
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ASSERT_MPN (up, n);
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ASSERT_LIMB (vl);
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shifted_vl = vl << GMP_NAIL_BITS;
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cl = 0;
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prev_hpl = 0;
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do
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{
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ul = *up++;
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rl = *rp;
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umul_ppmm (hpl, lpl, ul, shifted_vl);
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lpl >>= GMP_NAIL_BITS;
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SUBC_LIMB (c1, xl, rl, prev_hpl);
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SUBC_LIMB (c2, xl, xl, lpl);
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SUBC_LIMB (c3, xl, xl, cl);
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cl = c1 + c2 + c3;
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*rp++ = xl;
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prev_hpl = hpl;
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}
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while (--n != 0);
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return prev_hpl + cl;
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}
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#endif
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#if GMP_NAIL_BITS >= 2
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mp_limb_t
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mpn_submul_1 (mp_ptr rp, mp_srcptr up, mp_size_t n, mp_limb_t vl)
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{
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mp_limb_t shifted_vl, ul, rl, lpl, hpl, prev_hpl, xw, cl, xl;
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ASSERT (n >= 1);
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ASSERT (MPN_SAME_OR_SEPARATE_P (rp, up, n));
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ASSERT_MPN (rp, n);
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ASSERT_MPN (up, n);
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ASSERT_LIMB (vl);
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shifted_vl = vl << GMP_NAIL_BITS;
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cl = 0;
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prev_hpl = 0;
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do
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{
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ul = *up++;
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rl = *rp;
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umul_ppmm (hpl, lpl, ul, shifted_vl);
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lpl >>= GMP_NAIL_BITS;
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xw = rl - (prev_hpl + lpl) + cl;
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cl = (mp_limb_signed_t) xw >> GMP_NUMB_BITS; /* FIXME: non-portable */
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xl = xw & GMP_NUMB_MASK;
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*rp++ = xl;
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prev_hpl = hpl;
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}
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while (--n != 0);
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return prev_hpl - cl;
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}
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#endif
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